Logo of brjcancerBJC HomepageBJC Advance online publicationBJC Current IssueSubmitting an article to BJCWeb feeds
Br J Cancer. 1991 Sep; 64(3): 481–484.
PMCID: PMC1977645

Comparative study of the influence of pregnancy and hormonal treatment on mammary carcinogenesis.


Since it has been shown that pregnancy protects the mammary gland from chemically induced carcinogenesis, this study was designed with the dual purpose of determining whether treatment of young virgin rats with the placental hormone chorionic gonadotropin (hCG) mimics pregnancy-induced changes in the tumourigenic response of the mammary gland and also whether the effect induced by both pregnancy and hormonal treatments was transitory, or a more permanent one, exerting the same effect when the period of time between delivery or termination of treatment and exposure to the carcinogen is lengthened. Virgin Sprague-Dawley rats were utilised in two experimental protocols. For protocol I, 50 day-old rats were either mated (Group II), or started receiving a daily intraperitoneal injection of 100 IU hCG (Group III) at age 50. Age-matched untreated virgin rats were used as controls (Group I). Twenty-one days after either delivery or termination of treatment all the animals received an intragastric dose of 8 mg DMBA/100 gbw. For the second protocol, 50 day-old virgin rats were also mated (Group V) or were treated with hCG for 21 days (Group VI); the resting period between delivery or termination of treatment was lengthened to 63 days, at which time they received a dose of DMBA. Age-matched controls (Group IV) received DMBA only. Tumourigenesis was evaluated 24 weeks post-carcinogen administration in all the groups. Pregnancy and hCG followed by the 21-day resting period significantly depressed mammary carcinogenesis to 11% and 6% respectively, compared with 63% in control animals. When the resting period was prolonged to 63 days there was also a significant depression in adenocarcinoma incidence to 9% in pregnancy (Group IV) in which it was observed that tumour incidence was also reduced as a consequence of aging at the time of exposure to the carcinogen. These results clearly indicate that hCG is as efficient as pregnancy and significantly reduces mammary carcinogenesis, and that the protective effect of both pregnancy and hCG treatment is long-lasting and both are more efficient than aging in reducing mammary carcinogenesis.

Full text

Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (920K), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References.

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
  • Amsterdam A, Koch Y, Lieberman ME, Lindner HR. Distribution of binding sites for human chorionic gonadotropin in the preovulatory follicle of the rat. J Cell Biol. 1975 Dec;67(3):894–900. [PMC free article] [PubMed]
  • Ciocca DR, Parente A, Russo J. Endocrinologic milieu and susceptibility of the rat mammary gland to carcinogenesis. Am J Pathol. 1982 Oct;109(1):47–56. [PMC free article] [PubMed]
  • DAO TL, BOCK FG, GREINER MJ. Mammary carcinogenesis by 3-methylcholanthrene. II. Inhibitory effect of pregnancy and lactation on tumor induction. J Natl Cancer Inst. 1960 Nov;25:991–1003. [PubMed]
  • DAO TL, SUNDERLAND H. Mammary carcinogenesis by 3-methylcholanthrene. I. Hormonal aspects in tumor induction and growth. J Natl Cancer Inst. 1959 Sep;23:567–585. [PubMed]
  • Grubbs CJ, Hill DL, McDonough KC, Peckham JC. N-nitroso-N-methylurea-induced mammary carcinogenesis: effect of pregnancy on preneoplastic cells. J Natl Cancer Inst. 1983 Sep;71(3):625–628. [PubMed]
  • Grubbs CJ, Juliana MM, Hill DL, Whitaker LM. Suppression by pregnancy of chemically induced preneoplastic cells of the rat mammary gland. Anticancer Res. 1986 Nov-Dec;6(6):1395–1400. [PubMed]
  • Grubbs CJ, Peckham JC, McDonough KD. Effect of ovarian hormones on the induction of 1-methyl-1-nitrosourea-induced mammary cancer. Carcinogenesis. 1983;4(4):495–497. [PubMed]
  • HUGGINS C, GRAND LC, BRILLANTES FP. Mammary cancer induced by a single feeding of polymucular hydrocarbons, and its suppression. Nature. 1961 Jan 21;189:204–207. [PubMed]
  • HUGGINS C, MOON RC, MORII S. Extinction of experimental mammary cancer. I. Estradiol-17beta and progesterone. Proc Natl Acad Sci U S A. 1962 Mar 15;48:379–386. [PMC free article] [PubMed]
  • McCormick GM, Moon RC. Effect of increasing doses of estrogen and progesterone on mammary carcinogenesis in the rat. Eur J Cancer. 1973 Jul;9(7):483–486. [PubMed]
  • Rajaniemi H, Sogn J, Holmes P, Källfelt B, Janson PO. Fate of receptor-bound human chorionic gonadotrophin in pseudopregnant rat ovaries perfused in vitro. Acta Endocrinol (Copenh) 1985 May;109(1):115–121. [PubMed]
  • Russo IH, Frederick J, Russo J. Hormone prevention of mammary carcinogenesis by norethynodrel-mestranol. Breast Cancer Res Treat. 1989 Oct;14(1):43–56. [PubMed]
  • Russo IH, Gimotty P, Dupuis M, Russo J. Effect of medroxyprogesterone acetate on the response of the rat mammary gland to carcinogenesis. Br J Cancer. 1989 Feb;59(2):210–216. [PMC free article] [PubMed]
  • Russo IH, Koszalka M, Russo J. Human chorionic gonadotropin and rat mammary cancer prevention. J Natl Cancer Inst. 1990 Aug 1;82(15):1286–1289. [PubMed]
  • Russo IH, Koszalka M, Russo J. Effect of human chorionic gonadotropin on mammary gland differentiation and carcinogenesis. Carcinogenesis. 1990 Oct;11(10):1849–1855. [PubMed]
  • Russo IH, Koszalka M, Gimotty PA, Russo J. Protective effect of chorionic gonadotropin on DMBA-induced mammary carcinogenesis. Br J Cancer. 1990 Aug;62(2):243–247. [PMC free article] [PubMed]
  • Russo J. Basis of cellular autonomy in the susceptibility to carcinogenesis. Toxicol Pathol. 1983;11(2):149–166. [PubMed]
  • Russo J, Gusterson BA, Rogers AE, Russo IH, Wellings SR, van Zwieten MJ. Comparative study of human and rat mammary tumorigenesis. Lab Invest. 1990 Mar;62(3):244–278. [PubMed]
  • Russo J, Russo IH. Influence of differentiation and cell kinetics on the susceptibility of the rat mammary gland to carcinogenesis. Cancer Res. 1980 Aug;40(8 Pt 1):2677–2687. [PubMed]
  • Russo J, Russo IH. Biological and molecular bases of mammary carcinogenesis. Lab Invest. 1987 Aug;57(2):112–137. [PubMed]
  • Russo J, Tay LK, Russo IH. Differentiation of the mammary gland and susceptibility to carcinogenesis. Breast Cancer Res Treat. 1982;2(1):5–73. [PubMed]
  • Sinha DK, Pazik JE, Dao TL. Prevention of mammary carcinogenesis in rats by pregnancy: effect of full-term and interrupted pregnancy. Br J Cancer. 1988 Apr;57(4):390–394. [PMC free article] [PubMed]
  • Uilenbroek JT, Meijs-Roelofs HM, Woutersen PJ, Kramer P, van Cappellen WA, Gribling-Hegge LA, de Greef WJ. Changes in ovarian steroidogenesis in prepuberal rats induced to ovulate by low doses of human chorionic gonadotrophin. J Endocrinol. 1985 Oct;107(1):113–119. [PubMed]
  • Welsch CW. Host factors affecting the growth of carcinogen-induced rat mammary carcinomas: a review and tribute to Charles Brenton Huggins. Cancer Res. 1985 Aug;45(8):3415–3443. [PubMed]

Articles from British Journal of Cancer are provided here courtesy of Cancer Research UK


Save items

Related citations in PubMed

See reviews...See all...

Cited by other articles in PMC

See all...


  • Compound
    PubChem chemical compound records that cite the current articles. These references are taken from those provided on submitted PubChem chemical substance records. Multiple substance records may contribute to the PubChem compound record.
  • MedGen
    Related information in MedGen
  • PubMed
    PubMed citations for these articles
  • Substance
    PubChem chemical substance records that cite the current articles. These references are taken from those provided on submitted PubChem chemical substance records.

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...