KEY TAKEAWAYS
- SWOG S1007 trial aimed to study the LRR in patients with low-recurrence score breast cancer and 1 to 3 involved nodes who did not receive RNI after surgery.
- The study showed that LRR between 1 and 5 years was very low in different treatment groups.
- Patients who did not receive RNI had generally low LRR rates, raising doubts about the necessity of RNI in this particular group.
- Omitting regional nodal irradiation in patients with low-recurrence score breast cancer may have little impact on locoregional recurrence rates.
The study examined the frequency of regional nodal irradiation (RNI) utilization in patients with low-recurrence score breast cancer and 1 to 3 involved nodes. Researchers identified the incidence and predictors of locoregional recurrence (LRR) and explored the connections between locoregional therapy and disease-free survival.
In the secondary analysis of the SWOG S1007 trial, researchers investigated patients with hormone receptor-positive, ERBB2-negative breast cancer who had undergone the Oncotype DX 21-gene Breast Recurrence Score assay with a result of 25 or lower. These patients either received endocrine therapy alone or chemotherapy followed by endocrine therapy. The study collected data from 4,871 patients treated in various healthcare settings.
The cumulative incidence of LRR was computed based on the locoregional treatment received. The analyses examined the correlations between invasive disease-free survival (IDFS) and locoregional therapy, considering factors such as menopausal status, treatment group, recurrence score, tumor size, nodes involved, and axillary surgery. Radiotherapy data were recorded during the initial year following randomization Of 4,871 female patients included in the study, with a median age of 57 years (range: 18-87), 3,947 (81.0%) reported receiving radiotherapy. Among the 3,852 patients who received radiotherapy and had complete information on treatment targets, 2,274 (59.0%) underwent RNI. During a median follow-up of 6.1 years, the cumulative incidence of LRR at 5 years was as follows: 0.85% for patients who received breast-conserving surgery and radiotherapy with RNI, 0.55% after breast-conserving surgery with radiotherapy without RNI, 0.11% after mastectomy with postmastectomy radiotherapy, and 1.7% after mastectomy without radiotherapy.
The observed LRR rates were similarly low in the group assigned to endocrine therapy without chemotherapy. Researchers did not find any significant difference based on RNI receipt for both premenopausal (hazard ratio [HR]: 1.03; 95% CI: 0.74-1.43; P = .87) and postmenopausal patients (HR: 0.85; 95% CI: 0.68-1.07; P = .16).
In this secondary analysis of a clinical trial, researchers investigated the use of RNI in the context of biologically favorable N1 disease. The rates of LRR remained low even in patients who did not receive RNI. Moreover, disease-free survival did not show any significant association with RNI receipt. The study suggests that omitting chemotherapy among patients similar to those enrolled in the S1007 trial is not an independent indication for using RNI.
Source:https://pubmed.ncbi.nlm.nih.gov/37410451/
Clinical Trial: https://classic.clinicaltrials.gov/ct2/show/NCT01272037
Jagsi R, Barlow WE, Woodward WA, Connolly E, Mahtani R, Shumway D, Speers C, Stecklein SR, Zeidan Y, Zhang H, Sharma P, Pusztai L, Hortobagyi GN, Kalinsky K. Radiotherapy Use and Incidence of Locoregional Recurrence in Patients With Favorable-Risk, Node-Positive Breast Cancer Enrolled in the SWOG S1007 Trial. JAMA Oncol. 2023 Jul 6:e231984. doi: 10.1001/jamaoncol.2023.1984. Epub ahead of print. PMID: 37410451; PMCID: PMC10326730.
