{"entity":{"id":"prime-ii","kind":"trial","name":"PRIME II","aka":[],"tldr":"PRIME II confirmed in a larger and more recent population that omitting radiotherapy in older women with low-risk hormone-sensitive breast cancer raises local recurrence modestly without affecting survival.","summary":"PRIME II randomised 1,326 women aged 65 or older with hormone receptor-positive, node-negative breast cancers up to 3 cm, treated by breast-conserving surgery and endocrine therapy, to radiotherapy or none. Ten-year local recurrence was 9.5 percent without radiotherapy and 0.9 percent with it; distant recurrence, breast cancer-specific and overall survival did not differ (Kunkler and colleagues, Lancet Oncology 2015 and New England Journal of Medicine 2023).","status":"positive","asOf":"2026-09-16","links":[{"label":"ISRCTN95889329","url":"https://www.isrctn.com/ISRCTN95889329"},{"label":"NEJM 2023","url":"https://doi.org/10.1056/NEJMoa2207586"}],"tags":["radiation-wave2"],"related":[],"cancers":["breast-hr-positive","breast-cancer"],"sections":[],"technologies":["imrt-igrt","active-surveillance"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["radiotherapy-omission-early-breast-cancer"],"trials":["calgb-9343","lumina"],"people":[],"bottlenecks":[],"keyPapers":["paper-kunkler-n-engl-j-med"],"journals":[],"dependsOn":[],"notes":[],"phase":"3","setting":"Women aged 65 or over with low-risk hormone receptor-positive breast cancer after breast-conserving surgery: endocrine therapy with or without whole-breast radiotherapy","sponsor":"University of Edinburgh","result":"10-year local recurrence 9.5% (no radiotherapy) vs 0.9% (radiotherapy); no difference in survival.","yearReported":2015,"enrolled":1326,"enrolledBasis":"registry","outcomes":[{"endpoint":"Ipsilateral breast tumour recurrence at 10 years","primary":true,"unit":"%","arms":[{"name":"Endocrine therapy alone","n":668,"value":9.5},{"name":"Endocrine therapy plus radiotherapy","n":658,"value":0.9}]}]},"route":"/trials/prime-ii/","neighbours":{"cancer":[{"id":"breast-cancer","kind":"cancer","name":"Breast cancer (all types)","route":"/cancers/breast-cancer/"},{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"}],"technology":[{"id":"active-surveillance","kind":"technology","name":"Active surveillance","route":"/technologies/active-surveillance/"},{"id":"imrt-igrt","kind":"technology","name":"IMRT / IGRT (modern external beam)","route":"/technologies/imrt-igrt/"}],"term":[{"id":"radiotherapy-omission-early-breast-cancer","kind":"term","name":"Leaving radiotherapy out","route":"/terms/radiotherapy-omission-early-breast-cancer/"}],"trial":[{"id":"calgb-9343","kind":"trial","name":"CALGB 9343","route":"/trials/calgb-9343/"},{"id":"lumina","kind":"trial","name":"LUMINA","route":"/trials/lumina/"}],"paper":[{"id":"paper-kunkler-n-engl-j-med","kind":"paper","name":"Breast-Conserving Surgery with or without Irradiation in Early Breast Cancer","route":"/key-papers/paper-kunkler-n-engl-j-med/"}]}}