Screenings for people with Cowden syndrome (PHTS)

The main guidance

The European Reference Network on Genetic Tumour Risk Syndromes (ERN GENTURIS) published an updated cancer surveillance guideline for PHTS in July 2026, replacing its 2020 version. It was written by 17 experts from nine countries with three patient representatives, and says the checks need real commitment from patients and a coordinated team of specialists. (ERN GENTURIS, 2026) The International PHTS Consensus Guidelines Working Group published its own recommendations in 2025, and advises that people with PHTS see a multidisciplinary team at an experienced centre. (International PHTS guidelines, 2025) The European group says the two guidelines have many similarities, with differences from a longer literature search and from adapting to European health systems. (ERN GENTURIS, 2026)

Checks the guidance lists for adults

This is the 2026 European summary protocol, with the 2025 international schedule beside it. (ERN GENTURIS, 2026)(International PHTS guidelines, 2025)

Check	ERN GENTURIS 2026	International 2025
Breast MRI (women)	From 25, as for BRCA1 carriers	Every year from 25
Mammogram (women)	From 40, as for BRCA1 carriers	Every year from 40
Thyroid ultrasound	Start between 10 and 18; yearly, then every 2 to 3 years after two clear scans	First scan at 12; then every 2 to 5 years depending on findings
Thyroid blood test (TSH)	Not listed	Consider yearly from 18
Colonoscopy	Once between 35 and 40, preferably at an expert centre	Once between 35 and 40; every 1 to 3 years only with a high polyp burden
Kidney imaging	One baseline scan (MRI preferred) between 35 and 40	Ultrasound every 2 years from 35 to 40 may be considered
Womb (endometrial) checks	Yearly transvaginal ultrasound from 35 to 40 may be offered	Not routine; only as part of a clinical trial
Skin check by a dermatologist	Once at 30	Not covered (separate skin guideline planned)

Breast

The European guideline says women with PHTS should be offered breast screening that includes MRI, starting at 25 and following the schedule used for BRCA1 and BRCA2 carriers; most national BRCA1 schedules use a yearly MRI and a mammogram every 1 to 2 years from 40. After menopause, the need to continue MRI is assessed individually. It says yearly MRI has the greatest sensitivity in women with PHTS. (ERN GENTURIS, 2026) The international guidelines recommend a yearly breast MRI with contrast from 25 and a yearly mammogram with tomosynthesis from 40 until 75 to 80, then an individual decision with a breast specialist. They do not recommend breast screening for men with PHTS, or routine breast self-examination and clinical breast examination. (International PHTS guidelines, 2025) See mammogram: what to expect and dense breasts.

Thyroid

The European guideline says thyroid screening should be by ultrasound and should probably start between 10 and 18, not before 10 because cancer and benign growths are rare in that age group. Scans are yearly at first and, after two scans with no suspicious findings, every 2 to 3 years. It notes the median age of thyroid cancer in PHTS is 42 and warns about overdiagnosis of small, slow-growing thyroid cancers. (ERN GENTURIS, 2026) The international guidelines advise a first ultrasound at 12, then every 3 to 5 years if no nodules were seen, or every 2 to 3 years if small nodules needing no action were seen, and suggest considering a yearly TSH blood test from 18. (International PHTS guidelines, 2025) See thyroid cancer screening.

Colon

Both guidelines recommend one baseline colonoscopy between 35 and 40. (ERN GENTURIS, 2026)(International PHTS guidelines, 2025) The European guideline says it should preferably be done at a centre with PHTS or hereditary colorectal expertise, that later intervals depend on the number, size and type of polyps found, and that if only hamartomatous polyps or no polyps are seen, general population intervals may apply, with the option to repeat after 5 to 10 years. It says a stool test (FIT) is not recommended on its own for people with PHTS. People with a family history of early colorectal cancer may start earlier. (ERN GENTURIS, 2026) The international group does not recommend routine colonoscopy before 35 to 40, or routine upper endoscopy. (International PHTS guidelines, 2025) See screening colonoscopy: what to expect and colonoscopy after polyps.

Kidneys

The European guideline estimates the risk of kidney cancer at 3 to 9 percent by age 70 and says it is unknown whether screening helps in PHTS. It recommends one baseline scan between 35 and 40, preferably MRI, rather than regular kidney screening, unless other risk factors are present. (ERN GENTURIS, 2026) The international group, as an expert opinion with limited evidence, says an ultrasound every 2 years from 35 to 40 may be considered, and a kidney MRI may also be considered. (International PHTS guidelines, 2025)

Womb (endometrium)

The European guideline says women should probably be offered endometrial screening from 35 to 40, by transvaginal ultrasound at least once a year, with an endometrial biopsy as an option. It adds that no study has shown routine ultrasound improves outcomes, that ideally this is done within a clinical trial, and that all women with a PTEN variant should learn the early signs of endometrial cancer. (ERN GENTURIS, 2026) The international guidelines say routine endometrial screening should be offered only as part of a clinical trial; they encourage education from diagnosis or from 30 to 35 and a prompt response to abnormal or postmenopausal bleeding, which should be checked with both an ultrasound and a biopsy. (International PHTS guidelines, 2025) See endometrial cancer screening.

Skin

Almost everyone with PHTS has skin changes, nearly all of them benign. Because melanoma risk figures vary and there is no evidence that screening everyone helps, the European guideline recommends one skin check by a dermatologist at 30, with later checks based on personal risk, as in the general population. (ERN GENTURIS, 2026) The international guidelines leave skin cancer to a separate dermatology statement. (International PHTS guidelines, 2025) See skin cancer check: what to expect.

Checks for relatives

MedlinePlus Genetics says Cowden syndrome is inherited in an autosomal dominant pattern, meaning one altered copy of the gene is enough to cause it; some cases come from an affected parent and others from a new gene change. (MedlinePlus Genetics) The European recommendations apply to people with a confirmed disease-causing PTEN variant. (ERN GENTURIS, 2026) The international group says everyone diagnosed should have a full physical exam and learn the signs of the cancers linked to PHTS. (International PHTS guidelines, 2025) See family history and screening and how to collect your family health history.

Routine age-based screening

PHTS checks are added to, not instead of, the routine screenings for your age and sex; see screenings by age and gender.

Where they differ:

Thyroid start and interval. The European guideline starts between 10 and 18 with yearly scans at first, (ERN GENTURIS, 2026) while the international guidelines start at 12 with scans every 2 to 5 years depending on findings, and add a TSH blood test. The international group reports that NCCN starts yearly thyroid ultrasound at 7. (International PHTS guidelines, 2025)
Kidney imaging. The European guideline offers one baseline scan at 35 to 40, (ERN GENTURIS, 2026) while the international group says an ultrasound every 2 years from 35 to 40 may be considered. (International PHTS guidelines, 2025)
Womb checks. The European guideline says yearly ultrasound may be offered from 35 to 40, five years later than the American, international, Japanese and Danish advice, (ERN GENTURIS, 2026) while the international group keeps routine endometrial screening to clinical trials. (International PHTS guidelines, 2025)
What changed in Europe. The 2020 European guideline started breast MRI at 30, yearly thyroid ultrasound at 18 and kidney ultrasound every 2 years from 40, (ERN GENTURIS, 2020) while the 2026 update moves breast MRI to 25, thyroid scans to 10 to 18, and kidney imaging to a single scan at 35 to 40. (ERN GENTURIS, 2026)

Your doctor decides what your result means for you.

Questions people ask

What checks do adults with Cowden syndrome have?

The 2026 European ERN GENTURIS guideline lists, for women, breast MRI from 25 and mammograms from 40 as for BRCA1 carriers; for everyone, thyroid ultrasound starting between 10 and 18, a skin check by a dermatologist at 30, and one colonoscopy and one kidney scan between 35 and 40. Women may also be offered a yearly womb (endometrial) ultrasound from 35 to 40. (ERN GENTURIS, 2026)

When does breast screening start?

Both the 2026 European guideline and the 2025 international guidelines say women with PTEN hamartoma tumour syndrome should have breast MRI from age 25, with mammograms added from 40. The international group says yearly MRI and mammogram, until 75 to 80 and then an individual decision, and does not recommend breast screening for men. (ERN GENTURIS, 2026) (International PHTS guidelines, 2025)

How often is the thyroid ultrasound?

The European guideline says yearly at first, starting between 10 and 18, then every 2 to 3 years after two scans with no suspicious findings. The international guidelines say a first scan at 12, then every 3 to 5 years if no nodules were seen, or every 2 to 3 years if small nodules needing no action were seen. (ERN GENTURIS, 2026) (International PHTS guidelines, 2025)

Is colonoscopy needed every year?

No. Both guidelines recommend one baseline colonoscopy between 35 and 40. Further colonoscopies depend on what it finds: the international group says every 1 to 3 years for people with five or more adenomas or polyps of 1 cm or more. (ERN GENTURIS, 2026) (International PHTS guidelines, 2025)

Should relatives be tested?

MedlinePlus Genetics says Cowden syndrome is inherited in an autosomal dominant pattern, so each child of an affected parent has a chance of inheriting the gene change. The European guideline recommendations apply to people with a confirmed disease-causing PTEN variant, which is why relatives are offered genetic testing first. (MedlinePlus Genetics) (ERN GENTURIS, 2026)