No. Simple ovarian cysts — fluid-filled sacs on the ovaries — are normal, extremely common in both pre-and post-menopausal women, and aren’t linked to a higher risk of ovarian cancer. They also do not require additional ultrasound surveillance or surgical removal.

“Simple cysts are almost universally benign, but because of concern that they could harbor a cancer precursor, they have resulted in frequent surveillance and referrals to gynecologists and oncologists,” said corresponding author Dr. Rebecca Smith-Bindman, a professor in the department of radiology and biomedical imaging at the University of California, San Francisco.

There’s little evidence that concern is warranted, however: Smith-Bindman and researchers from UCSF and the American health care provider Kaiser Permante observed more than 72,000 women and conducted close to 11,900 pelvic ultrasound exams over a dozen years. Among the 54,452 women under age 50 in the study, one-quarter were diagnosed with a simple cyst — none of whom developed cancer. Among the remaining women in the study, those aged 50 and older, 13% had a simple cyst; only one of these woman was diagnosed with cancer.

Researchers therefore concluded, based on statistics, that the risk of developing cancer was approximately zero in women with a simple cyst, regardless of the size of the cyst.

“Our study found that asymptomatic simple cysts of any size should be considered normal findings in women of any age, and ignored,” said Smith-Bindman.

The study authors say their findings should encourage health care providers to move away from the widespread practice of monitoring simple ovarian cysts.

Complex ovarian cysts, on the other hand, are a different story. These contain either blood or solid substance and need treatment. Among the whole cohort of 72,000 women, there were 210 cases of ovarian cancer — nearly every woman in this group had a complex ovarian cyst.

“Ovarian cancer is a devastating disease. But ovarian cancer does not arise in simple cysts and following simple cysts with imaging will not result in improved early detection of ovarian cancer,” Smith-Bindman said.