Maintenance of dose intensity in adjuvant chemotherapy of breast cancer in patients treated outside a clinical trial - Results of a retrospective study

Background: The quality of adjuvant chemotherapy is of general interest since maintenance of total dose and total dose intensity of chemotherapy delivered influences clinical outcome. Patients and Methods: This retrospective analysis evaluated 175 patients treated for primary breast cancer outside the setting of a clinical trial in six German centres from 1991 to 1999. The data retrieved from the patients' files were analysed for treatment types, drugs given per regimen with planned and delivered doses of the drugs, dates of dose delivery, haematological and non-haematological toxicities and amount and duration of supportive therapy. Results: A total of 18 different schedules was recorded. 110 patients (62%) received a CMF-type regime and 65 patients (38%) an anthracycline-based protocol. Of the 915 total cycles 870 (95%) were effectively administered. Of the delivered cycles 100 (11.5%) were delayed by > 7 days and 20 (2.3%) had dose reductions of > 15%. An important influencing factor on relative total dose intensity was the concomitant radiation administered before or during chemotherapy (p = 0.05). Conclusions: CMF-type regimens were likely to have more dose delays compared to anthracycline-based regimens (p = 0.02) if used in the adjuvant setting. If chemotherapy is applied in combination with radiation special caution is mandatory to ensure maintenance of the delivered dose intensity.