Clinical, epidemiological and molecular aspects of patients with metastatic colorectal cancer followed in a public oncology service

Introduction: About 15 to 30% of patients with colorectal cancer present with metastatic disease at diagnosis. Of those initially diagnosed with localized disease, 20 to 50% will develop metastases. The treatment of metastatic colorectal cancer (mCRC) depends on several factors, such as the clinical performance of the patient, the laterality of the disease and the presence or absence of tumor biomarkers.

Objective: To analyze the clinical, epidemiological and molecular profile of patients with mCRC followed in a public oncology service.

Methodology: This is a cross-sectional, retrospective study, conducted through the analysis of medical records of patients with mCRC treated from June 2022 to June 2024.

Results: A total of 96 patients were evaluated, of which 52.1% were male. The mean age at diagnosis was 59.5 years, and most diagnoses occurred between 50 and 69 years (61.4%). Sixty-eight (70.8%) patients were already metastatic at diagnosis. The main sites of metastases were liver (59.3%), lungs (45.8%) and peritoneum (39.6%). There was a predominance of left colon tumors (LCT) compared to right colon tumors (RCT), with 67.7% of cases. Of the 66 patients tested for RAS/BRAF mutations, 42 (63.6%) had RAS gene mutations and 24 (36.4%) were RAS/BRAF wild-type. No patient had a BRAF gene mutation. Of the 36 patients tested for microsatellite instability, only one (2.8%) was MSI. Among those with RCT, 48.4% were RAS mutated, 22.6% were RAS/BRAF wild-type, and 29% were not tested. Among those with LCT, 41.5% were RAS mutated, 26.2% were RAS/BRAF wild-type and 32.3% were not tested. Among patients with LCT and wild-type RAS, only 16.6% received anti-EGFR therapy. Regarding the systemic treatments instituted, 80.2% of patients received chemotherapy (CT) with oxaliplatin, 45.8% received CT with irinotecan and 15.6% received isolated fluoropyrimidine. The median overall survival (OS) was 41 months. There was no difference in OS between patients with RCT and LCT (38 versus 43 months; HR = 0,88, CI 95% 0,56 – 1,40, p = 0,176).

Conclusion: Most patients were between 50 and 69 years at diagnosis, reinforcing the need to invest in screening programs for this population. Understanding tumor biology implies better management of patients with mCRC. However, clinical applicability in the context of the Sistema Único de Saúde (SUS) is still limited.

Corresponding author: Poliana leite Diniz Santos Gomes (e-mail: poly_diniz@hotmail.com).