Breast cancer in Greenland--selected epidemiological, clinical, and histological features.

Fifty-seven breast cancers were diagnosed among indigenous Greenlandic women from 1950 to 1974. An additional 22 cases registered between 1975 and 1979 represent a minimum number and were only used as basis for minimum incidence rates. Changes in age-adjusted rate, age-specific incidence pattern, and relative risk were consistent with an upward shift from a population of low risk between 1950 and 1969 to one of intermediate risk from 1970 onward, a finding that relates well to increased urbanization and westernization. The risk of breast cancer in Greenland may be associated with consumption of saturated fats but is seemingly not correlated to total fat intake which has always been on a par with high-risk Danish levels. An association with diet may in reality have been stronger than suggested but weakened by a counterbalancing effect of high fertility, especially in the youngest age groups. Evaluation of histological features and survival did not suggest differences which could favorably compare with findings in white population groups contrary to reported results from the population of Japan, also one of low risk and of mongoloid origin. Further studies should consider dietary intakes, endocrine variations, and breast fluid secretion with special attention to girls at the age of menarche.