Early-onset Colorectal Cancer in a Patient with Li-Fraumeni Syndrome: A Case Series and Literature Review.

Screening for colorectal cancer (CRC) in individuals with Li-Fraumeni syndrome (LFS) typically recommends initiating colonoscopy at 25 years old. We herein report a case of LFS with dual CRC and liver metastasis diagnosed before the recommended screening age. A 17-year-old boy with a history of sarcoma underwent colonoscopy, revealing 2 advanced CRCs: neuroendocrine carcinoma in the descending colon and adenocarcinoma in the rectum, each displaying distinct histological features. In addition, a TP53 missense mutation (p.His193Arg) was detected by a detailed genetic examination. LFS is associated with a heightened risk of rapid progression to invasive carcinomas due to TP53 variants. Therefore, earlier initiation of colonoscopy screening may be necessary for patients with LFS.