Genetic Testing for Prostate Cancer: BRCA, HOXB13 & Hereditary Risk
- Is prostate cancer hereditary?
- BRCA1 and BRCA2 mutations – strongest link
- HOXB13 mutation – early-onset prostate cancer
- Lynch syndrome – increased risk of multiple cancers
- Other genes – ATM, CHEK2, PALB2, NBN
- Who should get genetic testing? (NCCN guidelines)
- What results mean – positive, negative, VUS
- Implications for screening – start earlier
- Implications for treatment – PARP inhibitors
- Interactive FAQ – 9 questions about genetic testing for prostate cancer
Is prostate cancer hereditary?
Most prostate cancer is sporadic (occurs by chance), but 5-10% of cases are hereditary, caused by inherited genetic mutations passed down through families.
Hereditary prostate cancer tends to occur at a younger age (<55 years), be more aggressive, and cluster in families with other cancers (breast, ovarian, pancreatic, colon).
BRCA1 and BRCA2 mutations – strongest link
BRCA1 and BRCA2 are tumour suppressor genes best known for their role in breast and ovarian cancer. They also significantly increase prostate cancer risk.
BRCA2 mutation (most significant):
- Risk: 5-8x increased risk of prostate cancer
- Aggressiveness: More aggressive cancer (higher Gleason score)
- Age: Earlier age at diagnosis (often <65)
- Prognosis: Worse outcomes than non-carriers
BRCA1 mutation:
- Risk: 2-3x increased risk (less than BRCA2)
- Aggressiveness: Also associated with more aggressive cancer
HOXB13 mutation – early-onset prostate cancer
HOXB13 is a homeobox gene involved in prostate development. The G84E mutation is associated with early-onset prostate cancer.
- Risk: 3-5x increased risk
- Age: Early-onset (<55 years)
- Prevalence: Rare (1-2% of hereditary cases)
- Population: More common in men of European descent
Lynch syndrome – increased risk of multiple cancers
Lynch syndrome (hereditary non-polyposis colorectal cancer – HNPCC) is caused by mutations in MLH1, MSH2, MSH6, PMS2, or EPCAM genes.
- Prostate cancer risk: 2-3x increased risk
- Other cancers: Colorectal, endometrial, ovarian, gastric, urinary tract
- Age: Earlier onset than sporadic cancer
- Aggressiveness: Some studies suggest more aggressive
Other genes – ATM, CHEK2, PALB2, NBN
Several other genes have been associated with moderate increased risk:
- ATM: 2-3x increased risk; also associated with ataxia-telangiectasia
- CHEK2: 2-3x increased risk; also increases breast cancer risk
- PALB2: 2-3x increased risk; partner of BRCA2
- NBN (NBS1): 2-3x increased risk; rare
Who should get genetic testing? (NCCN guidelines)
Genetic testing is recommended for men with prostate cancer who meet any of the following criteria:
- High-risk or very high-risk localized prostate cancer (any age)
- Metastatic (Stage IV) prostate cancer (any age)
- Intraductal or cribriform histology on biopsy
- Family history:
- Two or more first-degree relatives with prostate cancer (any age)
- One first-degree relative with prostate cancer diagnosed at age <60
- Ashkenazi Jewish ancestry with prostate cancer
- Family history of BRCA-related cancers (breast, ovarian, pancreatic)
Testing for unaffected men:
- Men with a known family history of a hereditary cancer syndrome
- Men with a first-degree relative with a known mutation (BRCA, HOXB13, etc.)
What results mean – positive, negative, VUS
- Positive (pathogenic variant): A disease-causing mutation is present. Increased cancer risk. Family members may also carry the mutation.
- Negative (no pathogenic variant): No mutation found. Does not eliminate risk (may still have sporadic cancer).
- VUS (Variant of Uncertain Significance): A genetic change that is not yet known to cause disease. Most VUS are reclassified as benign over time. Does not change clinical management.
Implications for screening – start earlier
Men with hereditary prostate cancer risk should start screening earlier:
- BRCA2 mutation carriers: Start PSA screening at age 40
- BRCA1, HOXB13, Lynch syndrome: Start at age 40-45
- Strong family history (no known mutation): Start at age 40-45
- Frequency: Annual PSA and DRE
- Consider MRI: For BRCA2 carriers, consider baseline MRI at age 40-45
Implications for treatment – PARP inhibitors
Genetic testing results can guide treatment for men with advanced prostate cancer:
- PARP inhibitors (olaparib, rucaparib, niraparib): Effective in men with BRCA1/2, ATM, PALB2, or other homologous recombination repair (HRR) gene mutations
- Response rate: 40-50% in BRCA-mutated metastatic castration-resistant prostate cancer (mCRPC)
- FDA approved: Olaparib and rucaparib for HRR-mutated mCRPC
- Testing recommended: All men with metastatic prostate cancer should have genetic testing (tumour or germline)
Interactive FAQ – Genetic testing for prostate cancer
5-10% of prostate cancer cases are hereditary (caused by inherited genetic mutations).
Yes – BRCA2 increases risk 5-8x; BRCA1 increases risk 2-3x. BRCA2 carriers have more aggressive cancer.
Men with metastatic prostate cancer, high-risk localized cancer, strong family history, or Ashkenazi Jewish ancestry.
A rare mutation that increases risk of early-onset prostate cancer (<55 years). More common in men of European descent.
Yes – 2-3x increased risk. Men with Lynch syndrome should start PSA screening at age 40.
Variant of Uncertain Significance – a genetic change not yet known to cause disease. Does not change clinical management.
PARP inhibitors (olaparib, rucaparib) are effective in men with BRCA or other HRR gene mutations.
Age 40 – with annual PSA and DRE. Consider baseline MRI at age 40-45.
Most insurance plans cover genetic testing for men meeting NCCN criteria. Pre-test counselling is usually required.
Disclaimer: This information is for educational purposes. Genetic testing should be accompanied by genetic counselling. Consult a specialist at Vivekananda Hospital for personalised advice.