In a retrospective cohort study reported in JAMA Oncology, Tamirisa et al found evidence that adjuvant chemotherapy was associated with improved survival among patients age ≥ 70 years with estrogen receptor (ER)-positive, HER2-negative, node-positive breast cancer and multiple comorbidities.
The study involved data from the U.S. National Cancer Database on 1,592 patients (97% women) who were aged ≥ 70 years. Patients had a Charlson/Deyo comorbidity score of 2 or 3, ER-positive, HER2-negative breast cancer, and had undergone surgery for pathologic node-positive disease between January 2010 and December 2014. For matched analysis, propensity scores were used to match patients receiving adjuvant chemotherapy with those not receiving adjuvant chemotherapy based on age, comorbidity score, facility type, facility location, pathologic T and N stage, and receipt of adjuvant endocrine and radiation therapy.
Among the 1,592 patients, 350 (22.0%) received chemotherapy and 1,242 (78.0%) did not. Compared with those who did not receive chemotherapy, those who did were younger (mean age = 74 vs 78 years, P < .001); had larger primary tumors (pT3/T4 tumors in 20.6% vs 14.7%, P = .005); had higher pathologic nodal burden (21.4% vs 6.5% with stage pN3 disease and 52.0% vs 75.4% with stage pN1 disease, P < .001); and more frequently received other adjuvant treatments, including endocrine therapy (88.3% vs 82.5%, P = .01) and radiation therapy (67.4% vs 43.5%, P < .001).
In the nonmatched cohort, median follow-up was 41.4 months. Median overall survival in the entire cohort was 59.5 months, including 78.9 months among patients who received chemotherapy and 54.9 months among those who did not receive chemotherapy (P < .001).
A total of 592 patients were included in the propensity score–matched analysis. Median follow-up was 43.1 months. Median overall survival was 78.9 months in the chemotherapy group vs 62.7 months in the group who did not receive chemotherapy (P = .13). On multivariate analysis adjusting for other risk factors, receipt of chemotherapy was associated with improved overall survival (hazard ratio [HR] = 0.67, P = .02).
Other factors associated with improved survival on multivariate analysis in the matched cohort were receipt of endocrine therapy (HR = 0.47, P < .001) and receipt of radiation therapy (HR = 0.61, P = .006). Factors associated with poorer survival were Charlson/Deyo score of 3 vs 2 (HR = 1.94, P < .001), higher pathologic T stage (for pT4 vs pT1, HR = 3.51, P < .001), and higher pathologic N stage (for pN3 vs pN1, HR = 1.71, P = .04).
The investigators concluded, “This cohort study found that in node-positive, ER-positive elderly patients with breast cancer and multiple comorbidities, receipt of chemotherapy was associated with improved overall survival. Despite attempts to adjust for selection bias, these findings suggest that physicians carefully selected patients likely to derive treatment benefit from adjuvant chemotherapy based on certain unmeasured variables. A standardized, multidisciplinary approach to care may be associated with long-term treatment outcomes in this subset of the population.”
Nina Tamirisa, MD, of the Department of Breast Surgical Oncology, The University of Texas MD Anderson Cancer Center, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was supported in part by an award from the National Cancer Institute. For full disclosures of the study authors, visit jamanetwork.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.