American Association for Cancer Research
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Supplementary table 2 from Cancer Risk in Women Treated with Fertility Drugs According to Parity Status—A Registry-based Cohort Study

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journal contribution
posted on 2023-03-31, 14:05 authored by Marte Myhre Reigstad, Ritsa Storeng, Tor Åge Myklebust, Nan Birgitte Oldereid, Anne Katerine Omland, Trude Eid Robsahm, Louise Annette Brinton, Siri Vangen, Kari Furu, Inger Kristin Larsen

Supplementary Table 2. Hazard ratios* (HR) and 95% confidence intervals (CI) of cancer in women receiving ART as registered in the Norwegian Prescription Database, stratified by number of cycles of ART.


Oslo University Hospital



Background: Long-term safety of assisted reproductive techniques (ART) is of interest as their use is increasing. Cancer risk is known to be affected by parity. This study examined the risk of cancer after fertility treatment, stratified by women's parity.Methods: Data were obtained from all women (n = 1,353,724) born in Norway between 1960 and 1996. Drug exposure data (2004–2014) were obtained from the Norwegian Prescription Database (drugs used in ART and clomiphene citrate). The Medical Birth Registry of Norway provided parity status. HRs were calculated for all site cancer, breast, cervical, endometrial, ovarian, colorectal, central nervous system, thyroid cancer, and malignant melanoma.Results: In 12,354,392 person-years of follow-up, 20,128 women were diagnosed with cancer. All-site cancer risk was 1.14 [95% confidence interval (95% CI), 1.03–1.26] and 1.10 (95% CI, 0.98–1.23) after clomiphene citrate and ART exposure, respectively. For ovarian cancer, a stronger association was observed for both exposures in nulliparous (HR, 2.49; 95% CI, 1.30–4.78; and HR, 1.62; 95% CI, 0.78–3.35) versus parous women (HR, 1.37; 95% CI, 0.64–2.96; and HR, 0.87; 95% CI, 0.33–2.27). Elevated risk of endometrial cancers was observed for clomiphene citrate exposure in nulliparous women (HR, 4.49; 95% CI, 2.66–7.60 vs. HR, 1.52; 95% CI, 0.67–3.42). Risk was elevated for breast cancer in parous women exposed to clomiphene citrate (HR, 1.26; 95% CI, 1.03–1.54) for thyroid cancer and among nulliparous women after ART treatment (HR, 2.19; 95% CI, 1.08–4.44).Conclusions: Clomiphene citrate appears associated with increased risk of ovarian and endometrial cancer. Elevations in risks of breast and thyroid cancer were less consistent across type of drug exposure and parity.Impact: Continued monitoring of fertility treatments is warranted. Cancer Epidemiol Biomarkers Prev; 26(6); 953–62. ©2017 AACR.