LUMINA: A prospective trial omitting radiotherapy (RT) following breast conserving surgery (BCS) in T₁N₀ luminal A breast cancer (BC).

Abstract

LBA501 Background: Adjuvant breast RT is usually prescribed following BCS to reduce the risk of local recurrence (LR). However, this treatment is inconvenient, costly, and associated with acute and late toxicity. Traditional clinical pathological factors (CPFs) alone are limited in their ability to identify women with a low enough risk of LR to omit RT. Molecular defined intrinsic subtypes of BC provide additional prognostic information with luminal A having the lowest risk of recurrence. A retrospective analysis of a previous trial suggested that women >60 years with luminal A grade 1-2 T1N0 BC treated by BCS and endocrine therapy alone had a low rate of LR ( JCO 2015; 33:2035). The utility of identifying luminal A subtype combined with CPFs has not been prospectively evaluated for its ability to guide RT decision-making. Methods: A prospective multicenter cohort study was performed. Eligibility criteria were: women ≥ 55 years; having undergone BCS for grade 1-2 T1N0 BC; ≥ 1mm margins of excision; luminal A subtype (defined as: ER ≥ 1%, PR>20%, HER2 negative and Ki67 ≤ 13.25%); and treated with adjuvant endocrine therapy. ER, PR and HER2 were performed locally as per ASCO guidelines. Patients meeting clinical eligibility with ER ≥ 1%, PR>20%, HER2 negative BC were registered and had Ki67 immunohistochemistry performed centrally in one of three Canadian laboratories using International Ki67 Working Group methods. Proficiency testing between laboratories was performed yearly. Patients with Ki67 ≤ 13.25% were enrolled in the trial and were assigned to not receive RT. The primary outcome was LR defined as time from enrollment to any invasive or non-invasive cancer in the ipsilateral breast. Assuming a 5-year LR rate of 3.5%, 500 patients were required to show that the upper bound of a two sided 90% (one-sided 95%) confidence interval (CI) was <5%. Patients were followed every six months for the first two years and then yearly. The probability of LR was estimated using the cumulative incidence function with death as a competing risk. Secondary outcomes were contralateral BC; relapse free survival (RFS) based on any recurrence; disease free survival (DFS) based on any recurrence, second cancer or death; and overall survival (OS). Results: From August 2013 to July 2017, 501 of 727 registered patients from 26 centers had a Ki67 ≤ 13.25% and were enrolled. Median follow-up was 5 years. Median age was 67 and 442 (88%) patients were <75 years. Median tumor size was 1.1 cm. The 5-year rate of LR satisfied our pre-specified boundary (see Table). Conclusions: Women ≥ 55 years with grade 1-2 T1N0 luminal A BC following BCS treated with endocrine therapy alone had very low rates of LR at 5 years and are candidates for omission of RT. Clinical trial information: NCT01791829. [Table: see text]

Accelerated Partial Breast Irradiation

“…Recently, the LUMINA trial, a prospective multicenter cohort study, also showed that endocrine therapy alone achieved very low rates of local recurrence without postoperative irradiation (5-year rate, 2.3%) in patients 55 years or older affected by a luminal-like, grade 1-2, pT1 N0 breast cancer. 27 However, it should be strongly considered that adjuvant endocrine therapy might significantly compromise patients' HRQoL. 28 Moreover, compliance and adherence to planned endocrine therapy are well known to decrease over time.…”

ASCO 2022 Breast Cancer Updates

“…LUMINA trial is a phase III study of 500 patients 55 years or older with invasive ductal cancer stage I HR-positive, luminal A, defined as ER≥1%, PR >20 %, HER2-negative and Ki 67 ≤13.25%, grade 1 or 2, omitting radiation therapy after lumpectomy, sentinel node biopsy and endocrine therapy. The study is reporting a 5 year follow up a with a 2.3% local recurrence rate, concluding that patients with low-risk breast cancer can forgo radiation therapy after breast conserving surgery and endocrine therapy (47). Can we now omit radiation therapy?…”

American Society of Clinical Oncology 2022 Annual Meeting Highlights for Radiation Oncologists

“…Abstract Chmura 2 Oral 1007 Breast LUMINA: A prospective trial omitting radiotherapy (RT) following breast conserving surgery (BCS) in T 1 N 0 luminal A breast cancer (BC). Abstract 363918 Whelan 5 Oral LBA501 CNS Phase II randomized study comparing proton craniospinal irradiation with photon involved-field radiotherapy for patients with solid tumor leptomeningeal metastasis Yang 10 Oral 2000 CNS A controlled comparison of cerebral volume loss after brain irradiation with proton versus photon radiotherapy. Abstract 376740 Gardner 12 Poster discussion 2017 GI Single agent PD-1 blockade as curative-intent treatment in mismatch repair deficient locally advanced rectal cancer.…”