It's a common gynaecological finding: A growth on an ovary, which turns out to be a benign cyst. Is surgical removal necessary?
Not always, according to data from a new study of more than 1 900 such cases in which outcomes were tracked for two years post-diagnosis.
The team behind the research now believes that most women with non-cancerous ovarian cysts can simply be monitored over time, instead of having invasive surgery to remove the growths.
"Our results may lead to a paradigm shift, resulting in less surgery for non-cancerous ovarian cysts — on condition that trained ultrasound examiners reliably exclude cancer," said co-lead researcher Tom Bourne. He's a professor at Imperial College London in the United Kingdom.
As described by the researchers, ovarian cysts are fluid-filled sacs that develop on ovaries and are identified through ultrasound scans. They're common and usually don't cause any symptoms, but in some cases do result in pelvic pain and bloating.
Cysts can be non-cancerous (benign) or cancerous, and should always be removed if suspected to be cancerous. However, even when a cyst is benign, doctors often recommend removal due to concerns about serious complications, such as the cyst bursting or causing the ovaries to twist. There's also the possibility that a benign cyst might turn cancerous, or that it was initially misidentified as benign.
But surgery comes with risks and complications of its own. And so with benign cysts, doctors sometimes instead turn to "watchful waiting" — conducting scheduled ultrasound scans to monitor cyst size and appearance. Many ovarian cysts will go away over time or do not change.
However, watchful waiting is controversial and some physicians believe benign cysts should always be removed.
Misdiagnosed as benign
In an attempt to decide the issue, Bourne and his colleagues tracked two-year outcomes for 1 919 women, average age 48, in 10 countries. All of the women underwent monitoring scans for two years after being diagnosed with benign cysts. The average cyst size was four centimetres.
In one in five cases, the cysts simply disappeared on their own, according to the report published in The Lancet Oncology. In another 16% of cases, women eventually went on to have cyst-removing surgery.
But, overall, in 80% of the cases, either the cyst disappeared or did not require surgery, the investigators found.
Only a very small number — 12 women, or just 0.4% — were later diagnosed with ovarian cancer. These cases may have been due to the cysts being misdiagnosed as benign on the initial ultrasound scan, rather than a benign cyst turning cancerous, the researchers said.
The rate of ovarian twisting or cyst rupture was also very small — 0.4% and 0.2%, respectively.
Based on these findings, the risks of watchful waiting have to be balanced against the risks of surgical complications, the study authors concluded. The risk of surgical complications — such as bowel perforation — among women aged 50 to 74 is between 3% and 15%, they noted.
Erring on the side of caution
Study co-lead author Dirk Timmerman said, "Despite these surgical risks being small, if the women in this age group underwent surgery in our study, then we could speculate that 29 to 123 of them could have suffered severe surgical complications." Timmerman is a professor at KU Leuven in the Netherlands.
"Instead, only 96 of them underwent surgery, which means severe complications may have been avoided in between 29 to 123 women," he explained in an Imperial College London news release.
One US expert agreed that the issue of how to deal with benign cysts has been a difficult one, with most doctors erring on the side of caution.
"Though opinion is divided, the majority of surgeons around the world believe benign ovarian cysts should be surgically removed," said Dr Mitchell Kramer. He directs obstetrics and gynaecology at Northwell Health's Huntington Hospital in Huntington, New York.
However, the new data "suggest the benefit of watchful waiting without surgery," Kramer added. "Certainly, further study is advisable and each case should be managed individually. However, there is evidence to support this alternative management in the appropriate patient and setting."
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