PTEN Gene: Cowden Syndrome, Cancer Risks, and What to Do
Medically reviewed by LifeShield Medical Team, Board-Certified Genetic Counselors & Clinical Advisors
Last updated February 20, 2026
Key Takeaways
- PTEN is a tumor suppressor gene that acts as a brake on cell growth. Mutations cause Cowden syndrome (PTEN hamartoma tumor syndrome).
- Women with PTEN mutations face up to an 85% lifetime risk of breast cancer, 21–28% risk of thyroid cancer, and 19–28% risk of endometrial cancer.
- Cowden syndrome also features benign growths (hamartomas) of the skin, mucous membranes, and other tissues, which can help with clinical diagnosis.
- Enhanced screening for breast, thyroid, endometrial, colorectal, and kidney cancers is recommended for PTEN carriers.
- PTEN mutations are underdiagnosed because Cowden syndrome has variable features and many physicians are unfamiliar with it.
PTEN In Plain English
The PTEN gene makes a protein that works as a growth brake for your cells. When cells receive signals telling them to grow and divide, the PTEN protein helps balance those signals by slowing growth down. This ensures cells only divide when they should and do not grow out of control. When PTEN is mutated, this brake is weakened. Cells grow and divide more readily, which increases the risk of both benign growths (hamartomas) and malignant tumors in multiple organs. The breast cancer risk for PTEN mutation carriers is comparable to that of BRCA1 carriers, making enhanced breast screening essential. For a broader understanding of hereditary cancer genes and when testing is recommended, see our guide on hereditary cancer screening.
Cowden syndrome, the main condition caused by PTEN mutations, is a multi-system disorder. In addition to cancer risk, people with Cowden syndrome often develop non-cancerous growths on the skin, in the mouth, and in other tissues. These benign features can actually be helpful for diagnosis because they provide visible clues that a PTEN mutation may be present. Many people with PTEN mutations go undiagnosed for years because their physicians are not familiar with the subtle signs of Cowden syndrome. Another hereditary syndrome with multi-organ cancer involvement is Li-Fraumeni syndrome (caused by TP53 mutations), which shares the feature of very high lifetime cancer risk across multiple organ sites.
If you receive a positive PTEN result, our guide on what to do after a positive genetic test result outlines evidence-based next steps. For help interpreting different result types, see our resource on understanding genetic test results. Because PTEN mutations follow autosomal dominant inheritance, cascade testing for family members is strongly recommended to identify relatives who may benefit from early screening. For guidance on working with a genetics professional, see what to expect from genetic counseling.
Cancer Risks Associated with PTEN Mutations
| Cancer Type | Lifetime Risk | General Population | Source |
|---|---|---|---|
| Female breast cancer | Up to 85% | 12.9% | NCCN v3.2025; Tan et al., Clin Cancer Res 2012 |
| Thyroid cancer | 21–28% | 1.3% | NCCN v3.2025; Tan et al., Clin Cancer Res 2012 |
| Endometrial cancer | 19–28% | 3.1% | NCCN v3.2025; Tan et al., Clin Cancer Res 2012 |
| Colorectal cancer | 9–16% | 4.1% | NCCN v3.2025 |
| Kidney cancer | Up to 34% | 2.2% | NCCN v3.2025; Tan et al., Clin Cancer Res 2012 |
Who Should Consider PTEN Testing?
NCCN recommends PTEN testing for individuals meeting clinical criteria for Cowden syndrome, those with a personal history of adult Lhermitte-Duclos disease, children with macrocephaly and autism or developmental delay, or when a known PTEN mutation exists in the family. Testing should also be considered for individuals with multiple early-onset cancers in PTEN-associated organs.
Should You Get Tested?
Free 60-second screener based on NCCN guidelines — no account needed
Check Your Eligibility →Questions to Ask Your Genetic Counselor About PTEN
- What is my specific PTEN variant, and how does it affect my cancer risk profile?
- What is the recommended screening schedule for all the cancers associated with Cowden syndrome?
- Should I consider risk-reducing mastectomy or hysterectomy?
- How should my thyroid nodules be monitored and managed?
- Do the benign features of Cowden syndrome require treatment?
- What does this mean for my children, and when should they be tested?
- Are there specialists who focus on Cowden syndrome management?
What a PTEN Result Means for Your Family
PTEN mutations follow autosomal dominant inheritance, meaning each first-degree relative has a 50% chance of carrying the mutation. Because Cowden syndrome is underdiagnosed and has cancer risks that can be reduced through screening, cascade testing is valuable for all at-risk family members. Some features of Cowden syndrome (such as macrocephaly) may be present from childhood, allowing for early identification. Testing children of carriers can be discussed with a genetic counselor to determine appropriate timing based on the earliest recommended screening ages.
Inheritance Pattern: Autosomal dominant
Prevalence: Cowden syndrome affects approximately 1 in 200,000 individuals (likely underestimated due to underdiagnosis)
Management Options If Positive:
- Annual breast MRI starting at age 25–30
- Annual mammogram starting at age 30–35
- Discussion of risk-reducing mastectomy
- Annual thyroid ultrasound starting at age 7–18
- Annual endometrial sampling or transvaginal ultrasound starting at age 30–35
- Risk-reducing hysterectomy after childbearing (discuss with physician)
- Colonoscopy starting at age 35–40, every 5 years (or more frequently with polyps)
- Renal ultrasound every 1–2 years starting at age 40
- Annual comprehensive dermatologic examination
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. It is based on published NCCN clinical guidelines and peer-reviewed research. Always consult a qualified healthcare provider for medical decisions. LifeShield content is reviewed by board-certified genetic counselors.