Abstract
Background: Hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) is the most common biologic subtype of breast cancer. Although adjuvant therapy has demonstrated a survival benefit in clinical trials, its use is poorly understood in the real-world among elderly breast cancer patients since age is a barrier to receiving adjuvant therapy. An examination of treatment patterns and outcomes associated with receipt of adjuvant/neoadjuvant therapy among elderly HR + HER2-breast cancer patients was undertaken. Methods: There were 18,470 HR + HER2-breast cancer patients from the linked SEER-Medicare database. Patients were diagnosed with stage I-III disease between 1/1/2007-12/31/2011, ≥66 years, enrolled in Medicare Parts A, B and D, and underwent breast cancer surgery after diagnosis. Time-varying Cox proportional hazards regression assessed overall survival. Results: There were 13,670 (74%) patients treated with adjuvant/neoadjuvant therapy and 4800 (26%) untreated. Compared to treated patients, untreated patients were older, had earlier stage, lower grade, smaller tumors, poorer performance, higher comorbidity score, and less use of a 21-gene recurrence score (RS) assay (p n RS assay was associated with lower risks. The Cox model showed a 48% higher risk of death in untreated compared to treated patients. In a subset of 8967 patients with stage I disease, tumor size Conclusions: Older patients with favorable clinical characteristics (earlier stage, smaller tumor, lower grade) are less likely to be treated and have a higher risk of death compared to adjuvant/neoadjuvant treated patients. An unmet need among older breast cancer patients persists.
Highlights
Breast cancer is the most common invasive cancer in women and the second leading cause of death from cancer among women in the United States [1]
The decision to add chemotherapy to adjuvant endocrine therapy is individualized based on patient factors such as age, tumor size, tumor grade, lymph node involvement, and the results of prognostic multigene assays like the 21-gene Recurrence Score (RS) assay [9] [10] [11]
In regards to treatment rates in association with RS assays; the rates of sequential chemotherapy followed by hormonal therapy decreased from 6% in 2007 to 5% in 2011, the use of hormonal therapy increased from 60% in 2007 to 73% in 2011, and chemotherapy only remained consistent at 11% throughout the time period (p = 0.0017; data not shown)
Summary
Breast cancer is the most common invasive cancer in women and the second leading cause of death from cancer among women in the United States [1]. Hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) is the most common biologic subtype of breast cancer occurring in post-menopausal women and men [3], and accounts for about 73% of incident cases [4]. Compared to treated patients, untreated patients were older, had earlier stage, lower grade, smaller tumors, poorer performance, higher comorbidity score, and less use of a 21-gene recurrence score (RS) assay (p < 0.0001). In the survival model, increasing age, stage, tumor size, tumor grade, comorbidity score and poor performance were significantly associated with higher mortality risks, while use of an RS assay was associated with lower risks. In a subset of 8967 patients with stage I disease, tumor size < 2.0 cm and grade 1/2; untreated patients had a 22% higher risk of death compared to treated patients.
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