Fertility drugs may increase the risk of breast cancer among women who successfully conceived. It was not so pronounced in those who didn't get pregnant after the treatment, a new study says.
The link between fertility drugs and breast cancer has been an interest of study from a long time. Ovulation-stimulating fertility drugs are commonly known to increase estrogen levels in women, which further leads to the cancer risk.
Researchers from the National Institute of Health, in their effort to examine the link between fertility drugs and breast cancer included pair of sisters- 1,400 breast cancer patients (diagnosed before the age 50) and their sisters (1,600) without breast cancer.
Among the participants, 288 reported using ovulation-stimulating fertility drugs clomiphene citrate and follicle-stimulating hormone and about 141 women reported getting pregnant at 10 weeks or after starting the medication.
Dr. Chunyuan and team found that women who used fertility drugs and conceived at 10 weeks or more to have an increased risk of developing breast cancer before turning 50 than the women who didn't conceive after following the medication. According to the investigators, the fertility drugs exposure added by remodelling of breast tissue related to pregnancy may have led to the occurrence.
"Our data suggest that exposure to a stimulated pregnancy is enough to undo the reduction in risk associated with a history of exposure to ovulation-stimulating drugs," the authors wrote, in a statement.
But, experts, welcoming the findings urge women not to shy away from fertility drugs due to fears of cancer risk.
"Even in the group at an increased risk after their pregnancy, their risk was not higher than the general public," Cedars, who was not involved in the study told ABC News. "If you use fertility drugs, you're not increasing your risk."
The findings of the study are published in the Journal of The National Cancer Institute.
The current study supports a previous study published in June that found young women who underwent fertility treatment at the age of 24 at a higher risk of developing breast cancer than others who adopted the treatment by the age of 40. Apart from IVF treatment, earlier studies have highlighted other factors, including the lifestyle of women that leads to increase cancer risks.
A study published in the Journal Occupational and Environmental Medicine examined the link between night shifts and breast cancer and found women working night shifts at a 40 percent higher risk of developing breast cancer than others. The main reason behind this occurrence was the continuous exposure to light at night which reduces the production of melatonin, a night hormone that protects the body against certain cancers.
