Severe hypertriglyceridemia during adjuvant capecitabine in a patient with factor V Leiden thrombophilia: a case report

Occurrence of Colorectal Cancer (CRC) in patients with pre-existing cardiovascular or thrombotic conditions make oncologic decisions and management strategies significantly challenging. An oral chemotherapy drug widely used for CRC in adjuvant, neoadjuvant, and metastatic settings is Capecitabine, an oral fluoropyrimidine. Despite its well-established safety profile, rare metabolic adverse events, such as severe hypertriglyceridemia (HTG), may occur complicating the patient clinical course. Here, we report the case of a 50-year-old man with a longstanding history of thrombophilia (factor V Leiden mutation) who was diagnosed with stenosing sigmoid colon adenocarcinoma under oral anticoagulant treatment (vitamin K antagonists). He underwent laparoscopic left hemicolectomy followed by adjuvant capecitabine therapy. Shortly after treatment initiation, he developed marked HTG, requiring treatment discontinuation, lipid-lowering therapy, multidisciplinary reassessment, and subsequent dose adjustment. The persistent post thrombotic syndrome required continuous anticoagulation. However, oncologic treatment was completed, metabolic abnormalities were progressively controlled, and no disease recurrence was observed. Capecitabine may cause rare HTG. In high-risk patients, strict metabolic monitoring and cardio-oncologic management ensure both chemotherapy efficacy and safety.