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Triple-Negative Breast Cancer: Which is Better, Adjuvant Chemotherapy or Radiotherapy?

Triple-negative breast cancer cell.

In patients who have been diagnosed with T1 N0 M0 triple-negative breast cancer (TNBC), age plays a role in whether chemotherapy or radiotherapy will lead to better outcomes for overall survival and breast cancer–specific survival (BCSS), according to the results of a cohort study now published in JAMA Network Open.

The investigators, led by Zhen Zhai, MD, of the Department of Breast Surgery in the First Affiliated Hospital in the College of Medicine at Zhejiang University in Hangzhou, China, enrolled 7,739 female postoperative patients diagnosed with T1 N0 M0 TNBC from March 27, 2019 to August 10, 2020 to evaluate overall survival as a primary end point and BCSS as a secondary one. The study included postoperative patients diagnosed as having T1 N0 M0 TNBC between 2010 and 2015 who were enrolled in the Surveillance, Epidemiology, and End Results (SEER) cancer registry program.

For the patients included in the overall study population, for which the average age was 59.5 years, the authors recorded a five-year overall survival rate of 91.7%. Among patients with T1 N0 M0 TNBC, any adjuvant therapy improved overall survival; however, only chemotherapy was shown to improve BCSS, with an adjusted hazard ratio of 0.657. Patients older than age 70 with T1a TNBC were more likely to receive radiotherapy instead of chemotherapy. Adjuvant radiotherapy after breast-conserving surgery was associated with better overall survival and BCSS in patients aged 70 years and older, but not in younger patients. For patients with T1c breast cancer, chemotherapy after breast-conserving surgery or other surgery improved overall survival, but only chemotherapy after other surgery improved BCSS. Higher tumor grade was associated with worse prognosis. Patients with T1a disease had grade 3 tumors and received breast-conserving surgery. More patients had grade 3 tumors in the T1c subgroup than in the T1a and T1b subgroups, whereas a higher proportion of grade 2 tumors was found in the T1a subgroup. Patients with T1a TNBC were more likely to receive only radiotherapy after surgery (43.6%), followed by no adjuvant therapy (31.4%).

"The findings of this cohort study suggest that adjuvant therapies could improve overall survival in patients with T1 N0 M0 TNBC, whereas only chemotherapy was associated with better BCSS," conclude the authors. "Older patients with early-stage TNBC may benefit from adjuvant radiotherapy. Administration of adjuvant therapies to patients with different ages and cancer stages should be discussed carefully, which necessitates guidance from updated guidelines."

For More Information

Zhai Z, Zheng Y, Yao J, et al (2020). Evaluation of adjuvant treatments for T1 N0M0 triple-negative breast cancer. JAMA Netw Open, 3(11):e2021881. DOI:10.1001/jamanetworkopen.2020.21881

Image credit: Wei Qian. Courtesy of the National Cancer Institute/University of Pittsburgh Cancer Institute

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