Molecular Risk Stratification for Decision-Making Among Patients With Breast Cancer Eligible to Omit Radiation...

Area of Science:

• Oncology
• Radiation Oncology
• Genomics

Background:

• Radiotherapy after breast-conserving surgery (BCS) is standard for early-stage breast cancer.
• Selected patients with favorable characteristics may omit radiotherapy, accepting a small increase in recurrence risk without impacting survival.
• Molecular risk profiling could refine selection for or against radiotherapy omission.

Purpose of the Study:

• To assess if Oncotype DX Recurrence Score (RS) can further stratify radiotherapy omission risk in older patients.
• To identify a higher-risk subgroup unsuitable for omission and an exceedingly-favorable subgroup for omission.

Main Methods:

• Retrospective analysis of patients aged ≥65 undergoing BCS for ER+ early-stage breast cancer.
• Stratification by clinicopathologic features and Oncotype DX RS (≤25 vs >25).
• Evaluation of oncologic outcomes and survival based on radiotherapy receipt.

Main Results:

• The cohort (n=1,587) was predominantly RS ≤25 (92%).
• Local recurrence rates were low and not significantly different between RS ≤25 and RS >25 groups (6-year rate 1.9% vs 0.8%).
• Among radiotherapy-omitted patients (n=350), RS >25 (n=19) did not show a higher local recurrence risk than RS ≤25 (6-year rate 5.6% vs 4.2%).

Conclusions:

• Oncotype DX RS did not significantly refine recurrence risk for radiotherapy decisions in this patient group.
• Patients with RS >25 who omitted radiotherapy did not have a significantly higher risk, suggesting RS may not disqualify them from omission.
• Larger prospective studies are needed to confirm the role of molecular assays in guiding radiotherapy decisions across risk strata.