Copper Eskimos still didn't have breast cancer or cystic disease from 1946-1956 and were the last to Europeanize.
January 2, 1956
The Canadian Medical Association Journal of Toronto for 1956 (LXXV, 486-88)
That the cancer incidence has continued low in the Canadian eastern Arctic — east of Anderson River and west of Labrador — is to be inferred from an article in The Canadian Medical Association Journal of Toronto for 1956 (LXXV, 486-88) signed by Drs. Lawson, Saunders, and Cowen, which says:
“For the past 10 years we have been aware of the relative freedom of Eskimos [of the Canadian eastern Arctic] from breast cancer and cystic disease. In spite of strenuous efforts, we have so far been unable to discover one authenticated case of Eskimo breast malignancy.”