The effects of the following cancer chemotherapeutic agents on serum hormonal levels, estrous cycles, and endocrine organs were studied in mature, normal Sprague-Dawley rats by radioimmunoassay, vaginal smear examination, and organ weight end point: estradiol mustard (NSC 112259), testosterone mustard (NSC 112260), phenestrin (NSC 104469), methotrexate (NSC 740), 5-fluorouracil (NSC 19893), vinblastine (NSC 49842), vincristine (NSC 67574), nitrogen mustard (NSC 762), and 1,3-bis(2-chloroethyl)-1-nitrosourea (NSC 409962). Following 2 weeks of treatment, estradiol-17β levels were markedly elevated by all compounds except testosterone mustard and nitrogen mustard, which caused a decrease. Estrone levels were elevated by methotrexate, 5-fluourouracil, vinblastine, vincristine, nitrogen mustard, and 1,3-bis(2-chloroethyl)-1-nitrosourea, but were lowered by estradiol mustard. Progesterone levels were elevated only by estradiol mustard and testosterone mustard and were not affected by other compounds. Prolactin surge during proestrus was suppressed by phenesterin and methotrexate. Luteinizing hormone levels were lowered by methotrexate and nitrogen mustard. Estrous cycles of rats treated with estradiol mustard were arrested at proestrus, and the uterine and pituitary weights of these rats markedly increased. Uterine weight loss was significant following treatment with testosterone mustard, 5-fluorouracil, and nitrogen mustard. Thyroid weight was reduced by all compounds except methotrexate and vinblastine. Significant increases in pituitary weights occurred following treatment with all compounds except 1,3-bis(2-chloroethyl)-1-nitrosourea. The effects on ovarian and adrenal weights were minimal although significant by some compounds. Thus, in addition to their direct antitumor effects, these agents also produce changes in endocrine system which may be synergistic or antagonistic to the chemotherapy of endocrine-responsive neoplasms.

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This study was supported by Contract NO1-CB-50006 from Breast Cancer Program Coordinating Branch, Division of Cancer Biology and Diagnosis, National Cancer Institute. An abstract of this study has been published (15).

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