The most common sexually transmitted disease can double a woman’s risk of ovarian cancer, according to a new study published Thursday.
Women suffering from chronic chlamydia infections twice had the risk of developing ovarian cancer as women without evidence of infection, researchers are expected to report in April at a meeting of the American Association for Cancer Research.
Ovarian cancer is not common, but it has been diagnosed this year in more than 21,000 American women and will kill more than 14,000. It is the fifth leading cause of death from women in cancer and kills 55 percent of patients within five years.
Chlamydia are very common. More than 1.5 million Americans have chlamydia, according to the Centers for Disease Control and Prevention. Chlamydiae can be easily treated with antibiotics, but they often cause no symptoms, so people can and do not get infected for several months or even years.
Over time, chlamydia causes widespread inflammation that causes infertility. This new study suggests that it can also cause cancer.
The team did not analyze gonorrhea, another extremely common sexually transmitted infection that also causes pelvic inflammation.
Doubling the risk does not significantly increase the number of cases, but there are not many known reasons besides genetics.
The simplest known risk factor is a family history of ovarian cancer. However, most cases are found in women with no known family history of ovarian cancer. Women with endometriosis – an overgrowth of the endometrium – have an increased risk of ovarian cancer.