A 42-year-old man comes for review after his older sister was diagnosed with breast cancer linked to a BRCA1 mutation. He underwent predictive testing, which confirms he also carries a BRCA1 pathogenic variant. He feels well and asks what specific cancer he, as a male BRCA1 carrier, is more likely to develop in the future.
Which cancer risk is notably increased in this patient?
A. Colon carcinoma
B. Malignant melanoma
C. Prostate cancer
D. Retinoblastoma
E. Wilms tumour
Detailed ExplanationÂ
Answer- C. Prostate cancer.
Key concept: BRCA1 and BRCA2 are tumour-suppressor genes involved in DNA repair. When mutated, they predispose individuals to certain cancers due to accumulation of genetic damage.
Cancer risks in BRCA1-positive men
Although BRCA mutations are widely discussed in the context of breast and ovarian cancer in women, men also carry significant risks:
- ↑ Breast cancer (male) – risk is low compared to women but still markedly above the general male population.
- ↑ Prostate cancer – the most important male cancer association, with BRCA2 carrying an even higher risk, but BRCA1 also significantly raises lifetime risk and cancers tend to be more aggressive.
- ↑ Pancreatic cancer (slightly elevated, more with BRCA2).
- ↑ Risk of some gastrointestinal malignancies (limited evidence).
Why prostate cancer?
BRCA1/2 mutations impair high-fidelity DNA repair mechanisms (homologous recombination). Prostate epithelial cells with impaired DNA repair accumulate damage and undergo malignant transformation.
What cancers are not associated?
- Colon cancer → linked to APC or mismatch repair genes (Lynch syndrome).
- Melanoma → commonly associated with CDKN2A or BAP1 mutations.
- Retinoblastoma → linked to RB1 mutation.
- Wilms tumour → associated with WT1 mutation.
Extra MRCP-relevant nuggets
- BRCA mutations follow autosomal dominant inheritance.
- Men with BRCA1/2 require earlier PSA monitoring due to aggressive prostate cancer phenotype.
- BRCA2 carries a higher male cancer risk than BRCA1, but both increase prostate cancer risk.
- Male carriers should be counselled about informing offspring—each child has a 50% chance of inheriting the mutation.
Cheat Sheet (Exam-Focused)
BRCA1/2 basics
- Tumour suppressor genes → DNA repair (homologous recombination).
- Autosomal dominant inheritance → 50% transmission to offspring.
Male cancer risks
- ↑ Prostate cancer (most important).
- ↑ Male breast cancer (especially BRCA2).
- ↑ Pancreatic cancer (more BRCA2).
Not associated
- APC → colorectal cancer
- CDKN2A → melanoma
- RB1 → retinoblastoma
- WT1 → Wilms tumour
Prostate cancer features
- Often asymptomatic early (peripheral zone origin).
- DRE: hard, irregular, loss of median sulcus.
- Symptoms: hesitancy, poor flow, haematuria, bone pain (late).
Screening in BRCA male carriers
- Earlier PSA testing (from 40–45 years).
- Strong consideration for MRI-based screening due to aggressive phenotype.
Flashcards (20)
- Q: What type of gene is BRCA1?
A: Tumour suppressor gene involved in homologous recombination DNA repair. - Q: Inheritance pattern of BRCA mutations?
A: Autosomal dominant. - Q: Main cancer risk for male BRCA1 carriers?
A: Prostate cancer. - Q: Does BRCA1 increase male breast cancer risk?
A: Yes, but less than BRCA2. - Q: Which BRCA mutation carries the highest male cancer risks overall?
A: BRCA2. - Q: At what age should BRCA1 men begin PSA monitoring?
A: Around 40–45 years. - Q: Which gene is linked to colorectal cancer instead of BRCA?
A: APC or mismatch repair genes (Lynch syndrome). - Q: Which gene is associated with melanoma risk?
A: CDKN2A. - Q: Mutation causing retinoblastoma?
A: RB1. - Q: Mutation causing Wilms tumour?
A: WT1. - Q: Is pancreatic cancer risk increased in BRCA1?
A: Yes, slightly. - Q: Are prostate cancers in BRCA carriers more or less aggressive?
A: More aggressive. - Q: Where does prostate cancer usually arise?
A: Peripheral zone of prostate. - Q: Early symptoms of prostate cancer?
A: Usually none; obstruction occurs late. - Q: Typical DRE finding in prostate cancer?
A: Hard, irregular, nodular prostate. - Q: Lifetime risk for BRCA carriers to pass mutation to children?
A: 50%. - Q: What is PSA?
A: Prostate-specific antigen. - Q: Does obesity increase prostate cancer risk?
A: Yes. - Q: Does Afro-Caribbean ethnicity increase prostate cancer risk?
A: Yes, significantly. - Q: Which imaging test is increasingly used in screening BRCA carriers for prostate cancer?
A: Multiparametric MRI.
MCQs for Revision
1. A man with a confirmed BRCA1 mutation is most strongly predisposed to which malignancy?
A. Glioblastoma
B. Prostate cancer
C. Colon cancer
D. Melanoma
Answer: B
2. Which mutation is correctly paired with its associated tumour?
A. WT1 → Retinoblastoma
B. RB1 → Wilms tumour
C. APC → Colorectal cancer
D. BRCA1 → Melanoma
Answer: C
3. BRCA mutations follow which inheritance pattern?
A. X-linked dominant
B. Autosomal dominant
C. Autosomal recessive
D. Mitochondrial
Answer: B
4. Prostate cancer in BRCA1 carriers tends to be:
A. Less aggressive
B. More aggressive
C. Unrelated to mutation
D. Only present in elderly men
Answer: B
5. Which test is increasingly used for early detection of prostate cancer in high-risk men such as BRCA carriers?
A. CT abdomen
B. Abdominal ultrasound
C. Multiparametric prostate MRI
D. Chest X-ray
Answer: C
Summary
BRCA1 is a tumour-suppressor gene responsible for high-fidelity DNA repair, and mutations in this gene increase cancer risk in both women and men. Male carriers, although less frequently discussed, have a significantly higher risk of developing prostate cancer, which is often more aggressive and presents at a younger age. A modest increase in male breast cancer and pancreatic cancer risk is also recognised. BRCA mutations are inherited in an autosomal dominant pattern, meaning each child has a 50% chance of inheriting the mutation. Screening programs for male carriers typically begin PSA monitoring from age 40–45 and may include multiparametric MRI due to the aggressive tumour phenotype. Prostate cancer commonly arises in the peripheral zone and may initially be asymptomatic, delaying detection. When symptoms occur, they include urinary obstruction, haematuria or bone pain. Colon cancer is not associated with BRCA1; instead, APC or mismatch repair gene mutations cause hereditary colorectal cancer syndromes. Melanoma is linked to CDKN2A, retinoblastoma to RB1 and Wilms tumour to WT1. Understanding these specific gene–cancer associations is important in MRCP exams because many questions rely on recognising the correct tumour predisposition syndromes. Proper counselling ensures male carriers appreciate their risks and undergo appropriate surveillance. This knowledge also guides cascade testing in families and helps identify high-risk individuals early.