A reassessment of the role of breast tumor aromatization.

While the role of estrogens in the maintenance of human breast carcinoma has been firmly established for many years, the sources of this estrogen remain unresolved. Input-output analysis of steroid uptake by breast carcinomas showed no specific uptake of estrogens from blood. Based on the detection of the necessary enzyme systems. Adams and Wong proposed that breast tumors could function as "paraendocrine organs" capable of producing sufficient estradiol (E2) to stimulate their own growth (Adams, J. B., and Wong, M. S. F. Lancet, 2: 1163, 1968). Using the reported values for the concentration of C19 steroid precursors and the rho TTC19-E2 values one can estimate that the contribution of in situ aromatization to the tumor estrogen pool is quite small.