In a comprehensive study led by researchers from UNSW Sydney, it has been found that women undergoing fertility treatments, including in vitro fertilization (IVF), do not face a higher overall risk of invasive cancer compared to the general population. However, the study, published in JAMA Network Open, did identify slight variations in the incidence of certain specific cancers among these women.
The research analyzed the health records of over 417,000 Australian women, revealing that while some cancers were slightly more prevalent, others occurred less frequently. The findings highlight the importance of interpreting these results with caution, considering the myriad factors influencing cancer risk.
Reassuring Findings for Women Undergoing Fertility Treatments
Joint-lead author Dr. Adrian Walker, from UNSW’s Centre for Big Data Research in Health, emphasized the reassuring nature of the study’s findings. “Women who’ve had assisted fertility should continue to participate in routine cancer screening programs they’re eligible for,” he advised. “And they should discuss their cancer risk with their doctor, to understand how else they can reduce their risk.”
The study scrutinized national health and cancer records from 417,984 women who underwent medically assisted reproduction between 1991 and 2018. This encompassed IVF, intrauterine insemination, and treatments with the fertility drug clomiphene, examining cancer outcomes over an average period of 10 years.
Specific Cancer Variations Observed
The analysis revealed that uterine and ovarian cancers, along with melanoma, were slightly more common among women who had undergone IVF. Additionally, a non-invasive form of breast cancer was noted to be more prevalent, although the incidence of invasive breast cancer did not increase. Conversely, certain cancers, such as cervical and lung cancer, were less common in these women.
“It is very normal for a specific group of people to have a slightly different cancer profile from the general population,” Dr. Walker noted. “But as we see here, that doesn’t mean that their overall risk is increased.”
Understanding Relative Risk Versus Absolute Risk
Further dissecting the data, the study found that uterine cancer was between 23% and 83% more common, depending on the fertility treatment type. Ovarian cancer saw an increase of 18% to 23%, while melanoma was about 7% to 15% more common. On the flip side, cervical cancer rates were approximately 40% lower, and lung cancer rates about 30% lower than in the general population.
Across the cancers that were more common, the largest increase amounted to three to seven extra cases per 100,000 women per year.
Prof. Claire Vajdic, the study lead from UNSW’s Kirby Institute, pointed out, “Very few medical treatments are without risk, but the elevated cancer incidence here is low.”
Factors Influencing Cancer Risk
Several factors could explain why certain cancers were more prevalent among women who had fertility treatment. Prof. Vajdic explained, “Women who need fertility treatment may differ from other women in ways that affect cancer risk. Certain underlying causes of infertility, such as endometriosis and polycystic ovary syndrome, are known to increase the risk of uterine and ovarian cancers.”
The study also noted that women undergoing fertility treatment were more likely to reside in major cities and come from socioeconomically advantaged backgrounds. Although not directly examined in this study, these women are also more likely to have fair skin and less likely to smoke. Additionally, routine cancer screenings are typically up to date before commencing fertility treatments.
Dr. Walker added, “What this study does is describe cancer patterns we’re seeing at a population level. It doesn’t tell us the risk of receiving treatment, or the risk for individual women who undergo treatment.”
Future Directions and Continued Research
Given that many women in the study were still relatively young at the end of the follow-up period, the researchers suggested that longer-term studies could provide more insights. “Continued cancer awareness is important as this population ages,” Prof. Vajdic emphasized.
The researchers concluded that while the overall cancer risk post-fertility treatment is not heightened, ongoing research is essential to better understand the incidence variations for individual cancers. This knowledge will empower women and their healthcare providers to make informed decisions regarding fertility treatments and cancer risk management.
