Overall cancer incidence is similar between women who have used medically assisted reproduction and the general population, but certain cancers may occur at slightly higher rates, according to an Australian population–based cohort study published in JAMA Network Open by Vajdic et al.
The investigators continued, “this evidence should enhance awareness, cancer risk behavior modification (reduce adiposity, sun exposure, smoking), and clinical guidelines for follow-up care.”
Inside the Analysis
Investigators ascertained medically assisted reproduction treatments, pregnancies, incident cancers, and deaths through linkage of population-based administrative health data sets with statutory registries. The analysis included women aged 18 to 55 years who used medically assisted reproduction between 1991 and 2018.
A total of 417,984 women exposed to medically assisted reproduction were included in the study. Of this population, 274,676 (65.7%) had used assisted reproductive therapy (median age = 34 years; median follow-up = 9.42 years). Additionally, 120,739 women (28.9%) had used intrauterine insemination with ovulation stimulation (median age = 34 years; median follow-up = 11.67 years), and 175,510 (42.0%) had undergone ovulation induction using clomiphene citrate (median age = 32 years; median follow-up = 9.42 years).
Cancer incidence among medically assisted reproduction–exposed women was compared with a matched general population (by age, jurisdiction, and calendar year), with cancer standardized incidence ratios (SIRs) and rate differences as the main outcomes.
Cancer Incidence Findings
The overall incidence of invasive cancer was reported to be comparable with the general population in women who underwent assisted reproductive therapy (SIR = 1.00, 95% confidence interval [CI] = 0.98–1.02) and intrauterine insemination with ovarian stimulation (SIR = 0.99, 95% CI = 0.97–1.02) but slightly elevated in those who received clomiphene citrate (SIR = 1.04, 95% CI = 1.00–1.07).
Across all cohorts, the incidence of uterine cancer (SIRs = 1.23–1.83) as well as both in situ and invasive melanoma (SIRs = 1.07–1.15) was increased, whereas the incidence of cervical cancer (SIRs = 0.52–0.61) and cancers of the trachea, bronchus, and lung (SIRs = 0.62–0.70) was reduced.
Ovarian cancer incidence was elevated in women who underwent assisted reproductive therapy (SIR = 1.23, 95% CI = 1.10–1.37) and intrauterine insemination with ovarian stimulation (SIR = 1.18, 95% CI = 1.01–1.37). The incidence of in situ breast cancer was increased only after assisted reproductive therapy (SIR = 1.24, 95% CI = 1.12–1.38), whereas the incidence of invasive breast cancer was not found to be elevated in any cohort.
The investigators reported that rate differences for invasive cancers with elevated incidence were small, ranging from fewer than 1 to 6.51 cases per 100,000 person-years.
They concluded, “In this cohort study of cancer incidence in women who received medically assisted reproduction, the overall incidence of cancer was comparable with that of the general population. The incidence of certain cancers appeared elevated; however, the excess numbers of these cancers were small, and there was reduced incidence of other cancers. Causation cannot be inferred from this descriptive evidence, but findings may guide women and their health-care practitioners.”
Claire Melissa Vajdic, PhD, of the University of New South Wales, Sydney, is the corresponding author of the article in JAMA Network Open.
DISCLOSURE: The study was funded by a grant from the National Health and Medical Research Council. For full disclosures of the study authors, visit jamanetwork.com.
