Histopathologic subtyping of cervical adenocarcinoma reveals increasing incidence rates of endometrioid tumors in all age groups - A population basedstudy with review of all nonsquamous cervical carcinomas in Norway from 1966 to 1970, 1976 to 1980, and 1986 to 1990

BACKGROUND. The effect of histopathologic review and subclassification on i ncidence rates for nonsquamous cell carcinoma (non-SCC) of the uterine cerv ix in the Norwegian population was evaluated. METHODS, All non-SCC from three 5-year periods (1966-70, 1976-80, and 1986- 90) were reviewed, classified, and graded. RESULTS. Incidence rates were 1.2, 1.2, and 1.7 per 100,000 for adenocarcin oma and 0.1, 0.3, and 0.5 per 100,000 for other carcinomas in the three per iods. Adenocarcinomas increased in all age groups, most markedly in women y ounger than 35 years. Incidence rates for both major subgroups of endocervi cal (EC) and endometrioid (EM) carcinomas increased for women younger than 55 years. After 1976-80, the incidence rate for EC, but not for EM, decreas ed in women older than 55 years. Endometrioid carcinoma became the dominant histologic subtype in 1986-90. Shifts toward lower clinical stages and you nger age were found for EC, EM, and carcinoma not otherwise specified (NOS) . Patients with NOS, clear cell, serous, or glassy cell/undifferentiated ca rcinoma were older, and their disease was diagnosed at higher stages. Distr ibution of International Federation of Gynecology and Obstetrics (FIGO) sta ges was. Stage I: 62%; Stage II: 21%; Stage III: 12%; and Stage IV: 5%. Dis tribution of histologic subgroups was: EC:, 24%; EM: 21%; NOS: 16%; clear c ell: 7%; adenosquamous: 7%; small cell: 6%; serous: 4%; undifferentiated: 3 %; and villoglandular carcinoma: 2%. Other subgroups were seen only sporadi cally. CONCLUSIONS, Incidence rates of non-SCC of the uterine cervix are increasin g in Norway. Improvements in diagnostic procedures may explain shifts towar d lower stage and age of patients but not the observed differences between histologic subgroups. (C) 2000 American Cancer Society.