For patients with early-stage breast cancer, surgery followed by adjuvant chemotherapy is a standard of care. However, because of the toxicities associated with chemotherapy, many patients receive reduced or modified doses. A new study sought to evaluate the impact of full versus modified-dose adjuvant chemotherapy on breast cancer survival. The investigators analyzed data from 1,302 women with stage I-III HER2-negative breast cancer who were included in the Alberta Cancer Registry. All patients included in this analysis received between 4 and 6 cycles of an adjuvant chemotherapy regimen that included 5-fluorouracil, epirubicin, cyclophosphamide, and docetaxel (FEC-D).
Reduced doses of chemotherapy were received by 16% of patients, while the remaining 84% received at least 85% of their total intended chemotherapy dose. Patients receiving 85% or more of their total dose were younger than patients receiving reduced doses (54 years vs 57 years; P < .01), were more likely to be premenopausal (44.5% vs 28.2%; P < .001), and had lower rates of comorbidities by the Charlson comorbidity index (P < .001). Patients who received at least 85% of their total chemotherapy dose had significantly higher 5-year disease-free survival (DFS; 86% vs 79%; P = .025) and overall survival (OS; 89% vs 81%; P = .001) compared to patients who received reduced doses. The relationship between reduced dose and decreased survival remained when adjusted for confounding factors. Dose reduction early in treatment, particularly in the first 3 cycles, was associated with a greater negative impact on DFS (P = .002) and OS (P < .001) than dose reduction in later cycles. Delayed dosing did not impact outcomes, nor did use of granulocyte colony stimulating factor (GCSF).
The investigators concluded that dose reductions early on during adjuvant chemotherapy lead to decreases in long-term survival in patients with stage I-III breast cancer. This highlights the importance of maintaining chemotherapy dose early in treatment. As dose reductions are often related to toxicity, use of GCSF early in treatment may be of use in decreasing the need for dose reductions. However, prospective studies evaluating the impact of chemotherapy dose on long-term outcomes will be needed to verify this observational study.
Read more about this study on Medscape Oncology.