INCIDENCE OF THYROID-CANCER IN NEW-CALEDONIA, SOUTH-PACIFIC, DURING 1985-1992

This study was designed to estimate the incidence and describe charact eristics of thyroid cancer among several ethnic groups in New Caledoni a, South Pacific. The authors located all of the new pathology diagnos es of primary thyroid cancer that occurred in the 164,173 inhabitants (1989 census) from January 1985 to December 1992. Subject and disease characteristics were abstracted from medical records, and histology wa s classified according to the World Health Organization's histologic c lassification of thyroid cancer. The average annual rate of thyroid ca ncer was 9.1/100,000 population (119 subjects). The highest rates were observed in the Island of Lifu (31.5/100,000). The incidence was high er in females than in males (age-adjusted rate ratio = 7.83; 95% confi dence interval (CI) 4.47-13.58) and in Melanesians than in other ethni c groups, especially in subjects aged 45-54 years (rate ratio = 8.27; 95% CI 3.36-20.35) and 55-64 years (rate ratio = 8.83; 95% CI 3.21-24. 32). Most cancers were papillary (82 subjects); for follicular cancers , the increased risk among Melanesians was more marked after 44 years of age. Melanesians were also more likely to have a metastatic tumor t han were other ethnic groups (rate ratio = 2.99; 95% CI 1.64-5.45). Wi th the highest incidence rates ever reported, thyroid cancer is a majo r public health problem for Melanesians of New Caledonia.