Patient- and Tumor-Level Factors Impacting Chemotherapy Use and Effectiveness [electronic resource]

다국어 초록 (Multilingual Abstract)

Background: Chemotherapy efficacy is determined in clinical trial settings, which have limited representation of Black women. In clinical practice, there is more variation in how chemotherapy regimens are assigned and whether they are completed. Identifying factors related to chemotherapy receipt and cessation, as well as factors across which chemotherapy effectiveness may vary, may help to improve clinical outcomes among breast cancer patients.Methods: This project had three primary goals: 1) to describe real-world patterns of chemotherapy receipt and regimens in a diverse population of women with incident breast cancer, 2) to identify factors associated with cessation of chemotherapy, and 3) to explore the relationship between tumor biological characteristics and recurrence within chemotherapy treatment groups.Results: In Aim 1, both clinical characteristics and younger age at diagnosis were strongly associated with receipt of any chemotherapy and with receipt of anthracycline-inclusive regimens. There was not strong evidence of a relationship between race and receipt of chemotherapy. Next, an association was observed between both adjuvant and neoadjuvant chemotherapy regimens and early cessation of chemotherapy. There was also evidence that side effects were strongly associated with cessation of adjuvant chemotherapy. Within patient- and tumor-level characteristics, associations between these factors and cessation varied by chemotherapy regimen. Cessation of chemotherapy was associated with more breast cancer recurrence after treatment. In Aim 2, chemotherapy regimens were associated with recurrence. In unadjusted models, taxane-based treatment was associated with lower recurrence; however, after adjustment for features of disease aggressiveness, this relationship shifted and taxane-based treatment was associated with increased recurrence. Biological factors associated with DNA damage repair (p53, homologous recombination deficiency) were predictive of recurrence among women receiving anthracycline-inclusive regimens, but not among women receiving taxane-based regimens. The prognostic value of Ki-67 status did not vary by chemotherapy regimen.Conclusions: Chemotherapy receipt and cessation vary by some demographic characteristics. Effectiveness of chemotherapy may vary by adherence to treatment and by biological characteristics of the tumor.