In 1958, a cancer registry was established in Papua New Guinea for a population of 2 million who had remained in near isolation for millenia until recently. This report includes cancer data for 1970 through 1978. During those years, the registrations increased from 200 to 600. The reasons for this increase and the patterns of reporting over the entire 21-year period are examined. The data offered us opportunities to examine changes in case findings according to geography, time, and sex. Genuine differences in cancer incidence and pattern within this diverse country, mainly between the highland and lowland regions, were studied particularly concerning oral, skin, liver, and penile cancers, and Burkitt's lymphoma. The controversy remains over the relationship of oral cancer and chewing of substances other than tobacco
but in this country, at least, a chew consisting only of areca nut mixed with lime must be held suspect. With the emergence from isolation, profound socioeconomic changes are occurring in this country
the patterns of cancer must change also, and we may be seeing the beginning of this already. Possible fruitful areas for further detailed studies are indicated.