SAN ANTONIO — Several factors influenced receipt of adjuvant chemotherapy among a cohort of elderly women with breast cancer, according to study results presented at San Antonio Breast Cancer Symposium.
However, adjuvant chemotherapy appeared associated with an OS benefit regardless of many of those key factors, including age, hormone receptor status and disease stage.
“In 2018, there was an estimated 266,000 cases of breast cancer. Of these, around 90% of cases were diagnosed at local or regional stages and the majority [were] in older-aged adults,” Shreya Sinha, MD, fellow at SUNY Upstate Medical University, said during a presentation. “We believed it was important to study a large cohort of older patients to not only see if there was an improvement in OS with adjuvant chemotherapy, but also to figure out which factors led to the most benefit.”
Although the role of adjuvant chemotherapy is well-established among younger patients with early-stage breast cancer, the magnitude of benefit and trends in utilization among patients aged older than 65 years have not been well established.
Sinha and colleagues pooled data from the National Cancer Database on 160,676 women aged 65 years and older (21,743 aged older than 80 years) diagnosed with stage I to III breast cancer between 2004 and 2015.
The researchers used multivariate analysis to assess factors that predicted use of adjuvant chemotherapy. OS was calculated with Kaplan-Meier curves and HRs were estimated with the Cox proportional hazards model. Comparisons between groups were assessed with Log rank test and Pearson chi square.
Investigators identified several factors that were significantly associated with chemotherapy receipt among elderly patients. These included histology, grade, age, race, receipt of radiation therapy, type of surgery, Charlson/Deyo Comorbidity Score, disease stage and ER/PR status (P < .0001 for all).
Yet, researchers observed an OS benefit with adjuvant chemotherapy regardless of age, hormone receptor status or stage, with more benefit observed among patients with higher-stage disease (stage I, HR = 0.8; stage II, HR = 0.6; stage III, HR = 0.66).
OS was 144 months among those treated with adjuvant chemotherapy compared with 112 months among those who did not receive adjuvant chemotherapy (HR = 0.61).
Sinha acknowledged several limitations of the study, including the retrospective study design, the fact the HER-2 neu population was not well-defined, and genotype prediction scores were not taken into account.
“When we are treating our elderly population with breast cancer, we have to use the physiological age when devising a treatment plan. We also have to use chemotherapy toxicity prediction calculators to figure out how much toxicity each patient can tolerate,” Sinha said. “Geriatric assessment tools have shown accuracy in predicting the risk for chemotherapy and should be used when tailoring chemotherapy for this elderly population.” – by Jennifer Southall
Sinha S., et al. Abstract GS2-02. Presented at: San Antonio Breast Cancer Symposium; Dec. 4-8, 2018; San Antonio.
Disclosures: Sinha reports no relevant financial disclosures. Please see the abstract for all other authors’ relevant financial disclosures.