Survival outcomes associated with chemotherapy-induced neutropenia in the adjuvant treatment of colorectal cancer with FOLFOX.

Abstract

81 Background: Patients undergoing adjuvant treatment with FOLFOX for colorectal cancer (CRC) are at risk of developing chemotherapy-induced neutropenia (CIN). We assessed survival outcomes in patients who develop CIN in this setting. Methods: We performed a retrospective chart review of patients with CRC treated with FOLFOX at our institution in Canada from 2013 to 2015. The survival follow-up cut-off date was August 2021. Demographic, treatment, and outcome data were collected. CIN was defined as ANC <1.5, and all episodes of neutropenia were assumed to be the result of chemotherapy. Median OS was calculated using Kaplan-Meier product limit estimates. Results: A total of 302 patients were included (baseline demographics in the table). Median follow-up was 110 months. In the overall cohort, 174 patients (58%) had at least one episode of CIN. CIN occurred in 56% of those with stage II cancer, 43% of those with low risk stage III cancer (T1-3 and N1), and 45% of those with high risk stage III cancer (T4 or N2). Median time to first CIN event was 4.3 months. Among patients with at least one episode of CIN, the first CIN event occurred during the first 3 months of treatment in 110 (63%). Among patients with at least one episode of CIN, 79 (45%) received subsequent granulocyte colony-stimulating factor (GCSF). The median OS in the overall cohort was 171 months. For patients with and without CIN the median OS had not been reached, HR 0.84 (95% CI 0.55-1.29, p=0.43). The median OS for patients with CIN treated with and without GCSF had not been reached, HR 1.02 (95% CI 0.57-1.82, p=0.94). The 5-year survival rate for patients with and without CIN was 87% vs 77%. The 10-year survival rate for patients with and without CIN was 70% vs 64%. A trend toward improved survival in those with CIN remained when results were analyzed by cancer stage. Conclusions: Patients with CIN had a trend toward improved survival compared to those who did not have CIN. There was no indication that GCSF in the setting of CIN impacted survival. The causes for the potentially protective effect of CIN in the setting of adjuvant CRC treatment require further elucidation.[Table: see text]