Background: Incidence and prognosis of cancers of the endocrine glands vary greatly by histologic type.
Methods: Population-based data from SEER registries, 1973-1987, were analyzed.
Results: Thyroid cancer accounts for most (92%) of the cancers of the endocrine glands. The four major histologic types of thyroid cancer display distinct patterns, reflecting different biologic entities. Papillary carcinoma, the most common type, occurs more frequently in women than in men and in whites than in blacks and has an early onset. Follicular carcinoma, the second most common type, shows a steady increase in incidence with age and a female preponderance but no racial disparity. Medullary carcinoma, the rare differentiated thyroid tumor, has a female excess in whites only and a slow increase in incidence with age. Anaplastic carcinoma shows few racial or sex variations and reaches a substantial level only after age 50. The prognosis also varies greatly by histologic type. The overall 5-year relative survival rate is greater than 90% for papillary and follicular carcinomas, 82% for medullary carcinoma, and less than 10% for anaplastic carcinoma. Carcinomas of the suprarenal gland and thymus are rare, accounting for about 3% of endocrine cancers each. These tumors, unlike the differentiated thyroid cancer, show no female preponderance, have a higher incidence rate in blacks, and have a poorer survival rate.
Conclusions: The marked predominance of papillary carcinoma and the continued increase in its relative frequency characterize the postgoiter era and an increased use of scintigraphy and fine needle aspiration. Underdiagnosis of small tumors may explain the observed lower incidence of papillary carcinoma in blacks.