As reported in The Lancet Oncology by de Wild et al, 5-year follow-up from a Dutch prospective registry study (RAPCHEM, BOOG 2010-03) showed low rates of locoregional recurrence with de-escalation of adjuvant radiotherapy according to predefined risk levels in women receiving primary chemotherapy and surgery for cT1-2N1 breast cancer.
Study Details
The 5-year analysis included 838 eligible women, enrolled between January 2011 and January 2015, with cT1-2N1 breast cancer (1–3 suspicious nodes on imaging before primary chemotherapy, of which at ≥ 1 had been pathologically confirmed) who were treated with primary chemotherapy and surgery. Patients were assigned to predefined risk groups for locoregional recurrence: low = ypN0; intermediate = ypN1, one to three positive nodes in the surgical specimen after primary chemotherapy; or high = ypN2-3, four or more positive nodes in the surgical specimen after primary chemotherapy.
Patients in the low-risk group (n = 291) received no chest wall radiotherapy and no regional radiotherapy; those in the intermediate-risk group (n = 370) received only local radiotherapy; and those in the high-risk group (n = 177) received locoregional radiotherapy. Radiotherapy consisted of a biologically equivalent dose of 25 fractions of 2 Gy with or without a boost. It was hypothesized that the 5-year locoregional recurrence rate would be < 4% (upper limit of 95% confidence interval [CI] = 7.8%).
Key Findings
Among all patients, 5-year locoregional recurrence was 2.2% (95% CI = 1.4%–3.4%). According to assigned risk group, rates were 2.1% (95% CI = 0.9%–4.3%) in the low-risk group, 2.2% (95% CI = 1.0%–4.1%) in the intermediate-risk group, and 2.3% (95% CI = 0.8%–5.5%) in the high-risk group.
Totals of patients in the risk groups who received radiotherapy according to the study guideline were 181 (62%) in the low-risk group (37% received more radiotherapy; 1%, less), 200 (54%) in the intermediate-risk group (29% received more; 17%, less), and 152 (86%) in the high-risk group (14% received less). Among patients receiving guideline radiotherapy, 5-year locoregional recurrence was 2.3% (95% CI = 0.8%–5.3%) in the low-risk group, 1.0% (95% CI = 0.2%–3.4%) in the intermediate-risk group, and 1.4% (95% CI = 0.3%–4.5%) in the high-risk group.
The investigators concluded, “In this study, the 5-year locoregional recurrence rate was less than 4%, which supports our hypothesis that it is oncologically safe to de-escalate locoregional radiotherapy based on locoregional recurrence risk in selected patients with cT1–2N1 breast cancer treated with primary chemotherapy, according to this predefined, consensus-based study guideline.”
Sabine R. de Wild, MD, of the Department of Surgery, Maastricht University Medical Centre+, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by the Dutch Cancer Society. For full disclosures of the study authors, visit thelancet.com.
