Occurrence of thyroid carcinoma in Dutch patients with familial adenomatous polyposis. An epidemiological study and report of new cases.

OBJECTIVES

To assess the occurrence of thyroid cancer in Dutch patients with familial adenomatous polyposis (FAP) and to discuss the value of surveillance.

DESIGN

Retrospective analysis of medical records.

SETTING

The data were collected from the Dutch FAP registry.

PARTICIPANTS

601 patients with FAP, 339 males and 262 females.

RESULTS

The registry contained four female cases with a thyroid carcinoma. The mean age at diagnosis was 30 years (range: 16-46). In two patients it was the presenting symptom of FAP. None of the women died from their thyroid carcinoma during a mean follow-up of 13 years (range: 6-31). The histology revealed one papillary carcinoma, one follicular carcinoma and two mixed papillary/follicular carcinomas. The relative risk (RR) of developing thyroid carcinoma compared with the general Dutch population was 23 (95% confidence interval: 9-61). At the age of 60 years, the cumulative risk (CR) of thyroid carcinoma for female FAP patients was 2.8%.

CONCLUSIONS

Young female FAP patients have a significantly increased RR to develop a thyroid carcinoma. It may even be the presenting symptom of FAP. As the CR of thyroid carcinoma is low and the prognosis seems to be good, we recommend only periodical physical examination of the thyroid.