POSNOC

POSNOC is a pragmatic multicentre non-inferiority trial that randomised 1,900 women with one or two sentinel node macrometastases 1:1 to adjuvant therapy alone or to adjuvant therapy plus axillary treatment, the latter being either axillary node clearance or axillary radiotherapy at the centre's choice. Randomisation was stratified by institution, age, breast-conserving surgery or mastectomy, oestrogen receptor status, number of positive nodes and whether intraoperative one-step nucleic acid amplification was used.

The design detail that makes POSNOC different from Z0011 and SENOMAC is a prohibition: in the adjuvant-therapy-alone arm, axillary and supraclavicular fossa radiotherapy is not allowed. Breast or chest-wall radiotherapy is. So the experimental arm genuinely receives no axillary treatment, which is not true of either predecessor, and the trial includes women having mastectomy and women with microscopic extranodal invasion, neither of whom Z0011 admitted. The United Kingdom Radiotherapy Trials Quality Assurance Group runs an in-built radiotherapy quality assurance programme, so the fields are documented rather than assumed.

The primary endpoint is axillary recurrence within five years, with arm morbidity measured by the Lymphoedema and Breast Cancer Questionnaire and QuickDASH, quality of life by FACT B+4, and a health-economic evaluation. Recruitment opened on 1 August 2014 and closed at the 1,900 target; the ClinicalTrials.gov record gives an estimated primary completion of July 2026 and the trial is listed as active and no longer recruiting. No results have been published, and none are quoted here.