Hematologic toxicity and dose intensity in older patients with colorectal cancer receiving systemic chemotherapy

Abstract

4052 Background: While the risk of colorectal cancer (CRC) as well as comorbidities increase with age, systemic chemotherapy has become a mainstay of treatment across age groups. Trends in chemotherapy dosing, toxicity, and supportive care for patients with CRC from a nationwide study were examined. Methods: Patients with CRC (N=521), including 255 ≥ 65 years of age, were prospectively registered at 115 US community oncology practices. Primary outcomes included anemia (hemoglobin <10g/dL), thrombocytopenia (platelets <75x109/L), febrile neutropenia (FN; fever/infection and absolute neutrophil count (ANC) nadir <1x109/L) or severe neutropenia (SN; ANC <5x109/L), and both planned and actual relative dose intensity (RDI) compared to standard regimens. Differences among patients age 18–64 (50.5%) and age ≥ 65 (49.5%) were compared. Results: No significant differences in disease stage or type of chemotherapy regimen were reported between older and younger patients. Older patients in this study, however, were more likely to have comorbid conditions (p=0.048) and significantly poorer ECOG performance status (p=0.0004) than younger patients. CRC patients ≥ 65 years of age compared with patients <65 experienced significantly higher rates of neutropenic complications: 12.1% vs. 5.9% (p=0.015), anemia: 22.9% vs. 14.9% (p=0.023), and thrombocytopenia: 6.3% vs. 1.6% (p=0.007), respectively. Actual RDI <85% over four cycles was observed in 42.2% of patients with half of reductions in RDI planned from the start of chemotherapy. Although older patients with CRC were less likely to have body surface area >2 m2 than younger patients (p=0.002), no difference in average actual or planned RDI or colony-stimulating factor (CSF) use between older and younger patients was observed. Prophylactic CSF was administered in <10% in both older and younger patients. Conclusions: Older patients with CRC experienced higher rates of chemotherapy-related hematologic toxicity compared with younger patients. While CSFs have been shown to reduce the risk of SN in CRC, this study demonstrates that most patients with nonmetastatic disease do not receive CSF prophylaxis but rather undergo substantial reductions in chemotherapy dose intensity potentially compromising curative treatment. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Amgen Amgen Amgen