The Impact of Chemotherapy Schedule Modification on Survival Outcome among Breast Cancer Patients Receiving Adjuvant or Neoadjuvant Treatment Modalities

Chemotherapy schedule has been reported to increase the risk of suboptimal outcomes among cancer patients receiving chemotherapy with variying outcome between treatment modality. This study investigates the Overall Survival (OS) and Hazard of Death (HR) of breast cancer patients with chemotherapy schedule modification stratified against adjuvant (ACT) and neoadjuvant (NACT) treatment modalities. The data required for this study was extracted from hospital based registry. Those patients included in the study were adult female patients receiving chemotherapy between 2013 and 2017 and completed all six chemotherapy cycles. Patients who completed all cycle with a cumulative length of delay < 7 days was categorized as 'no schedule modification' and patients who completed all cycle with the cumulative length of delay ≥ 7 days were categorized as 'with schedule modification'. The Kaplan-Meier estimator was used to estimate survival curves for each covariate and the log rank test was used to evaluate the differences in survival times for each category. Among 124 patients included in the study,93 patients were censoredand 31 events was observed, providing an OS of 75.0% with a mean survival of 54.09 months (95% CI 49.36-58.83). There was significantly higher survival (p < 0.001) in ACT treatment (83.9%) and higher mortality in NACT treatment modalities (51.6%). Among ACT treatment modality, those with no schedule modification had a significant proportion of patients surviving(p = 0.04) compared to patients with schedule modification . The OS was significantly different between age (p = 0.013), stage (p = 0.022) and chemotherapy (p = 0.002) and no significant difference in the distribution in NACT modality. Our finding suggests that patients with advanced-stage might have better survival implications when the chemotherapy schedule is optimized. Thus, the risk versus benefit of schedule modification must be carefully managed to ensure optimal chemotherapeutic outcomes while balancing the concurrent toxicity.