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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Monday, January 24, 2022
Chang-Ok Suh, MD, PhD, of the Yonsei Cancer Center in Seoul, and colleagues reported on the effects of elective internal mammary node irradiation (IMNI) in regional nodal irradiation on outcomes in women with node-positive breast cancer in JAMA Oncology. The investigators learned that the inclusion of IMNI did not significantly improve disease-free survival in this patient population. However, they added, those with medially or centrally located tumors may derive a benefit from the use of IMNI.
The multicenter phase III randomized trial took place between June 2008 and February 2020 at 13 hospitals in South Korea. It included 735 women, with a mean age of 49, in an intention-to-treat analysis. Participants were all women with node-positive breast cancer after breast conservation surgery or mastectomy with axillary lymph node dissection. The median tumor size was 2.5 cm. All participants underwent regional nodal irradiation with breast or chest wall irradiation. Of the total population, 373 women were randomly assigned to treatment without IMNI and 362 women, with IMNI. Median follow-up was 100.4 months.
The results indicate that including IMNI in regional nodal irradiation did not significantly improve disease-free survival in patients with node-positive breast cancer. The primary endpoint, 7-year disease-free survival, did not differ between those treated without IMNI and those treated with IMNI (81.9% vs. 85.3%; hazard ratio [HR] = 0.80; 95% confidence interval [CI] = 0.57–1.14; log-rank P = .22). However, patients with medically or centrally located tumors may benefit from use of IMNI; an ad hoc subgroup analysis indicated significantly higher disease-free survival with IMNI.
Among patients with mediocentrally located tumors, the 7-year disease-free survival rates were significantly higher with IMNI (91.8% vs. 81.6% without IMNI; HR = 0.42; 95% CI = 0.22–0.82; log-rank P = .008). Further, in this subgroup, the 7-year breast cancer mortality rates were 10.2% without IMNI versus 4.9% with IMNI (HR = 0.41; 95% CI = 0.17–0.99; log-rank P = .04).
Disclosure: The study authors reported no conflicts of interest.
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