Incidence of cancer among women using long versus monthly cycle hormonal replacement therapy, Finland 1994–1997 (original) (raw)

Abstract

Objective: This study was initiated as a consequence of a clinical observation in one hospital of several endometrial carcinomas among users of a fixed combination of a 3-month cycle oral hormonal replacement therapy (HRT), which has been marketed in Finland since 1990. We studied whether the use of 3-month (“long”) cycle HRT is accompanied by a higher risk of endometrial cancer than the use of monthly cycle HRT.

Methods: A nationwide cohort of 15,956 long cycle and 78,549 monthly cycle HRT users since January 1994 was extracted from the files of the national medical reimbursement register and followed up for cancer incidence through the Finnish Cancer Registry up to the end of 1997.

Results: There were 61 cases of endometrial cancer among long cycle HRT users which significantly exceeds the average incidence in the Finnish population (standardized incidence ratio (SIRlong) 2.0, 95% confidence interval (CI) 1.6–2.6). The SIR among users of monthly cycle HRT products (SIRmonthly) was 1.3 (1.1–1.6) and the ratio SIRlong/SIRmonthly thus 1.5 (95% CI 1.1–2.1). Endometrial cancers among long cycle HRT users occur more often in early stages than in the general population and are more often highly differentiated. A survey of a sample of endometrial cancer patients in the long cycle HRT group revealed that all of them also had a history of other HRT. Users of both long and monthly cycle HRT had a similar statistically significant 30% excess of breast cancer in comparison to national incidence rates, while the incidence of colon cancer was decreased in both groups. There was no difference between the HRT groups in overall cancer morbidity.

Conclusions: Our results imply that all HRT users have an increased risk of endometrial cancer, and long cycle HRT carries a higher relative risk than monthly cycle HRT. However, in this non-randomized setting it is impossible to judge whether this excess is attributable to the type of HRT or to patient selection. In-depth studies are needed to find out possible dose–response associations and to evaluate the role of potential confounders in detail.

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References

  1. International Agency for Research on Cancer (1999) Monographs on the Evaluation of Carcinogenic Risks to Humans, vol. 72: Hormonal Contraception and Post-menopausal Hormonal Therapy. Lyon: IARC.
    Google Scholar
  2. Grady D, Gebretsadik T, Kerlikowske K, Ernster V, Petitti D (1995) Hormone replacement therapy and endometrial cancer risk: a meta-analysis. Obstet Gynecol 85: 304-313.
    Google Scholar
  3. Beresford SAA, Weiss NS, Voigt LF, McKnight B (1997) Risk of endometrial cancer in relation to use of estrogen combined with cyclic progestagen therapy in postmenopausal women. Lancet 349: 458-461.
    Google Scholar
  4. Pike M, Peters R, Cozen W, et al. (1997) Estrogen-progestin replacement therapy and endometrial cancer. J Natl Cancer Inst 89: 1110-1116.
    Google Scholar
  5. Weiderpass E, Adami H-O, Baron JA, et al. (1999) Risk of endometrial cancer following estrogen replacement with and without progestins. J Natl Cancer Inst 91 1131-1137.
    Google Scholar
  6. Collaborative Group on Hormonal Factors in Breast Cancer (1997) Breast cancer and hormone replacement therapy: collabo-rative reanalysis of data from 51 epidemiological studies of 52,705 women with breast cancer and 108,411 women without breast cancer. Lancet 350: 1047-1059.
    Google Scholar
  7. Folsom AR, Mink PJ, Sellers TA, Hong CP, Zheng W, Potter JD (1995) Hormonal replacement therapy and morbidity in a pro-spective study of postmenopausal women. Am J Public Health 85: 1128-1132.
    Google Scholar
  8. Kampman E, Potter JD, Slattery ML, Caan BJ, Edwards S (1997) Hormone replacement therapy, reproductive history, and colon cancer: a multicenter, case±control study in the United States. Cancer Causes Control 8: 146-158.
    Google Scholar
  9. Teppo L, Pukkala E, Lehtonen M (1995) Data quality and quality control of a population-based cancer registry. Experience in Finland. Acta Oncol 33: 365-369.
    Google Scholar
  10. Pukkala E (1992) Use of record linkage in small-area studies. In: Elliot P, Guzick J, English D, Stern R, eds. Geographical and Environmental Epidemiology. Oxford: Oxford University Press, pp. 125-131.
    Google Scholar
  11. Pukkala E (1995) Cancer Risk by Social Class and Occupation. A Survey of 109, 000 Cancer Cases among Finns of Working Age. Contributions to Epidemiology and Biostatistics, vol. 7. Basel: Karger.
    Google Scholar
  12. Hill HA, Austin H (1996) Nutrition and endometrial cancer. Cancer Causes Control 7: 19-32.
    Google Scholar
  13. Berg M-A, Niemensivu H, Piha T, Puska P (1990) Health Behaviour among Finnish Adult Population, Spring 1989. Publica-tions of the National Public Health Institute B 1/1990. Helsinki: Finnish Government Printing Centre.
    Google Scholar
  14. Luoto R, Hemminki E, Topo P, Uutela A, Kangas I (1992) Hysterectomy among Finnish women: prevalence and women's own opinions. Scand J Soc Med 20: 209-212.
    Google Scholar
  15. Annual Reports of the Results of Treatment in Gynecological Cancer, 1994 vol. 22. FIGO.

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Authors and Affiliations

  1. Finnish Cancer Registry, Institute for Statistical and Epidemiological Cancer Research, Liisankatu 21B, FIN-00170, Helsinki, Finland
    Eero Pukkala
  2. Felicitas Clinic, Helsinki, Finland
    Annika Tulenheimo-Silfvast
  3. Helsinki University Central Hospital, Helsinki, Finland
    Arto Leminen

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  1. Eero Pukkala
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  2. Annika Tulenheimo-Silfvast
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  3. Arto Leminen
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Pukkala, E., Tulenheimo-Silfvast, A. & Leminen, A. Incidence of cancer among women using long versus monthly cycle hormonal replacement therapy, Finland 1994–1997.Cancer Causes Control 12, 111–115 (2001). https://doi.org/10.1023/A:1008934919159

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