Abstract
Summary
To test the possibility that the hypercalcemia of human female breast cancer results from a Vit. D-like substance elaborated by the tumor, breast cancers, normal male and female breast and other tissues were assayed for Vit. D activity. Five of 6 cancers associated with hypercalcemia contained small amounts of activity; so did 3 tumors from normocalcemic women. The average activity of breast cancers was 15 ± 10 IU/g (mean ± SE). Normal male and female breast tissue contained 66 ± 14 IU/g. Two specimens of gynecomastia tissue and 2 bronchogenic carcinomas associated with hypercalcemia contained little or no activity. The small amount of Vit. D in breast cancer, a tissue which lyses bone, compared with the larger amount in normal breast tissue, which does not, makes it unlikely that Vit. D is responsible for the hypercalcemia of breast cancer.
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