Extended Follow Up and Data Registry Substudy in Australia and New Zealand for the participants of ANZ 1501 POSNOC (POsitive Sentinel NOde Clearance) study.

Australian and New Zealand participants in the POSNOC study ((ISRCTN54765244, NCT02401685) will be invited to participate in this extended follow up and data registry substudy. Data collection in this project will be obtained by: 1. One additional follow up in 2026 (when the final patient recruited to POSNOC has reached 5 years of follow up). Data will be collected from the participant's medical record to determine date of most recent contact, presence of recurrences or new breast cancer events, nature of any such events, vital status. Data linkage will be used where a patient cannot be contacted; and 2. Subsequent follow up by data linkage. The data will be requested from the respective national and jurisdictional data registries for Australia and New Zealand such as the Australian Institute of Health and Welfare (AIHW) and New Zealand’s Breast Cancer Foundation National Register (BCFNR). Data will be cleaned and securely stored on servers within the Breast Cancer Trials, Trials Department, Newcastle, NSW Australia. Relevant data relating POSNOC will be forwarded to UK sponsors and incorporated into the POSNOC clinical trial dataset stored at Nottingham Clinical Trial Unit, Nottingham, UK. Identifying patient data signified with ‘*’ will not leave Australian territory. + Unique ID/POSNOC participant identifier + Surname (including any previous names)* + Given name/s* + Sex + Date of birth* + State (for Australian participants)* + Vital status at last follow up + Address*. Applications using this information will be made to the Australian Institute of Health and Welfare (AIHW) and New Zealand’s Breast Cancer Foundation National Register (BCFNR) to link the following data to those participants: + Vital status/Current patient status + Date of death + Cause of death + ICD10AM code (AUS) for new cancers (i.e. International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, Australian Modification). + Date of new cancer diagnosis/Date of definitive diagnosis of NEW primary + Cancer details (type, site, size, topography and morphology) This follow up and data collection via data linkage will collect further health status information to avoid causing unnecessary distress to the family, as it will avert inappropriate contact if the woman has died following discharge from hospital-based follow up. It will reduce losses to follow up and will also enable longer term follow up data (greater than 5 years) to be reported. The objectives of the POSNOC Extended Follow Up and Data Registry substudy are the same as those of the main POSNOC study. The objective of this substudy is to increase the power of the study to address the questions. It is expected that the addition of complete mortality and cancer incidence data from the Australian and New Zealand participants in addition to that collected in the UK will increase the power of the POSNOC study to determine whether adjuvant therapy alone is no worse than adjuvant therapy plus axillary treatment. Main study: Protocol RD-5103-001-13 - A randomized controlled trial of axillary treatment in women with early stage breast cancer who have metastases in one or two sentinel nodes. ISRCTN54765244 NCT02401685