Introduction: Breast cancer (BC) is the most diagnosed tumor among women worldwide. The aim of this study was to investigate the incidence and causes of low relative dose intensity (RDI) < 85% for taxane-based chemotherapy regimens used in the treatment of BC in Sultan Qaboos University Hospital (SQUH).
Methods: This was a retrospective study that included 303 BC patients, treated with taxane-based chemotherapy protocols at SQUH. RDI was calculated for each chemotherapy regimen and causes and predictors of low RDI < 85% were identified. Prophylactic and therapeutic supportive measures for certain toxicities were studied.
Results: 50.8% of the patients had neoadjuvant chemotherapy, 38% had adjuvant chemotherapy, and 11.2% of patients were given palliative treatment. AC-T and AC-THP were the most used regimens (40.3% and 17.2%). Mean RDI of used taxane-based chemotherapy regimens was 93.4%. Dose delays, dose reductions, and treatment discontinuation occurred in 36.6%, 14.8%, and 11.5%, respectively. Thirty-eight patients (12.5%) had low RDI < 85% which was reduced to 9.9% after the use of an alternative taxane. Age and chemotherapy intent were significant risk factors. 83.8% received primary granulocyte colony stimulating factor.
Conclusion: An optimal RDI greater than 85% was achieved in most cases. Furthermore, prophylactic and therapeutic supportive measures were widely used.
Keywords: Taxanes; breast cancer; chemotherapy; relative dose intensity; toxicities.