Causal associations with ART 'unlikely'
“Women who develop cancer and have undergone ART procedures in the past may wonder whether their cancer may be caused by ART. Based on the results from our study, that seems unlikely, and that is a very reassuring message from practicing oncologists to women diagnosed with ovarian cancer. Another important message is that, in ART-treated women, increasing parity reduces the risk of ovarian cancer,” Dr. van Leeuwen said.
She added that the risk of borderline ovarian tumors did not increase in women who received multiple ART procedures, “which makes it somewhat less likely that ART would have caused their borderline ovarian tumor.”
The study does not exclude the possibility that ART might increase the risk of ovarian tumors after age 60.
“Despite our long follow-up, the age of the women at the end of our study was still relatively young [average 56 years]. Because the incidence of ovarian cancer increases with older age, it is vital to continue to follow these women. Only then can we be sure that ART does not increase the risk of ovarian tumors in the very long run,” Dr. van Leeuwen said.
“This study offers confirmation of several previous studies and provides reassurance about the risk of ovarian cancer after ART procedures,” said Daniel Kenigsberg, MD, of RMA Long Island IVF in New York. Dr. Kenigsberg was not involved in this study but has performed more than 30,000 ART procedures over the past 32 years.
“Researchers have looked at whether fertility drugs cause ovarian cancer in different ways and in different countries, and there is no cause-and-effect relationship. There was no dose-response relationship between ART and ovarian tumors in this study. It’s more likely there is something wrong with the women’s ovaries that lead to borderline tumors and infertility more than any treatment,” Dr. Kenigsberg added.
“Perhaps both fertility and cancer relate to an underlying ovarian issue, but this would not explain the increased cancer incidence in those who never attempted pregnancy, that is, women who are voluntarily childless. Pregnancy is statistically protective: more pregnancies lead to less ovarian cancer, but this is far from absolute,” he explained.
Dr. Kenigsberg suggested that oncologists should be aware of a patient’s obstetrical history and fertility history as well as any related medical interventions.
“Borderline tumors look like cancer and have histologic features of cancer but do not meet the criteria for a cancer diagnosis,” he said. “They require close surveillance because their relationship to the development of full-fledged cancer is uncertain.”
This research was supported by grants from the Dutch Cancer Society. The authors and Dr. Kenigsberg have no conflicts of interest.