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Abstract
Objective Breast self-examination (BSE) is the most feasible screening tool compared with clinical breast examination and mammography. It is crucial to address the associated factors of practising BSE to develop a targeted BSE promotion programme and improve the BSE quality in Thai women, particularly during the COVID-19 pandemic.
Design and setting We conducted a cross-sectional study in Thailand’s north and northeast region from March 2020 to November 2022.
Participants This study involved 405 women aged 30–70 years old.
Variables and outcomes Demographic information, health status and BSE were collected using a modified questionnaire based on the Champion Health Belief Model. The outcomes were ever-practising BSE, BSE practice within the last 6 months, continuity of BSE and confidence in doing BSE. Logistic regression and decision tree analysis identified the associated factors.
Results 75.55% of participants ever performed BSE. Around 74.18% did BSE within the last 6 months. Diploma graduates (adjusted OR (aOR) 25.48, 95% CI 2.04 to 318.07), 21–40 reproductive years (aOR 4.29, 95% CI 1.22 to 15.08), ever pregnant (aOR 3.31, 95% CI 1.05 to 10.49), not drinking alcohol (aOR 2.1, 95% CI 1.04 to 4.55), not receiving hormone replacement (aOR 5.51, 95% CI 2.04 to 14.89), higher knowledge (aOR 1.29, 95% CI 1.09 to 1.52), attitude (aOR 1.15, 95% CI 1.05 to 1.26) and practice/cues of action towards BSE were associated with ever-practising BSE. Frequent high-fat diet, high awareness of breast cancer, lower knowledge of BSE and lower attitude toward BSE were associated with not practising BSE within 6 months and BSE discontinuation. Only high knowledge of BSE was associated with absolute confidence in BSE (p<0.05).
Conclusion Despite having a higher percentage than other studies in different countries prior to the pandemic, it is still crucial to improve knowledge of BSE to encourage BSE practice, confidence and continuity of BSE in Thai women. Moreover, the BSE campaign should target women with prolonged exposure to oestrogen and sedentary lifestyle.
- Breast tumours
- PREVENTIVE MEDICINE
- Quality in health care
- Health Education
Data availability statement
Data are available upon reasonable request. Data are available at our online repository upon reasonable request. To request access to the underlying research data, please contact Dr Bumi Herman (bumi.h@chula.ac.th).
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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STRENGTHS AND LIMITATIONS OF THIS STUDY
This study was conducted amid the COVID-19 pandemic in Thailand.
A multistage random sampling was implemented in participant recruitment.
This study used the Thai version of Champion Health Belief Model Questionnaire, adjusted for breast self-examination to measure breast cancer awareness.
Instead of ordinal logistic regression, a decision tree was implemented to identify the associated factors of ordinal level of breast self-examination confidence.
As this study was focusing on the region in which breast cancer was more prevalent (north and the northeast), the generalisability of the finding, particularly in urban areas such as greater Bangkok, is limited.
Introduction
Breast cancer is a malignancy from the epithelial layer of the ducts and lobules of the breast glandular tissue. Due to the limited structure of this tissue, breast cancer at an early stage is sometimes unrecognisable until a notable tissue degeneration occurs, which in this stage, further dissemination of cancer cells to adjacent lymph nodes structure is inevitable.1 Breast cancer was estimated in 2020 as the most commonly diagnosed cancer, surpassing lung cancer.2 The WHO stated that 2.26 million women were diagnosed with breast cancer and 685 000 fatalities worldwide.3 In Thailand, the breast cancer incidence rate per year per 100 000 population during a 5-year cohort analysis (2013–2017) was 31, with the mortality rate per year per 100 000 reaching 176.4
Breast cancer is linked to oestrogen exposure, worsened by a sedentary lifestyle and genetic vulnerability. Furthermore, breast cancer occurs in males in smaller percentages. The quality of life of those with breast cancer is deteriorating due to symptoms, intractable pain, mental health disturbance (such as depression) and sexual dysfunction.5 The global burden of breast cancer is noticeable in lower social development index countries, and the related disability-adjusted life years were 17 708 600 in 2017.6
It is imperative to reduce the burden of breast cancer by intensifying the screening and diagnosis of breast cancer. The survival rate among people with early-stage breast cancer who underwent treatment is high. The study in Uruguay reveals that after investing in breast cancer education and screening modalities for 20 years, there was a decrease in the standardised incidence rate from 77.3 cases per 100 000 person-years in 2002 to 71.1 in 2015.7
Radiology examination of breast cancer involves ultrasound and mammography as the first line. The ultrasound contributes to incremental findings of 0.3–7.7 cases per 1000 tests and increases the number of biopsies following the suggestive ultrasound finding to 11.7–106.6 biopsies per 1000 tests,8 but ultrasound is a high-cost examination. Mammography could identify calcification and abnormal breast density. However, this procedure is costly and there is an incremental risk of radiation to the breast.9 Moreover, in low/middle-income countries with less advanced healthcare systems, alternative procedures to mammography are more realistic.10 Hence, the WHO did not recommend this procedure in these countries.11 Biopsy, either through surgical or fine-needle aspiration, is one of the breast cancer diagnoses based on histology and cytological changes. This method has higher sensitivity in the palpable lesion and less sensitivity in the non-palpable lesion,12 although this procedure is costly and time-consuming if it is treated as first-line screening.
The clinical breast examination (CBE) and breast self-examination (BSE) aim to detect any anatomical changes in the breast suggesting malignancy. The difference between these procedures is the one who conducted the examination. The CBE relies on health professionals, whereas the woman could do BSE anytime. An overview indicates the equivalence of the well-performed CBE with the mammography. CBE sensitivity is high among younger age and Asian women. The implementation of CBE could shift the detection of late-stage cancer to early-stage.13 Despite the great benefit of CBE, it seems inaccessible in a low-resource setting, leaving BSE as the most feasible way to screen breast cancer. Furthermore, the COVID-19 pandemic leads to limited hospital visits and an increasing burden on healthcare workers, meaning that screening by health professionals is difficult to access.
As BSE is fundamental, exploring the factors associated with practising it is relevant. Several previous studies’ results were conflicting, and it is challenging to generalise this finding to the Thai context. The theory of Health Belief Model (HBM) is applicable to identify these factors. This consists of perceived severity (related to how severe the breast cancer could affect the individual life), perceived susceptibility (the chance of getting the disease), perceived benefit (benefit from doing the breast screening), perceived barriers (something that hinders the intention to do the breast screening), cues to action (reminder or any event that initiate the breast screening) and self-efficacy.14
Deploying possible factors to HBM could portray a clear relationship between these factors and the practice of BSE. Identifying the risk factor of breast cancer in an individual could predict the perceived severity and susceptibility of a person towards breast cancer which eventually affects the practice of BSE. The risk of breast cancer could be related to health status, lifestyle, the presence of chronic disease and any event that could lead to prolonged oestrogen exposure.15 Demographic factors and knowledge regarding breast cancer may affect the perceived benefit and self-efficacy of doing breast screening. Several factors are also related to the perceived barriers and cues to action, including access to healthcare and health information through breast cancer promotion.
This study aimed to address the factors associated with the practice of BSE, the continuity of doing BSE and the confidence in BSE in the Thai population, particularly during the COVID-19 pandemic. The findings are essential to developing a targeted BSE education programme and improving the existing BSE campaigns in Thailand.
Methodology
Setting and study design
We performed a cross-sectional study in four provinces with the highest number of breast cancer cases in Thailand, including Chiang Rai, Udon Thani, Lamphun and Nakhon Ratchasima (all these provinces covered the north and northeast area of Thailand) from March 2020 to November 2022. The data collection was conducted by the data collector using a questionnaire delivered by interview.
Participants’ eligibility
This study involved women aged 30–70 years recruited using multistage random sampling from the provincial to district levels, as at this age, the prevalence of breast cancer is high.4 Participants should live in the study area for at least 5 years and be fluent in Thai. This study excluded people or migrant workers who had not transferred their rights to medical care in the provinces of domicile for at least 6 months or did not reside in the study area although listed in the local health system.
Variables
There were three groups of predictors in this study. First is the demographic factors correlated with performing cancer screening,16 including age, occupation, income, education, marital status and type of insurance. Second, the health information of the subjects, consisting of body mass index (BMI), age at first menstruation, regularity of menstrual period, menopause status, history of pregnancy, presence of congenital disease, family history of any cancer or breast cancer. Factors associated with breast cancer were collected, including the use of a contraceptive drug for more than 3 months17 and or hormone replacement,18 alcohol drinking19 and smoking.20 Regular exercise was defined as moderately active according to the WHO STEPwise Approach to Non Communicable Disease Risk Factor Surveillance (STEPS) survey.21 This study recorded the frequency of eating a high-fat diet, as breast cancer is associated with this behaviour.22
Measurement tools
This study developed a questionnaire in the Thai language based on the Champion HBM Questionnaire23 adjusted for BSE to measure breast cancer awareness, knowledge, attitude and practice towards BSE. Three experts tested the content validity of this questionnaire using Item-Objective Congruence (IOC). An IOC of at least 0.5 is considered acceptable for the measurement tools.
The domain awareness of breast cancer consists of 21 5-point Likert scale questions ranging from strongly disagree to strongly agree, with a range of values 0–4. The questions were related to the perceived risk of getting breast cancer and the perceived benefit of BSE. The total score of this domain is 84. A higher awareness score indicates a high perceived risk of breast cancer and less benefit from doing BSE. The reliability Cronbach’s alpha for this domain is 0.825. The domain knowledge has 11 questions with three responses (yes, no and do not know). This domain comprises the BSE procedure questions and the importance of the BSE. The total score of this domain is 12, where a higher score indicates higher knowledge of how to do BSE. The reliability Cronbach’s alpha for this domain is 0.790. The attitude domain discusses participants’ reasoning for engaging BSE with 12 questions. The responses were agree, do not know and disagree. The total score of this domain is 24, where a high number represents a better attitude and reflects a higher intention to do BSE. The reliability Cronbach’s alpha for this domain is 0.625. The last domain is practice, with 10 questions in three levels (always, rarely and never). A higher number reflects the higher reception of information on breast cancer (related to cues of action) and BSE and practice of BSE appropriately, with a maximum value of 20. The reliability Cronbach’s alpha for this domain is 0.868. The overall reliability of this questionnaire is 0.816.
Outcomes
This study has four outcomes related to BSE. The first outcome is whether the participants ever conducted BSE. The second outcome is whether the clients did BSE within the last 6 months. The third outcome represents the confidence of the clients in doing the examination. The fourth outcome is whether the participants do BSE continuously or stop doing the BSE. All variables were binary except the confidence level that represents the confidence in doing BSE.
Study size and possible bias
Researchers calculated sample size using a one-sample proportion with the assumptions as follows. The type I error value was 5%. The percentage of people who did the BSE in Thailand was 72%.4 With a margin of error of 0.05, the total sample needed was 310 participants. With an incomplete response set at 5%, the minimum number of respondents for analysis should be at least 326 participants. A questionnaire delivered by interview would reduce the response and recall bias as the participant would understand the meaning of the questions.24 The data collectors underwent training to prevent interviewer bias.
Quantitative variable
We discretised age, income and age at first menstruation as presented in table 1. Asian BMI classification was applied as this classification estimates female-specific cancer better.25 The duration of menstruation in life was calculated as the age of menopause, subtracted by the age of the first menstruation. For participants who were not menopause, this variable was calculated by subtracting the current age from the age of first menstruation. This variable reflects the duration of exposure to endogenous oestrogen throughout life, as this could be related to breast cancer,26 assuming the menstrual cycle is regular.
Participant characteristics
Statistical analysis
Data underwent cleaning, and no imputation method was applied. Descriptive statistics and normality tests revealed the distribution of quantitative data. A bivariate analysis was made between each independent variable and the outcomes, followed by logistic regression to find the associated factors of each outcome and the adjusted OR (aOR). The decision tree was preferred to the ordinal regression for the outcome variable of more than two levels (the variable confidence of doing BSE) as the assumption of ordinal regression was not fulfilled. A Χ2 Automatic Interaction Detection growing method was executed as some predictors have more than two levels. The maximum depth was 10, with the number of minimum cases in the parent node and child node being 100 and 50, respectively. The significance value for splitting and merging the node was 0.05. Additional Sobel tests would demonstrate the possible indirect effect of the predictors and the outcome.
Patient and public involvement
Participants were involved in recruitment through the snowball method within their communities. Participants and the public can disseminate and use research results for the development of future breast cancer promotion policies, particularly those who work as village health volunteers.
Results
A total of 405 participants were involved in this study. However, only 302 participants provided complete responses for all outcomes. Hence, pairwise analysis was conducted with the number of participants for each analysis depicted in table 1. The average age of 405 participants was 46.39±9.82 years old, with 75.55% ever performing the BSE. Around 63.9% of people who never practise BSE prefer CBE. Among 306 participants, around 74.18% did the BSE within 6 months. However, only 29.73% of participants expressed absolute confidence in their BSE. Furthermore, 26.14% of them stopped doing BSE (figure 1). Three main reasons why participants stopped doing BSE were lack of time to do BSE (48.8%), preferring to check with health staff (36.3%) and did not perform BSE correctly (35.0%).
Decision tree of confidence in breast self-examination. Knowledge is the only associated factor of confidence.
From bivariate analysis, age group, marital status and type of insurance were associated with ever-practising BSE, although the type of insurance was the only demographic factor associated with practising BSE within 6 months and continuing to do BSE (online supplemental table 1). Interestingly, a family history of breast cancer was not associated with all outcomes. Awareness, knowledge, attitude and practice of BSE were associated with all outcomes (p<0.001), as shown in table 2.
Supplemental material
Concept of BSE and the outcomes
The logistic regression model in table 3 depicts the significant association of education and engagement to BSE, particularly among diploma graduates compared with people without formal education. People who experienced pregnancy and did not receive hormone replacement therapy (HRT) and did not drink alcohol tend to perform BSE. The increase in the high-fat diet frequency did not show a consistently significant association with never practising BSE. Regarding the duration of menstruation in the lifetime, people in the duration of menstruation within 21–40 years tend to practise BSE compared with those less than 20 years. The increase in knowledge and attitude to BSE score were the significant factors of ever-practising BSE. There was no association between awareness of breast cancer and ever-practising BSE.
Logistic regression model of ever-practising BSE with predictors of p<0.2
Concerning the practice of BSE within 6 months and the continuity of doing BSE, people who eat a high-fat diet once daily (aOR 0.088, 95% CI 0.011 to 0.683) and increase in awareness scores were associated with no practise of BSE within 6 months (aOR 0.941, 95% CI 0.908 to 0.975). The last two factors were also associated with continuity of performing BSE (aOR 0.087, 95% CI 0.011 to 0.724 for eating a high-fat diet once daily and aOR 0.945, 95% CI 0.912 to 0.979 for one score increase of awareness). An increase in knowledge and attitude score was associated with the practise of BSE in the last 6 months and also BSE continuity (online supplemental tables 2 and 3). A decision tree analysis was an alternative to ordinal logistic regression to analyse the confidence in doing BSE. Using the predefined decision tree analysis and entering all possible predictors (from online supplemental table 1), knowledge of BSE was the significant factor of confidence in BSE (p<0.001), where a score of more than 6 indicates a higher percentage of absolute confidence, as depicted in figure 1.
Discussion
During the COVID-19 pandemic, this study revealed a higher percentage of ever doing BSE (75.5%) in Thai women compared with Ethiopia (21–65%),27 Kuwait (21%)28 and Indonesia (44.4%).28 Moreover, this percentage was still consistent with the prevalence of doing BSE within 6 months (74.18%). One of the prominent factors that might support this finding is the BSE national campaign. However, this study addressed a lower percentage of absolute confidence in BSE results (29.73%) and recorded 26.14% of BSE discontinuation. In this study, the participants expressed their reluctance to BSE if they have a high awareness of having breast cancer, as they might not be ready to accept the positive findings such as lump, discolouration and other breast disorders.
The impact of education to ever-practise BSE seems inconsistent across the level. However, there was a significant difference in BSE practice among diploma graduates compared with women without formal education. This finding is similar to a systematic review from Ethiopia stating that women with no formal education were 60% less likely to perform BSE.27 A bivariate analysis of education level and BSE practice also showed a similar finding in Indonesia.28 Researchers looked for any association between the level of education and knowledge of breast cancer and BSE. In additional bivariate analysis (online supplemental table 4), there was no significant association between education and knowledge score (p=0.700). Therefore, it is crucial to focus on increasing the knowledge of breast cancer and BSE without a rigorous adjustment on education level in BSE campaigns or promotion.
In bivariate analysis, the type of insurance seems to affect the BSE practice, although the logistic regression model did not confirm this finding. There was a tendency (although not significant) that people under Universal Health Coverage Scheme were more likely to keep continuing BSE compared with those with private health insurance (OR 1.708, 95% CI 0.656 to 4.444), but the different results were seen in people under Social Security Scheme (SSC) (OR 0.734, 95% CI 0.265 to 2.031) and Civil Servant Medical Benefit Scheme/CSMBS (OR 0.695, 95% CI 0.237 to 2.037) (online supplemental table 5). Health insurance in Thailand is divided into public universal health coverage and private insurance. There is a subtle disparity in cancer coverage among these types of insurance, where private insurance has a narrow cancer coverage. In terms of access to cancer medication, according to National Comprehensive Cancer Network, CSMBS has better access and coverage compared with other types of insurance.29 By nature, people will go for disease screening and further treatment if their insurance covers the recommended screening and standard care. However, it seems contrary to the finding of this study that people with more extensive cancer coverage (CSMBS, SSC) were less likely to continue BSE. It should be noted that we did not record whether the non-performers of BSE underwent more effective screening methods and skipped BSE, which then the association between health insurance and BSE practice to become inconclusive and should be carefully interpreted. Although the findings were insignificant, it is still necessary to include health insurance literacy in the BSE education programme and consider further cancer coverage expansion in the health policy (handling perceived barriers).
Cancer is theoretically associated with the genetic alteration. Family history of non-specific cancer or breast cancer is not relevant to the BSE practice and all outcomes in this study, but conflicting results appeared in Kuwait,30 Indonesia28 and Ethiopia.27 The association of a family history of breast cancer with the practice of BSE was insignificant. Furthermore, this was similar to the study on the women who live on the Mexico–US border.31 An assumption arises that lifestyle and other factors related to hormone exposure play more significant roles in affecting the perceived risk of breast cancer than the history of breast cancer within the family. Again, we could not eliminate the probability of people with a family history of cancer may undergo advanced screening techniques.
There are two group factors related to breast cancer. First is prolonged exposure to oestrogen, and we assumed that people with prolonged exposure to oestrogen would increase their perceived risk and affects BSE practice. Aside from other factors such as the number of completed pregnancies, age at first childbirth and experience of breast feeding, this study identified the age of menstruation, menopause status, regularity of menstruation, duration of having menstruation in a lifetime and taking contraceptive drugs as the variables related to prolonged exposure to oestrogen. The age group, menopause and regularity of menstruation were not associated with the practice of BSE in this research.
A systematic review of 117 epidemiological studies stated that premenopausal women were at a high risk of breast cancer compared with postmenopausal women at identical ages.32 Our study findings showed that people with duration of menstruation (reproductive years) in a lifetime of 21–40 years tend to perform BSE. In this survey, most people in this group belong to the premenopausal stage. This finding is linear with the theory that people in the high-risk group tend to perform health screening.
There is an assumption that the length of menstruation years is linear to the risk of breast cancer. Variations of oestrogen exposure and the interaction with its receptor play pivotal roles in breast cancer occurrence. Women could have external exposure to oestrogen through oral contraceptives and HRT that contain oestrogen derivatives. The oral contraceptive is associated with breast cancer33 and independent of the duration of oral contraceptive use.34 This finding is also similar among people who underwent oestrogen-HRT.35 Regardless of this higher perceived risk, there was no difference in BSE practice among people who used contraceptive drugs, and a similar finding was found in Malaysia.36
Pregnancy is considered a protective factor in breast cancer, particularly for the oestrogen-receptor+ type of breast cancer.37 In this study, people with a history of pregnancy engaged to BSE three times higher than nulliparous. There is no sufficient study to support this finding. Also, in this study, people who underwent HRT were less likely to practise BSE. Hence, this contradicts the theory of perceived risk and engagement in health practice.
This study excluded breastfeeding analysis due to a higher non-response rate. Breast feeding’s impact on breast cancer is dubious. In theory, suppressing oestrogen through prolactin release during breast feeding is assumed to be a protective factor against breast cancer. Nevertheless, the increase of prolactin itself is associated with breast cancer.38 A review disclosed the inconsistency of lactation to breast cancer.39
The Sobel test estimated the indirect effect of factors associated with prolonged oestrogen exposure (duration of menstruation, oral contraception, HRT, pregnancy) and practice of BSE, mediated by the perceived possibility of developing breast cancer (awareness question 4), and did not confirm a theory that people with prolonged oestrogen exposure may affect the BSE practice, mediated by perceived risk (online supplemental table 5). In summary, prolonged oestrogen exposure has proven to affect breast cancer but not consistently affect the perceived risk and, eventually, the BSE practice.
The second group of factors is health behaviour. A study in Brazil revealed that alcohol consumption, sedentary lifestyle and smoking were associated with breast cancer,40 thus, may increase the perceived risk of breast cancer. However, the logistic regression model showed that people who did not drink alcohol tended to perform BSE twice higher than those who drank. Still, there was no difference in practice of BSE concerning the exercise and smoking variable. Considering the continuity of doing BSE, the sedentary lifestyle factors (alcohol drinking and physical inactivity) did not affect the continuity of doing BSE (online supplemental table 3), and this result is similar to the study among future health professionals in Ghana.41 There was an association between high-fat intake and breast cancer, and in our study, people who eat a high-fat diet once daily were less likely to perform BSE continuously (online supplemental table 3). One of the questions in receiving behaviour domain expressed the concern of participants whether they are at risk of developing breast cancer. There was an assumption that the risky behaviour may increase their perceived risk, thus, affecting the decision to perform and continue doing BSE. However, using the Sobel test to assess the indirect effect of risky behaviour on the practice and continuity of BSE (mediated by awareness of developing breast cancer), there were no significant indirect associations (p>0.05). Therefore, it is important to recalibrate their mindset that certain unhealthy lifestyles may possess the risk of developing breast cancer. The development of the BSE programme should emphasise the link between unhealthy lifestyles and breast cancer to reset their perceived risk and engagement in BSE.
This study identified BSE’s awareness, knowledge, attitude and practice using the questionnaire developed for Thai people. The higher awareness score indicates high concern that breast cancer could happen at any time, and BSE is crucial to detect breast cancer. There was no significant association between awareness and ever-practising BSE. However, people with high awareness scores did not perform BSE within 6 months and were less likely to do it continuously (online supplemental tables 2 and 3). It is similar to a study in African countries that awareness is irrelevant to practice.42 Knowledge of BSE was associated with the practice of BSE, doing BSE within 6 months, continuity of doing BSE (online supplemental table 3) and confidence in doing BSE. This finding is similar to the study in Ghana.43 The domain knowledge focused on the procedure of BSE and only asked one question regarding menopause. It is vital to include more knowledge of risk factors in this domain. As the percentage of BSE practice is already higher in this population, it is essential to point out the confidence in doing BSE. The decision tree model confirmed the association in having higher knowledge and absolute confidence in the BSE results. Thus, the BSE education programme should focus on improving BSE knowledge to increase confidence in doing BSE. Attitude toward BSE had a significant association with four outcomes practice of BSE, doing BSE within 6 months and continuity of doing BSE (online supplemental tables 1–3). The practice score of BSE did not associate with doing BSE within 6 months and continuity of doing BSE (online supplemental tables 2 and 3). The content of this domain is not only about whether the participants did the BSE but also related to whether the participant received information about breast cancer and how to do BSE from an external source (proactive in or persuaded by other people), which could explain why the practice score was not associated with other outcomes except ever-practise BSE.
In conclusion, to increase BSE practice, it is essential to focus on improving knowledge, rectifying the awareness and attitude toward BSE, expanding knowledge of specific risk factors for breast cancer and disseminating the information to the target population. Thailand’s healthcare system is strengthened by the village health volunteer, which has proven to be resilient in managing health problems using a community approach. These people live together with their community, allowing them to be more efficient in conducting health promotion and be an example for their community. Hence, improving the knowledge and attitude of BSE could be maximised by empowering these health volunteers.
Limitation
Researchers have noticed that this study did not achieve the minimum sample for the complete response. However, adjusting the sample size with the percentage of BSE practice in this study could justify the sample sufficiency (a minimum of 288). It is fundamental to address the issue that a self-reported questionnaire might provide better privacy rather than be delivered through the interview. However, the face-to-face interview might reduce the recall bias,44 and this study also shortened the recall period (BSE within 6 months) to overcome this issue. Researchers acknowledge that the study did not recruit participants from the central and southern parts of Thailand, which hinders the generalisability of this study. The COVID-19 restriction (travel and social restriction) in this study was the underlying reason why only a small number of participants could be recruited.
Conclusion and recommendation
This study recorded a higher percentage of BSE practice and addressed the most fundamental factors of ever-practising BSE. Higher knowledge of BSE is associated with all outcomes, including ever-practise BSE, doing BSE within 6 months, continuity of doing BSE and confidence in the BSE results. People who engage in a healthy lifestyle tend to practise BSE. Hence, it is necessary to develop BSE campaigns or educational programmes involving the village health volunteers, including healthy lifestyle promotion and recognising various breast cancer risks. At a greater level, expanding coverage for cancer treatment (prevention, screening, treatment and rehabilitation) in the current health insurance scheme may encourage more people to do BSE.
Data availability statement
Data are available upon reasonable request. Data are available at our online repository upon reasonable request. To request access to the underlying research data, please contact Dr Bumi Herman (bumi.h@chula.ac.th).
Ethics statements
Patient consent for publication
Ethics approval
This study involves human participants and was approved by the Research Ethics Review Committee for Research Involving Human Research Participants, Group 1 Chulalongkorn University (COA no. 047/2563). Participants provided written consent before data collection. All data were de-identified to protect the confidentiality of the participants and were used according to the research objectives.
Acknowledgments
Researchers would like to express gratitude to the College of Public Health, Chulalongkorn University Thailand, for the support of the study.
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
Contributors ST is the guarantor and contributed to the conceptualisation of the study as well as providing the clinical review. MC, PW, WS, SS and OZ contributed to the participant recruitment in each region, and conducted investigation and supervision of data collection, ensuring that the research was following the protocol and the variable measurement was accurately performed. BH conducted the initial statistical analysis, provided a clinical review and wrote the manuscript draft, while NH and PV finalised the statistical analysis and final manuscript. Approval was gained from all authors before submission for publication.
Funding Thanyarak Foundation funded the study under the Royal Patronage of Her Royal Highness Princess Maha Chakri Sirindhorn (award/grant no: NA, to author ST) and the Second Century Fund Chulalongkorn University (award/grant no: NA, to author BH).
Disclaimer This funding source had no role in the design of this study and will not have any role during its execution, analyses, interpretation of the data or decision to submit results.
Competing interests None declared.
Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.