Infertility Articles

BACKGROUND

This study was conducted to address concerns that the use of fertility drugs with IVF (and related treatments such as GIFT) might be associated with an increased risk of cancer. Fertility drugs are used in IVF to stimulate the production of multiple eggs.

The study’s aims were:

	to see whether women who had been in an IVF program had a higher incidence of cancer than women of the same age in the general population
	to see whether the incidence of cancer was higher in women who had received fertility drugs in the course of their IVF treatment than in women who had not

STUDY DESIGN

The study followed-up 10,358 women who registered with Monash IVF between 1978 and 1992:

	5,564 women who were exposed to fertility drugs with their IVF treatment (exposed group)
	4,794 women who were referred for IVF treatment but were untreated or who had natural cycle treatment without fertility drugs (unexposed group).

Duration of follow-up ranged from 1 to 15 years. Cases of cancer that had arisen up to December 1993 were determined from cancer registries.

The observed number of cancer cases was compared with the expected number. The expected number of cases was calculated based on the incidence of cancer in women of the same age in the general population, and the number of years of follow-up for each woman in the study.

FINDINGS

	The major finding was that women who had been in the Monash IVF program did not have an increased incidence of breast cancer. (Exposed group: 16 cases observed, 18 expected. Unexposed group: 18 cases observed, 18 expected). Exposure to fertility drugs was not associated with an increased breast cancer risk.
	The incidence of ovarian cancer was not significantly increased. (Exposed group: 3 cases observed, 2 expected. Unexposed group: 3 cases observed, 2 expected).
	Women in the program had a significantly higher incidence of uterine cancer, whether or not they were exposed to fertility drugs with IVF, than the general population. (Exposed and unexposed groups combined: 5 cases observed, 2 expected.)
	Women with unexplained infertility had a significantly higher incidence of ovarian and uterine cancer, whether or not they were exposed to fertility drugs, than the general population. (Unexplained infertility: 5 ovarian cancers observed, 1 expected; 5 uterine cancers observed, fewer than 1 expected). As well as having a higher incidence of ovarian and uterine cancer than the general population, women with unexplained infertility had an increased risk of these cancers compared with women with known causes of infertility.
	There was no evidence of an increased risk of any other cancer.

CONCLUSIONS

The results from this study show that, to date, IVF treatment with fertility drugs does not appear to be associated with an increased incidence of breast cancer.

Women in the Monash IVF program, irrespective of whether they received IVF treatment, did have a higher incidence of uterine cancer than the general population. Women with unexplained infertility had a higher incidence of ovarian and uterine cancer.

These findings are based on a small number of cases and await confirmation and more detailed study in future research. Ovarian and uterine cancers are known to be more common in women who have not had children.

This work was supported by grants from the Commonwealth Department of Human Services and Health, the Fertility Society of Australia, Monash IVF, Melbourne IVF and IVF Friends.

CURRENT STUDIES

As very few women have been followed up for more than 10 years, longer-term studies of cancer incidence after infertility and IVF are necessary.

The researchers, in conjunction with the Fertility Society of Australia and IVF clinics around Australia, are conducting another similar study of 30,000 women who have been in IVF programs. The study of a larger group of women will provide further information on the risk of ovarian and uterine cancer. Findings from this study are expected in late 1998.

CANCER IN WOMEN The lifetime risk of breast cancer is 1 in 14 women. For ovarian cancer it is 1 in 94 women and for uterine cancer, 1 in 77 women. Breast cancer is the most common cancer in Australian women. The graph shows how the incidence of these cancers increases with age, shown as the number of new diagnoses of cancer per 100,000 women per year.

FURTHER READING

Venn A, Watson L, Lumley J, Giles G, King C, Healy D.
Breast and ovarian cancer incidence after infertility and in vitro fertilisation.
Lancet 1995; 345: 995-1000.

National Health & Medical Research Council (Australia).
Long-term effects on women from assisted conception.
NHMRC 1995. (Available from Commonwealth Government bookshops.)

MORE INFORMATION

For more information about the study, please contact:

Ms Fiona Bruinsma or Dr Alison Venn,
Centre for the Study of Mothers’ & Children’s Health,
La Trobe University,
463 Cardigan St,
Carlton, Vic 3053.
Tel: (03) 9348 1211

or

Prof David Healy,
Monash IVF,
Tel: (03) 9429 9188

or your IVF specialist.

Also, you may like to visit the M&C Homepage:
Centre for the Study of Mothers' & Children's Health.