Clinical, pathologic, and demographic characteristics of colorectal cancer in patients under age 50 in a third level Mexican cancer center.

e15592 Background: Colorectal cancer (CRC) is the most common gastrointestinal neoplasia, with 1.36 million cases worldwide, representing the third cause of death due to cancer. Commonly affects people after the 6th decade of life, but recently the diagnosis in patients below 50 years is increasing. Methods: We conducted an observational, retrospective, longitudinal analysis based on medical records of patients diagnosed with colorectal cancer treated in the ABC Medical Center. Information was collected between January 2016 and January 2021. Descriptive statistics were utilized regarding data analysis. Results: We identified 289 patients with CRC, of which 23 (8.2%) patients were less than 50 years of age at diagnosis. Gender distribution reflected slightly more feminine patients (56%). The median age at diagnosis was 43 years, oncologic family history in first- or second-degree family members was documented in 31.4% of patients. At diagnosis, 22% of patients presented with an early-stage neoplasm, 31% had locoregional disease and 50% had advanced disease. Left sided disease was present in 78% of patients, 8% on the right colon and 13% were in rectum. Adenocarcinoma was found in 95% of patients. Mucinous pattern was present in 39% of patients studied, intestinal tumors in 21%, singlet ring cells in 4.3%. Histologic grade was G2: 69%. Molecular analysis was conducted in 86% of tissue biopsies. Regarding RAS mutations, 15% were positive (Gly12asp, K117N and Gly13Asp), but none in NRAS. BRAF mutation was studied in 43% of patients, no mutations were found. The search for microsatellite instability was conducted in all tumors, finding it present in only one patient (5%). At median follow up of 31.8 months, 91.4% remainded alive. Patients with early stage cancer were given adjuvant therapy in 69%. mean RFS was 40 months. All patients diagnosed in stage IV disease received systemic therapy, with a medium PFS of 10 months. First line treatment was FOLFOX in 58% of patients. Target therapy with anti-EGFR and anti-VEGF was prescribed in 83.3% and 8.3% of patients in the first line respectively. Conclusions: We found that patients under 50 years with dignosis of colorectal cancer, have a family history of cancer in up to a third of patients, the most frecuent histology reported was adenocarcinoma with mucinous pattern. We observed a low frecuency of KRAS mutations compared with literature reports. A longer follow-up is requiered to asses overall survival.