Toxicity of the FOLFOX-6 regimen, with or without 5-fluorouracil bolus, in metastatic colorectal cancer.

Objective: Standard treatment of metastatic colorectal cancer includes oxaliplatin and 5-fluorouracil in continuous infusion. Although FOLFOX-6 is the reference combination, it is aggressive and has high toxicity. Variants such as the TTD regimen, which does not include folinic acid or 5-fluorouracil bolus, are used. This study evaluates the toxicity of FOLFOX-6 and TTD in first line treatment for metastatic colorectal cancer and its effectiveness.

Method: Retrospective observational study with patients who started treatment with FOLFOX-6 and TTD, for three years. Demographic and clinical data were collected (age, sex, chronic pathologies, molecular profile, laterality, ECOG classification and stage), as well as treatment variables (previous adjuvant chemotherapy, intentionality, number of cycles, duration and pharmacogenetic aspects) and toxicity. Objective response rate and progression-free survival were calculated.

Results: The study included 71 patients, 35 treated with FOLFOX-6 and 36 with TTD. Both groups showed similar overall toxicity profiles. FOLFOX-6 had a higher incidence of neutropenia (46% vs. 8%; p < 0.01) and mucositis (51% vs. 22%; p < 0.013). In addition, there were more treatment delays (40% vs. 11%; p < 0.05) and 5-fluorouracil dose reductions (22% vs. 14%; p < 0.05) in the FOLFOX-6 group. Deaths due to toxicity were only recorded in the FOLFOX-6 group. Effectiveness was similar in both groups.

Conclusions: The TTD regimen could be a beneficial first-line option for metastatic colorectal cancer, with lower toxicity and effectiveness comparable to FOLFOX-6. It is a safe alternative for elderly or frail patients, suitable for reduced-dose 5-fluorouracil regimen with oxaliplatin.