Characteristics of colorectal patients who discontinued oxaliplatin therapy.

Abstract

e15155 Background: The 3rd generation platinum-based drug, Oxaliplatin, is indicated for treatment of stage II-IV colorectal cancer (CRC). Oxaliplatin combination with Fluorouracil and Leucovorin (FOLFOX) yields a 5-year disease free survival rate of 78%. Oxaliplatin use is limited by dose-limiting side effects such as neurotoxicity, peripheral neuropathy, and hepatotoxicity. Between 60 and 95% of Oxaliplatin treated patients experience neurotoxicity. The incidence of neuropathy varies between 4 and 98%, and of hepatotoxicity between 10 and 50%. There are few effective treatments to prevent or modulate neurotoxicity although infusions of calcium and magnesium may be beneficial. We sought to understand the factors that influence the discontinuation of Oxaliplatin. Objectives: 1) Determine the characteristics of CRC patients who discontinued chemotherapy involving Oxaliplatin; and 2) Examine metabolic panel monitoring among CRC patients. Methods: A retrospective chart review of newly-diagnosed adult patients with CRC stages II, III, and IV at Sanford Health. We used SAS v.9.4 to analyze demographic and clinical data. All P were two-sided, and P < .05 were considered significant. IRB approval was obtained from Sanford Health and the University of North Dakota. Results: Data for 197 patients who received chemotherapy involving Oxaliplatin were studied. The mean [SD] age at diagnosis was 58.4 [± 12.9]. The majority 117 (59%) were male and 188 (96%) were White. 48% of patients had stage III and 35% had stage IV disease. 167 (85%) of patients received FOLFOX therapy. 56 (30%) discontinued Oxaliplatin. The median [range] number of cycles of chemotherapy completed before discontinuing Oxaliplatin was 8 [1-16]. Relative to patients who did not discontinue, patients who discontinued were significantly more likely to have of the descending colon (46% vs. 38%; P=0.023). Discontinuers were significantly more likely to experience moderate to severe symptoms (42% vs. 25%; P=0.032). Only 25 (13%) of patients had serum magnesium measured prior to starting chemotherapy. However, the median [range] serum potassium was significantly lower among discontinuers prior to starting chemotherapy (3.9 [3.2-5.3] vs. 4.1 [2.8-8.1]; P=0.023). Among patients (92%) who developed some form of peripheral neuropathy, the mean [SD] serum calcium was significantly lower among discontinuers (9.22 ± 0.52 vs. 9.40 ± 0.49; P=0.044). Conclusions: This study showed that serum potassium and calcium were significantly lower among patients who discontinued Oxaliplatin. Magnesium was measured rarely.