Inhibition of radiogenic mammary carcinoma in rats by estriol or tamoxifen

Journal Article · Mon May 01 04:00:00 EDT 1989 · Cancer (Philadelphia); (United States)

OSTI ID:6252961

Lemon, H M; Kumar, P F; Peterson, C; Rodriguez-Sierra, J F; Abbo, K M

Mammary carcinomas have been induced by 3.5 Gy whole-body gamma radiation administered at age 40 to 50 days to virgin female Sprague-Dawley rats. In 142 irradiated controls carcinoma incidence averaged 7.8% in survivors observed less than 300 days and 38.3% of those surviving longer (P less than 0.001 by t test). Mammary cancer promotion was inhibited by two methods: estriol (E3) 638 micrograms/month (2.2 microns/mo) subcutaneously for natural life span begun 2 weeks after exposure reduced cancer incidence from 76% in controls to 48% after 331 to 449 mean days observation until neoplasia was palpable (P less than 0.02 by chi-square analysis). Uterine weights were similar in control and treated groups, and were 15% to 18% greater than uteri of nonirradiated controls from other simultaneous experiments. Six monthly 638-micrograms doses of 17 alpha ethinyl estriol (EE3) reduced tumors from 88% in controls to 64% (P less than 0.05 by chi-square analysis) and delayed cancer onset (P less than 0.01-0.04 by life table analysis). Ethinyl estradiol (EE2) after 6 months' treatment similarly delayed mammary tumor development reducing incidence to 75% (NS), with a six-fold increase in nonmammary epithelial malignant tumors. Estriol administration begun between 3 days before to 5 days after radiation did not alter mammary cancer incidence in six experiments. Monthly implantation of 2.5 mg tamoxifen (4.44 microns/mo) started 2 weeks after radiation reduced mammary cancer incidence from 83% to 14% after 307 to 314 days' observation (P less than 0.001 by chi-square analysis). Treated rats had atrophic ovaries and uteri consistent with blockade of endogenous estradiol activity.

• Research Organization: Univ. of Nebraska Medical Center, Omaha, NE (USA)
• OSTI ID: 6252961
• Journal Information: Cancer (Philadelphia); (United States), Journal Name: Cancer (Philadelphia); (United States) Vol. 63:9; ISSN CANCA
• Country of Publication: United States
• Language: English

Related Subjects

560152* -- Radiation Effects on Animals-- Animals
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BODY
CARCINOMAS
DISEASES
ELECTROMAGNETIC RADIATION
ESTRADIOL
ESTRANES
ESTRIOL
ESTROGENS
EXPERIMENTAL NEOPLASMS
GAMMA RADIATION
GLANDS
HORMONES
HYDROXY COMPOUNDS
INHIBITION
IONIZING RADIATIONS
MAMMARY GLANDS
NEOPLASMS
ORGANIC COMPOUNDS
ORGANS
RADIATIONS
RADIOINDUCTION
RADIOSENSITIVITY EFFECTS
STEROID HORMONES
STEROIDS
WEIGHT