Having node-positive, estrogen receptor–positive breast cancer indicated a greater likelihood of overall survival following chemotherapy, despite having several comorbidities, after adjustment for confounders.
An investigation of overall survival (OS) among elderly patients with estrogen receptor (ER)–positive, node-positive breast cancer resulted in findings of greater OS, despite a greater disease burden and the presence of comorbidities, following adjuvant chemotherapy, says the study published in JAMA Oncology.
“Data are lacking on the association of adjuvant chemotherapy with survival in elderly patients with multiple comorbidities and node-positive breast cancer,” the authors noted. A principal reason for this is the frequent exclusion of this age group from clinical trials.
Their restrospective cohort study analyzed data on 2,445,870 patients included in the US National Cancer Database, with 1592 meeting inclusion criteria (≥70 years; Charlson/Deyo comorbidity score of 2 or 3; ER-positive, ERBB2 [formerly HER2 or HER2/neu]–negative disease; surgery for pathologic node-positive breast cancer between January 1, 2010, and December 31, 2014). Their mean (SD) age was 77.5 (5.5) years, and 96.9% were female.
Overall, 22% of the included patients received chemotherapy, with younger age (74 vs 78 years; P < .001), larger primary tumor size (pT3/T4 tumors: 20.6% vs 14.7%; P = .005), and higher pathological nodal burden (stage pN3 disease: 21.4% vs 6.5%; stage pN1 disease: 52.0% vs 75.4%; P < .001) associated with its receipt.
There was also a greater likelihood of endocrine therapy (88.3% vs 82.5%; P = .01) and radiation therapy (67.4% vs 43.5%; P < .001) among the chemotherapy cohort.
Results were encouraging for OS, in that a positive correlation was seen between receipt of chemotherapy and OS (HR, 0.67; 95% CI, 0.48-0.93; P = .02), after adjusting for potential confounding factors. However, a statistically significant difference in median OS was not seen prior between the chemotherapy and no-chemotherapy groups: 78.9 months (95% CI, 78.9 months–not reached) vs 62.7 months (95% CI, 56.2 months–not reached; P = .13).
The nonmatched cohort had a median follow-up of 43.1 (95% CI, 39.6-46.5) months, whereas that for the entire group was 59.5 (95% CI, 55.0-65.6) months.
Age, Charlson/Deyo comorbidity score, facility type and location, pathologic T and N stage, and receipt of adjuvant endocrine or radiation therapy were used to match patients receiving chemotherapy to those not receiving it. Data were analyzed from December 13, 2018, through April 28, 2020, and the primary outcome was the link between OS and adjuvant chemotherapy.
Additional analyses revealed a worse OS was more likely in the matched cohort under the following conditions:
“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,” the authors concluded. “A standardized, multidisciplinary approach to care may be associated with long-term treatment outcomes in this subset of the population.
Possible study limitations include coding inaccuracies and underreporting of comorbidities associated with the Charlson/Deyo comorbidity score, as well as the influence of unmeasured variables and lack of breast cancer-specific survival data in the National Cancer Database.
Tamirisa N, Lin H, Shen Y, et al. Association of chemotherapy with survival in elderly patients with multiple comorbidities and estrogen receptor-positive, node-positive breast cancer. JAMA Oncol. 2020;6(10):1548-1554. doi:10.1001/jamaoncol.2020.2388