As reported in The Lancet Oncology by Mauritz et al, 10-year follow-up of a Dutch prospective registry study (RAPCHEM: BOOG 2010–03) indicated that tailoring postoperative locoregional radiotherapy based on nodal response to primary chemotherapy was associated with maintenance of a low locoregional recurrence rate in patients with cT1–2N1 breast cancer after primary systemic therapy.
Study Details
The study used data from 838 patients with cT1–2N1 breast cancer with ≤ 3 suspicious nodes at imaging who were referred to multiple Dutch radiation oncology centers between January 2011 and January 2015. Patients had received primary chemotherapy, followed by breast and axillary surgery. Three risk groups with corresponding radiotherapy guidelines were defined: the low-risk group received whole-breast radiotherapy after lumpectomy and no radiotherapy after mastectomy; the intermediate-risk group received whole- breast or chest wall radiotherapy without regional nodal radiotherapy; and the high-risk group received whole-breast or chest wall radiotherapy and regional nodal radiotherapy of levels III to IV. The primary outcome measure was locoregional recurrence rate.
Key Findings
Among the 838 patients included in the 10-year analysis, 291 were in the low-risk group, 370 in the intermediate-risk group, and 177 in the high-risk group.
The 10-year locoregional recurrence rate among all patients was 2.9% (95% confidence interval [CI] = 1.9%–4.2%). Rates were 2.4% (95% CI = 1.1%–4.7%) in the low-risk group, 3.2% (95% CI = 1.8%–5.4%) in the intermediate-risk group, and 2.8% (95% CI = 1.1%–6.1%) in the high-risk group; no significant differences were observed among groups.
The 10-year recurrence-free interval was 79.2% among all patients. Rates were higher in the low-risk group (88.2%) than in the high-risk group (64.9%, P < .0001) and the intermediate-risk group (78.9%, P = .0025). Overall survival at 10 years was 83.0% among all patients. Rates were higher in the low-risk group (90.7%) than in the high-risk group (70.5%, P < .0001) and the intermediate-risk group (83.0%, P = .0062).
The investigators concluded: “Tailoring locoregional radiotherapy in cT1–2N1 breast cancer (with ≤ 3 nodes at imaging) to the nodal response after primary systemic therapy resulted in a low 10-year locoregional recurrence rate, with promising recurrence-free interval and overall survival. By (partially) omitting radiotherapy based on nodal response after primary systemic treatment, possible morbidity caused by the radiotherapy can be avoided, which could improve patients’ quality of life.”
Annefleur J. W. Mauritz, MD, of the Department of Radiation Oncology, Maastricht University Medical Centre, Maastricht, Netherlands, 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.
