Table 1

Available items in the International Consortium for Pooled Studies on Subsequent Malignancies after Childhood and Adolescent Cancer database

Data information	Requested items for consortium database	Comments
Childhood cancer diagnosis characteristics	Year and month of birth Year and month of childhood cancer diagnosis ICD-O-3 morphology code, behaviour code and topography code Laterality (left/right/bilateral/not applicable/unknown)	SJLIFE: no ICD-O-3 coding, but detailed description of tumour type in words FCCSS: no ICD-O-3 coding, but coded according to ICCC-3 DHL: no ICD-O-3 coding available Consortium database: childhood cancer type recoded into ICCC-3 groups
General treatment exposure	All: yes/no/unknown Radiotherapy Chemotherapy Surgery	CCSS: any treatment for the primary tumour up to five years following primary diagnosis SJLIFE/NWTSG/DCCSS LATER/ FCCSS/SCCSS/DHL: all known treatments for primary tumours and/or recurrences
Radiotherapy body region exposure	All: yes/no/unknown and delivered dose to body compartment: Head/neck Chest Abdomen Pelvis Extremities Total body irradiation	CCSS/SJILFE: body region dosimetry; maximum prescribed target dose to the specific body region; taken as the sum of dose from all overlapping fields in a region. At least 10% of body region in the field to be scored as direct exposure ‘yes’, with the exception for the brain, where at least 50% of the brain segment had to be in the field. Exposure to head/neck was coded as exposure to either any of the brain segments, other head, or neck NWTSG/DCCSS LATER/SCCSS/DHL: in case of multiple radiotherapy treatments to a specific body region, the dose of the fields was summed if the fields were overlapping. If the fields were not overlapping, the dose to the field with the highest dose was assigned (highest dose to smallest field principle) FCCSS: exposure to body compartments was based on dosimetry information of organs at risk in that specific body compartment
Chest fields	Data providers were requested to provide data on each field to the chest area as part of childhood cancer treatment according to the categories listed below, or to provide the coding of fields that they used in their own database. In case the data providers provided their own coding of fields (CCSS/SJLIFE/DCCSS LATER/DHL), these were then recoded by the Máxima team, in close collaboration with the data providers, into the categories listed below. Total body irradiation Whole lung Mantle field Mediastinal Axilla (both/left/right/unknown) Spine* Chest without axilla (left/right/other/unknown) Also, the delivered dose of each field was recorded. Comments: The ‘Chest without axilla’ category includes a mixed group of patients with treated radiotherapy fields that do not fit any of the other specific categories. Therefore, we have no information on the part of the breast that may or may not have been within the treatment beam. For analyses, if patients had multiple fields to the same region, the dose was summed, with two exceptions: If a left axilla field and a right axilla field were irradiated, the maximum dose of the two respective fields was chosen. If two or more fields were chest without axilla, we chose the maximum dose of the respective fields for that person, because it was unclear whether there was any overlap of radiation exposure from those respective fields.
Chemotherapy	Drug name Cumulative dose	NWTSG: cumulative dose not available
Follow-up information	Year and month of last information on subsequent malignant neoplasms Vital status (alive/deceased/unknown) Year and month of last known vital status information Invasive breast cancer diagnosis (yes/no/unknown) In situ breast cancer diagnosis (yes/no/unknown) Diagnosis of other subsequent malignancies (yes/no/unknown)	FCCSS: information on subsequent malignancies other than breast cancers is only available for breast cancer cases
Invasive and in situ breast cancer	For each (in situ) breast cancer case: ICD-O-3 morphology code ICD-O-3 behaviour code ICD-O-3 topography code Laterality (left/right/bilateral/unknown) Year and month of diagnosis Tumour receptor status: Oestrogen, human epidermal growth factor receptor 2 and progesterone status (negative/positive/unknown)	DCCSS LATER: no information on tumour receptor status
Other subsequent malignant neoplasms	ICD-O-3 morphology code, behaviour code and topography code Year and month of diagnosis Chest radiotherapy treatment for subsequent malignant neoplasm (yes/no/unknown) Anthracycline treatment for subsequent malignant neoplasm (yes/no/unknown)	CCSS/DCCSS LATER/DHL: information on chest radiotherapy and anthracycline treatment given for any other subsequent neoplasms is not available, but information on the other variables is FCCSS: information on subsequent malignancies other than breast cancers is only available for breast cancer cases
Reproductive factors	Age at menarche Menopausal status (premenopausal/postmenopausal/unknown) and age at menopause Parity and age first childbirth	SJLIFE: menopausal status and age at menopause available for a few patients, but largely incomplete NWTSG: age at menarche, menopausal status and age at menopause are not available SCCSS: data available for a subset of patients from questionnaires
Hormonal use	Oral contraceptive use and duration of oral contraceptive use for contraception Hormone replacement therapy and duration of hormone replacement therapy use	SJLIFE/NWTSG: not available SCCSS: data available for a subset of patients from questionnaires
Other	Family history of breast cancer in first-degree relatives and in second-degree relatives	SCCSS: not available NWTSG/DHL: only available for first-degree relatives
	Race	DCCSS LATER/FCCSS/SCCSS/DHL: not available
	Treatment protocol name	DCCSS LATER/FCCSS/DHL: not available
	Ovarian transplantation before pelvic field irradiation	SJLIFE/NWTSG/DCCSS LATER/SCCSS/DHL: not available
	Breast dosimetry performed, absorbed breast dose, ovarian dosimetry performed, absorbed ovarian dose	NWTSG/DCCSS LATER/SCCSS/DHL: not available

*Spine irradiation fields not involving a thoracic part of the spine were not considered chest radiotherapy.
CCSC, Childhood Cancer Survivor Study; DCCSS LATER, Dutch Long-term Effects After Childhood Cancer Study; DHL, Dutch Hodgkin Late Effects cohort; FCCSS, French Childhood Cancer Survivor Study; ICCC, International Classification of Childhood Cancer, Third Edition; ICD-O-3, International Classification of Diseases for Oncology, Third Edition; NWTSG, US National Wilms Tumour Study group; SCCSS, Swiss Childhood Cancer Survivor Study; SJLIFE, St. Jude Lifetime Cohort Study.