Chemotherapy-induced neutropenia with FOLFOX in the adjuvant treatment of colorectal cancer.

Abstract

38 Background: Patients undergoing adjuvant treatment with FOLFOX for colorectal cancer (CRC) are at risk of developing chemotherapy-induced neutropenia (CIN). We assessed the risk of CIN and the use of granulocyte colony stimulating factor (GCSF). Methods: We performed a retrospective chart review of patients with CRC treated with FOLFOX at our institution from 2013 - 2015. Demographic and treatment data were collected. CIN was defined as ANC <1.5, and all episodes of neutropenia were assumed to be the result of chemotherapy. Results: A total of 302 patients were included (baseline demographics in Table). In the overall cohort, 174 (58%) of patients had at least 1 episode of CIN. The risk CIN was 47% in stage II, 60% in low risk stage III (T1-3 and N1), and 58% in high risk stage III (T4 or N2). Among patients with at least 1 episode of CIN, the 1st CIN event occurred during the 1st 3 months of treatment in 76%, and the median cycle of 1st occurrence was 4 (95% CI 4-5), which did not differ by stage. Among patients who had at least 1 episode of CIN, 112 (64%) had a 2nd episode at a median cycle of 9 (95% CI 8-10). Among patients with at least 1 episode of CIN, 79 (45%) received subsequent GCSF, initiated 1 cycle after the 1st CIN event 37% of the time. Among patients with at least 2 episodes of CIN (n=112), 58 (52%) received GCSF after the 1st or 2nd event. Of these, 40 patients (69%) started GCSF newly after the 2nd CIN event. Among patients starting GCSF after the 2nd CIN event, 47% initiated GCSF 1 cycle later. The median cycle at which the relative dose intensity of FOLFOX decreased to <85% was cycle 6 (95% CI 5-8) in those with no CIN events, cycle 3 (95% CI 2-4) in those with at least 1 CIN event treated with GCSF, and cycle 5 (95% CI 4-6) in those with at least 1 CIN event treated without GCSF. Conclusions: CIN is a frequent occurrence during the adjuvant treatment of CRC with FOLFOX and most often occurs in the first 3 months of treatment. While oncologists may treat some patients with 3 months of FOLFOX rather than 6, physicians must be aware of CIN regardless of the planned duration of treatment. Early initiation of GCSF may be a consideration. [Table: see text]