Relative dose intensity delivered to patients with early breast cancer: Canadian experience

Abstract

Adjuvant chemotherapy for early breast cancer improves disease-free and overall survival in pre- and postmenopausal women. The importance of maintaining relative dose intensity (RDI) is well-known; however, little information is available from routine clinical practice regarding how well dose intensity is maintained with modern chemotherapy regimens.In a retrospective review of patients undergoing chemotherapy for early breast cancer at a single institution in Canada from January 2006 to November 2007, a total of 263 patients received one of the following regimens:AC-T [doxorubicin (Adriamycin: Pharmacia, Kalamazoo, MI, U.S.A.)-cyclophosphamide, paclitaxel (Taxol: Bristol-Myers Squibb, Princeton, NJ, U.S.A.)]FEC-100 (5-fluorouracil-epirubicin-cyclophosphamide)FEC-D (5-fluorouracil-epirubicin-cyclophosphamide, docetaxel)Overall, only 14.4% of patients had a RDI less than 85%. Dose delay or reduction (or both) occurred in 46%, 37%, and 20% of patients receiving fec-100, ac-t, and fec-d respectively. Optimal RDI was delivered to 96%, 95%, and 70.7% of patients for ac-t, fec-d and fec-100 regimens respectively. Patients over 65 years of age accounted for 14% of the total cohort and were more likely to receive a suboptimal RDI than were patients younger than 65 years of age (35% vs. 6.6%).Optimal chemotherapy RDI (>85%) for early breast cancer can be achieved at an academic cancer centre. This goal is less often accomplished in elderly patients, and thus a proactive approach is required for managing toxicity in that population.

Keywords: Early breast cancer; adjuvant chemotherapy; relative dose intensity.

FIGURE 1

Dose delay, dose reduction, and relative dose intensity (rdi) for the chemotherapy regimens. fec-d = 5-fluorouracil(5fu) epirubicin cyclophosphamide, docetaxel; act-t = doxorubicin (Adriamycin: Pharmacia, Kalamazoo, MI, U.S.A.) cyclophosph-amide, paclitaxel (Taxol: Bristol Myers Squibb, Princeton, NJ, U.S.A.); fec-100 = 5fu, epirubicin, cyclophosphamide.

FIGURE 2

Febrile neutropenia (Feb/Neu) and relative dose intensity (rdi) in the study population, by patient age.

FIGURE 3

Rate of febrile neutropenia (feb/neut) by chemotherapy regimen. fec100 = 5-fluorouracil (5fu) epirubicin cyclophosphamide; fec-d = 5fu epirubicin cyclophosphamide, docetaxel; ac-t = doxorubicin (Adriamycin: Pharmacia, Kalamazoo, MI, U.S.A.) cyclophosphamide, paclitaxel (Taxol: Bristol Myers Squibb, Princeton, NJ, U.S.A.).