Chemotherapy dose reduction and delay in clinical practice. evaluating the risk to patient outcome in adjuvant chemotherapy for breast cancer.

Randomised clinical trials demonstrate the importance of maintaining chemotherapy dose and dose intensity in the systemic adjuvant treatment of breast cancer, and show that the strategies of dose delay and dose reduction carry the risk of suboptimal outcome. Such dose modifications are usually necessitated by the myelosuppressive effects, specifically neutropenia, thrombocytopenia and anaemia, resulting from the previous cycle of chemotherapy. The Canadian Database Initiative was designed to determine the incidence of neutropenic complications (an episode of febrile neutropenia or dose delay or reduction) and the frequency of complications by cycle of therapy using data from patients with breast cancer treated at centres across Canada. The centres used a variety of adjuvant chemotherapy regimens and the database covered the treatment of 444 patients, average age 47.7 years, who were treated between 1991 and 1996. Across all chemotherapy regimens, 42% of patients experienced at least one complication. Of those, 72% went on to have additional complications in subsequent cycles. The neutropenic complications usually occurred early in the treatment schedule.