Treatment Outcomes of Elderly Women with HER2-Positive Advanced Breast Cancer: Real-World Analysis

For patients with human epidermal growth factor receptor 2 (HER2)-positive advanced breast cancer, the advent of anti-HER2 therapies has substantially improved disease outcomes. Yet, in clinical trials, older patients are consistently underrepresented, with approximately 2.4% of patients aged >75 years included in the pivotal CLEOPATRA study.

Although there is a dearth of research focusing on treatment outcomes in elderly patients, the reality is that advanced age at time of diagnosis is associated with a higher likelihood of not receiving initial systemic therapy for de novo metastatic breast cancer. It has also been shown in studies that older women diagnosed with metastatic breast cancer have poorer prognostic outcomes and a shorter life expectancy. Nicole Evans of Eastern Health, Box Hill, Victoria, Australia, and colleagues examined “real world” treatment patterns and outcomes in an elderly (defined as ≥70 years of age) Australian population.

Treatment of Advanced Breast Cancer in the HER2-Positive Australian Patient (TABITHA) multisite clinical registry was used to extract data, and patients were stratified according to age (<70 and ≥70 years). A total of 319 patients were identified, including 67 (21%) patients aged ≥70 years.

The investigators noted that older patients were more likely to have an Eastern Cooperative Oncology Group performance status ≥2 (16% vs 3%; P <.001). No significant differences in hormone receptor status, de novo metastatic presentation, or presence of visceral disease between groups were observed. A similar percentage of patients in each group received first-line HER2-directed therapy (85% vs 93%; P = .054), and the duration of therapy was not significantly different between groups (16 months vs 22 months; P = .70). Although there was no difference between groups in the proportion of patients who were treated with first-line chemotherapy, older patients showed shorter duration of chemotherapy (2.7 months vs 3.5 months; P <.02). In younger patients, median overall survival was significantly longer at 82 months compared with 42 months (P <.001). Overall adverse event rates were higher in the older group (34% vs 20%; P = .04), including cardiotoxicity (7% vs 0.9%; P = .02) and on-treatment deaths (5% vs 0%; P = .01), in the first-line setting.

Despite having similar treatment patterns and disease characteristics, elderly patients with HER2-positive advanced breast cancer demonstrated shorter chemotherapy durations, poorer overall survival, and increased rates of adverse events. To improve outcomes in the elderly HER2-positive population prospective studies are necessary.

Source: Evans N, Anton A, Wong R, et al. Real world outcomes in elderly women with HER2 positive advanced breast cancer. Presented at: 2020 San Antonio Breast Cancer Symposium, December 8-11, 2020. Abstract PS6-35.