Medically Assisted Reproduction Not Linked to Meaningful Increase in Cancer Risk: JAMA

A new study published in the Journal of American Medical Association showed that although certain hormone-related malignancies were linked to medically assisted reproduction, the overall rise in anticipated cancer incidence was negligible. 

Knowing if medically assisted reproductive (MAR) therapies are linked to a higher risk of hormone-related malignancies is crucial for women undergoing MAR therapy and their doctors. In order to ascertain the risk of hormone-related malignancies after MAR therapy, this study was carried out.

This cohort research employed administrative records and Australian health registries as part of an imitated target trial design. Women between the ages of 18 and 55 who were registered in Medicare, Australia's universal health insurance program, between January 1, 1991, and December 31, 2018, were among the participants.

Data from April 2024 to July 2025 were examined. Medicare records were used to characterize the following exposures: ovulation induction with clomiphene citrate, intrauterine insemination or ovarian stimulation, and assisted reproduction therapy.

396,661 of the 1,748,927 women who were identified had a history of MAR exposure. 

E-value analysis indicated that confounding resulting from underlying infertility issues might explain the observed rise for uterine, ovarian, and thyroid cancers, even though an enhanced risk of most hormone-related malignancies was noted following MAR therapy. 

Fewer than 20 more cases of invasive cancer per 100,000 women annually were expected for treated versus comparison groups. 

Increased cancer risk in the initial years following therapy was observed in emulated trials on the six hormone-related malignancies as well as pancreatic and hematological cancers, indicating detection bias. 

Following MAR therapy, there was an increased risk of hematological malignancies, suggesting that uncontrolled racial and ethnic confounding may be the cause of the reported extra risk for a number of cancers.

Overall, researchers investigated the relationships between three forms of MAR treatment—assisted reproductive technologies (ART), intrauterine insemination (IUI) or ovarian stimulation (OS), and clomiphene citrate—and hormone-related malignancies in women in this cohort research of MAR and cancer utilizing target trial emulation.

The majority of hormone-related malignancies showed elevated relative risk after MAR, while the estimated absolute excess risk only slightly rose. In several instances, bias analysis and the inclusion of negative control tumors revealed that the increased risk could be entirely due to uncontrolled confounding. Patients and clinicians should be informed that there may be a little elevated risk of cancer after receiving MAR therapy.

Source:

Walker, A. R., Venetis, C., Opdahl, S., Anazodo, A. C., Hacker, N. F., Chapman, M., Jorm, L., Norman, R. J., Stern, C., Sansom-Daly, U. M., Chambers, G. M., & Vajdic, C. M. (2026). Medically assisted reproduction and hormone-related cancers. JAMA Network Open, 9(7), e2622832. https://doi.org/10.1001/jamanetworkopen.2026.22832