Patterns of toxicity in older patients with breast cancer receiving adjuvant chemotherapy.

OBJECTIVE: To retrospectively determine the relationship of age to toxicity from adjuvant chemotherapy for breast cancer.

DESIGN AND METHODS: We identified 1,405 consecutive patients age 65 or older with primary invasive breast cancer who were seen at Memorial Sloan-Kettering Cancer Center from January 1998 to December 2000. Patients selected from this cohort for analysis were aged 65 or older at diagnosis; received their follow-up care at Memorial Sloan-Kettering Cancer Center; had stage I, II, or III breast cancer; and received adjuvant chemotherapy consisting of CMF (cyclophosphamide, methotrexate, and 5-fluorouracil), an anthracycline-based regimen (AC [doxorubicin and cyclophosphamide], or AC-T [AC and paclitaxel or docetaxel]). Exclusion criteria included prior chemotherapy or previous breast cancer.

RESULTS: One hundred thirty-two patients were included in this study, with a mean age of 70 (range 65--79). Comorbidity measured by the Charlson comorbidity index was low: score 0 (83%), 1 (12%), 2 (5%); with stages: I(18%), IIA (41%), IIB (27%), IIIA (8%), IIIB (6%), T1Nx (1%). Patients receiving an anthracycline-based regimen were more likely to experience grade 3 or 4 toxicity (p=0. 01), require hospitalization (p<0.001), and/or develop febrile neutropenia (p<0.001). Treatment delays due to myelosuppression occurred more frequently in patients receiving CMF (p<0.001). The type of chemotherapy regimen (anthracycline compared to CMF) was a better predictor for toxicity than increased age or comorbidity score.

CONCLUSIONS: In this cohort of older patients with breast cancer, the risk for toxicity from adjuvant chemotherapy depended more on the type of regimen (anthracycline vs. CMF) than the patient's chronological age.