New York, Nov 13 (IANS): It's better to ignore simple ovarian cysts as researchers have found that such cysts are extremely common in women and do not require additional ultrasound surveillance or surgical removal.

Simple cysts are common in both pre- and post-menopausal women, and are not linked to a higher risk of ovarian cancer, showed the findings published in the journal JAMA Internal Medicine.

As a result, unless they are symptomatic, simple cysts can be safely ignored, the researchers found.

By contrast, complex cysts or solid ovarian masses are far less common, but are associated with a significantly higher risk of developing malignant cancer. These masses need to be followed or surgically removed, said the study.

"Our study found that asymptomatic simple cysts of any size should be considered normal findings in women of any age and ignored," said corresponding author Rebecca Smith-Bindman, Professor University of California, San Francisco (UCSF) in the US.

"There's a great deal of unnecessary medical surveillance that goes on for simple cysts," she said.

The researchers tracked 72,093 women who underwent pelvic ultrasound between January 1997 and December 2008. Approximately 75 per cent of them were less than 50 years old.

During the study period, the women underwent 118,778 pelvic ultrasound exams. Among the 54,452 women under 50, the researchers estimated that approximately 24 per cent (12,957 women) were diagnosed with a simple cyst and none developed cancer during follow-up.

Among the 17,641 women aged 50 and older, approximately 13 per cent (2,349 women) were diagnosed with a simple cyst and only one was diagnosed with cancer.

In the statistical analysis, the risk of developing cancer was approximately zero in women with a simple cyst, regardless of the size of the cyst.

The study identified 210 cases of ovarian cancer, nearly all of which were seen in women with complex cystic mass.

Ultrasound accurately predicted the probability of cancer, for which the odds significantly rose in women with complex cystic or solid ovarian masses, the authors said.

They estimated that 6.5 per cent of post-menopausal women with such masses will be diagnosed with ovarian cancer within three years.

By contrast, women with simple ovarian cysts were not associated with a higher risk of cancer than those with normal ovaries.