Abstract
METHODS
In this prospective registry study (RAPCHEM, BOOG 2010-03), patients referred to one of 17 participating Dutch radiation oncology centres between Jan 1, 2011, and Jan 1, 2015, with cT1-2N1 breast cancer (with ≤3 suspicious nodes at imaging) treated with primary chemotherapy, followed by breast and axillary surgery, were included. Three risk groups, with corresponding radiotherapy guideline 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-IV. The current analysis presents the prespecified secondary endpoints of the study of 10-year isolated locoregional recurrence rate, 10-year recurrence-free interval, and 10-year overall survival. This trial is registered with ClinicalTrials.gov, NCT01279304.
BACKGROUND
Indications for postoperative locoregional radiotherapy in cT1-2N1 breast cancer after primary systemic therapy are disputed. The previously published 5-year outcomes of the RAPCHEM study showed excellent locoregional control when radiotherapy was tailored to the nodal response after primary chemotherapy. Here, we present 10-year results.
FUNDING
Dutch Cancer Society.
INTERPRETATION
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.
FINDINGS
838 patients were included in the 10-year follow-up analysis: 291 in the low-risk group, 370 in the intermediate-risk group, and 177 in the high-risk group. The 10-year locoregional recurrence rate in all patients was 2·9% (95% CI 1·9-4·2), with locoregional recurrence rates of 2·4% (95% CI 1·1-4·7) in the low-risk group, 3·2% (1·8-5·4) in the intermediate-risk group, and 2·8% (1·1-6·1) in the high-risk group. No significant differences were seen in locoregional recurrence between the groups. The 10-year recurrence-free interval for all patients was 79·2% (76·2-81·8), and the 10-year overall survival for all patients was 83·0% (80·3-85·4).