Pancreatic Cancer Genetics: Inherited Mutations and Multifactorial Risk

Pancreatic cancer risk is influenced by inherited genetic variants, but it does not follow simple Mendelian inheritance. Instead, it arises from complex interactions between multiple genes and environmental exposures.

High-Penetrance Inherited Mutations

• BRCA2: 5–10% of familial pancreatic cancer; also breast/ovarian/prostate risk.
• CDKN2A (p16): Familial atypical multiple mole melanoma (FAMMM) syndrome; pancreatic cancer risk ~17%.
• Lynch syndrome genes (MLH1, MSH2, MSH6, PMS2, EPCAM): Colorectal/endometrial cancer predisposition; pancreatic risk elevated 8–9 fold.
• PALB2, ATM, STK11 (Peutz-Jeghers), PRSS1 (hereditary pancreatitis): Additional moderate-penetrance genes.

Polygenic & Environmental Contributors

• GWAS have identified >30 common low-penetrance variants.
• Smoking (doubles risk), obesity, diabetes, chronic pancreatitis, occupational exposures (chemicals, metals).
• Gene-environment interactions amplify risk (e.g., smoking + BRCA2).

Clinical Implications

• Genetic counseling/testing recommended for: personal/family history of pancreatic cancer, early-onset (<50), multiple primary cancers, Ashkenazi Jewish ancestry.
• Surveillance (MRI/EUS) for high-risk mutation carriers typically starts at age 50 or 10 years before earliest family diagnosis.

Most pancreatic cancers are sporadic; inherited mutations account for ~10% of cases. Risk assessment integrates genetics, family history, and modifiable factors.