The high incidence of these “traditional” types of cancer among the Inuit is hypothesized to have a strong genetic basis. Nevertheless some also believe these cancers to be associated with practices that were arguably not common among the ancestral Inuit, such as preservation of fish and meat with salt.
Genetic markers in the present Inuit population show a shared Asian heritage, which is consistent with the higher incidence of similar types of cancer among Asians, particularly those consuming large amounts of salt-preserved foods. (The Inuit are believed to originate from East Asia, having crossed the Bering Strait about 5,000 years ago.)
The incidence of nasopharynx, salivary gland, and oesophageal cancer has been relatively stable among the Inuit from the 1950s on. More modern lifestyle-related cancers, on the other hand, have increased dramatically. Examples are cancers of the lung, colon, rectum, and female breast.
The figure below (click on it to enlarge), from Friborg & Melbye (2008), shows the incidence of more traditional and modern lifestyle-related cancers among Inuit males (top) and females (bottom).
Two main lifestyle changes are associated with this significant increase in modern lifestyle-related cancers. One is increased consumption of tobacco. The other, you guessed it, is a shift to refined carbohydrates, from animal protein and fat, as the main source of energy.
Reference:
Friborg, J.T., & Melbye, M. (2008). Cancer patterns in Inuit populations. The Lancet Oncology, 9(9), 892-900.