Objectives Cancer can be diagnosed in the absence of tumour-related symptoms, but little is known about the frequency and circumstances preceding such diagnoses which occur outside participation in screening programmes. We aimed to examine incidentally diagnosed cancer among a cohort of cancer patients diagnosed in England.
Design Cross-sectional study of national primary care audit data on an incident cancer patient population.
Setting We analysed free-text information on the presenting features of cancer patients aged 15 or older included in the English National Audit of Cancer Diagnosis in Primary Care (2009–2010). Patients with screen-detected cancers or prostate cancer were excluded. We examined the odds of incidental cancer diagnosis by patient characteristics and cancer site using logistic regression, and described clinical scenarios leading to incidental diagnosis.
Results Among the studied cancer patient population (n=13 810), 520 (4%) patients were diagnosed incidentally. The odds of incidental cancer diagnosis increased with age (p<0.001), with no difference between men and women after adjustment. Incidental diagnosis was most common among patients with leukaemia (23%), renal (13%) and thyroid cancer (12%), and least common among patients with brain (0.9%), oesophageal (0.5%) and cervical cancer (no cases diagnosed incidentally). Variation in odds of incidental diagnosis by cancer site remained after adjusting for age group and sex.
There was a range of clinical scenarios preceding incidental diagnoses in primary or secondary care. These included the monitoring or management of pre-existing conditions, routine testing before or after elective surgery, and the investigation of unrelated acute or new conditions.
Conclusions One in 25 patients with cancer in our population-based cohort were diagnosed incidentally, through different mechanisms across primary and secondary care settings. The epidemiological, clinical, psychological and economic implications of this phenomenon merit further investigation.
- primary care
- radiology & imaging
- public health
- health services administration & management
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Contributors MMK, GR and GL conceived the study. MMK conducted all statistical analyses with assistance from GL. MMK wrote the first draft of the manuscript, and prepared the tables and figures, supervised by GL. MMK, GR, SMcP and GL contributed to the interpretation of the results, revised the manuscript and approved the final version of the manuscript.
Funding This work was supported by the UK Department of Health as part of the programme of the Policy Research Unit in Cancer Awareness, Screening and Early Diagnosis [grant number no. 106/0001]. The Policy Research Unit in Cancer Awareness, Screening, and Early Diagnosis is a collaboration between researchers from seven institutions (Queen Mary University of London, University College London, King’s College London, London School of Hygiene and Tropical Medicine, Hull York Medical School, Durham University and Peninsula Medical School/University of Exeter). GL is supported by Cancer Research UK Clinician Advanced Scientist Fellowship [grant number: C18081/A18180]. GR is Chair, GL Associate Director and MMK Junior Faculty member of the multi-institutional CanTest Collaborative, which is funded by Cancer Research UK (C8640/A23385).The views expressed are those of the authors and not necessarily those of the Department of Health or Cancer Research UK. The funders of the study had no role in the study design, data analysis, data interpretation or writing of the report. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Ethical approval was not required given the anonymous nature of these data.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement The data used for our analysis can be accessed through the National Cancer Registration and Analysis Service. Enquiries for data access can be made to Public Health England’s Office for Data Release (email@example.com).
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