[6078] Dose intensity and hematologic toxicity in older breast cancer patients receiving systemic chemotherapy.

Shayne M, Culakova E, Wolff DA, Poniewierski MS, Lyman GH.. University of Rochester School of Medicine Dentistry, Rochester, NY

Background: Controlled clinical trials have provided limited data on hematologic toxicity and chemotherapy dose intensity in elderly breast cancer patients. This study evaluated patient and treatment characteristics that contributed to hematologic toxicity in breast cancer patients age 65 treated in the community setting.
Methods: A prospective study of 115 randomly selected US community oncology practices was undertaken between March 2002 and March 2005 that included 283 breast cancer patients 65 years of age. Patients were enrolled prior to initiation of at least four cycles of chemotherapy. Data gathered on each patient included information on hematologic toxicity, chemotherapy dosing, and patient characteristics such as comorbidities, and Eastern Cooperative Oncology Group performance status (ECOG PS). Primary outcome measures included: grade 2 or higher anemia (Hgb < 10g/dL) and thrombocytopenia (platelets <75 x 10⁹/L), severe neutropenia (SN; neutrophils < 0.5 x 10⁹/L or white blood cell count <1 x 10⁹/L), febrile neutropenia (FN), and both planned and actual relative dose intensity (RDI) compared to standard regimens. Univariate and multivariate logistic regression analyses were performed to compare the difference among patients age 65-69 (45%), 70-74 (29%), 75-79 (18%), and 80-88 (8%).
Results: To date, 283 consecutive breast cancer patients 65 years of age have been enrolled in this prospective registry. Approximately 74% of the patients had potentially curable, non-metastatic disease and 24% had a history of prior chemotherapy. ECOG PS <2 was seen in 92% of the patients, while 95% of patients had <2 comorbidities. Nineteen percent of patients received prophylactic colony stimulating factor (CSF). SN or FN over the first four cycles of chemotherapy occurred in 169 (60.6%) patients. Planned RDI was calculated in 269 (95%) patients and actual RDI was defined in all the patients. The mean actual RDI was 87% overall, with 83 (31.4%) patients receiving <85% of standard dose intensity. RDI <85% was more common in patients with non-metastatic disease compared to patients with metastatic disease (P=0.0001), ECOG PS 0 or 1 compared to 2 (P=0.009), history of prior chemotherapy (P=0.007), and non-anthracycline-containing regimens (P=0.01). Hematologic toxicity was not dependent upon increasing chronological age. Patients who received anthracycline-based regimens were more likely than those who did not to experience febrile or severe neutropenia (P<0.0001), thrombocytopenia (P=0.0002), or anemia (P<0.0001). Prophylactic use of CSF was associated with less FN or SN (P<0.0001). A history of 2 comorbidities was associated with the development of anemia (P=0.0005) and thrombocytopenia (P=0.02) but not FN or SN.
Conclusions: Anthracycline-containing regimens and number of comorbidities 2 were more likely than increasing age to be associated with hematologic toxicity in this cohort of older breast cancer patients.

Sunday, December 17, 2006 7:00 AM

Poster Session VI: Treatment: Chemotherapy – General (7:00 AM-9:00 AM)