As reported in The Lancet Oncology by Williams et al, long-term follow-up of the phase III Scottish Breast Conservation Trial indicated that postoperative radiotherapy was associated with a significantly reduced risk of ipsilateral recurrence vs no radiotherapy in patients undergoing breast-conserving surgery for breast cancer, although the difference in risk after 10 years of follow-up was not significant.
Study Details
In the Scottish multicenter trial, 585 eligible patients aged < 70 years with early breast cancer (tumors ≤ 4 cm; T1 or T2 and N0 or N1) were randomly assigned between April 1985 and October 1991 to receive (n = 291) or not receive (n = 294) postoperative radiotherapy. Radiotherapy consisted of local or locoregional radiotherapy at 50 Gy in 20 to 25 fractions. Estrogen receptor (ER)-rich patients (≥ 20 fmol/mg protein) received 20 mg of oral tamoxifen daily for 5 years. ER-poor patients (< 20 fmol/mg protein) received chemotherapy consisting of cyclophosphamide at 600 mg/m², methotrexate at 50 mg/m², and fluorouracil at 600 mg/m² every 21 days in eight courses.
Our findings suggest that patients whose biology predicts a late relapse a decade or more after breast-conserving surgery for early breast cancer might gain little from adjuvant radiotherapy.— Williams et al
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Key Findings
Median follow-up was 17.5 years (interquartile range = 8.4–27.9 years).
Overall, ipsilateral recurrence was observed in 46 (16%) of 291 patients in the radiotherapy group vs 107 (36%) of 294 patients in the no radiotherapy group (hazard ratio [HR] = 0.39, 95% confidence interval [CI] = 0.28–0.55, P < .0001). The difference in risk during the first 10 years after treatment was statistically significant (HR = 0.24, 95% CI = 0.15–0.38, P < .0001); subsequent risk was similar in both groups (HR = 0.98, 95% CI = 0.54–1.79, P = .95).
Median overall survival was 18.7 years (95% CI = 16.5-21.5 years) in the no radiotherapy group vs 19.2 years (95% CI = 16.9–21.3 years) in the radiotherapy group (HR = 1.08, 95% CI = 0.89–1.30, P = .43). Overall survival at 30 years was 27.5% (95% CI = 22.0%–32.9%) in the no radiotherapy group vs 23.7% (95% CI = 18.3%–29.0%) in the radiotherapy group. Among 221 patients who died in the no radiotherapy group and 222 who died in the radiotherapy group, 46% vs 37% died from breast cancer (P = .054) and 11% vs 20% died from other cancers (P = .012), respectively.
The investigators concluded, “Our findings suggest that patients whose biology predicts a late relapse a decade or more after breast-conserving surgery for early breast cancer might gain little from adjuvant radiotherapy.”
Linda J. Williams, PhD, of the Edinburgh Clinical Trials Unit, Usher Institute, University of Edinburgh, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by Breast Cancer Institute (part of Edinburgh and Lothian Health Foundation) and PFS Genomics (now part of Exact Sciences). For full disclosures of the study authors, visit thelancet.com.
