Melbourne: Scientists have found that specific immune cells can actually make women more susceptible to cancer at certain stages in their menstrual cycle.
Researchers from University of Adelaide focused their efforts on immune cells known as macrophages in the breast, and how the role of these cells changes because of fluctuations in hormones during different times of the month.
The results of laboratory studies showed that while the immune cells have a role to play in the normal function of the breast, at certain stages in the menstrual cycle they may help to make the breast more susceptible to cancer.
"These cells should be protecting our body from cancer, but at certain times of the month it appears macrophages might be allowing cancerous cells to escape immune system detection," said the lead author of the study Wendy Ingman, Head of the Breast Biology & Cancer Unit with the University of Adelaide's School of Medicine, the Robinson Institute and the Queen Elizabeth Hospital.
"We think there is a window of risk that opens up around the time when women have their period. This is when levels of the hormone progesterone drop, and this affects how the breast functions," she said.
"At this time, immune defenses in the breast tissue are down and women could be more susceptible to the initiating factors that lead to breast cancer," she added.
Ingman said researchers have known for some time that there is a link between the number of years of menstrual cycling and breast cancer risk.
The study was published in the journal Biology of Reproduction.