Pediatric Colorectal Cancer: A Heterogenous Entity

Area of Science:

• Oncology
• Pediatric Oncology
• Cancer Genetics

Background:

• Colorectal cancer (CRC) is exceptionally rare in children, often associated with poor outcomes.
• Understanding the characteristics of pediatric CRC is crucial for improving diagnosis and treatment.

Purpose of the Study:

• To characterize the clinical, histological, and molecular features of pediatric colorectal cancer patients.
• To investigate potential genetic factors and tumor biology in this rare patient group.

Main Methods:

• Retrospective analysis of pediatric CRC patients (<18 years) diagnosed between 2002-2016.
• Evaluation of clinical data, histological subtypes, microsatellite instability (MSI), and DNA mismatch repair (MMR) protein expression.
• Analysis of germline mutations and loss of heterozygosity (LOH).

Main Results:

• Five pediatric CRC patients were identified, with a mean age at diagnosis of 14.2 years; 4/5 had a family history of cancer.
• Tumors were advanced (≥pT3N2) with 3/5 showing signet ring cells/mucinous histology, correlating with family history.
• All analyzed CRCs were microsatellite stable and expressed MMR proteins; only one patient had a likely pathogenic MSH2 germline mutation.

Conclusions:

• Pediatric CRC typically presents at an advanced stage with a poor prognosis.
• These tumors exhibit heterogeneous histological and molecular profiles, suggesting diverse underlying carcinogenic mechanisms.