Regular screening for ovarian cancer is not the norm. The American Cancer Society's official stance is that there are "no good tests for finding ovarian cancer early." And other experts point to a lack of evidence that screening can save lives.
But a new study published in the medical journal Lancet found that screening all women -- as opposed to just those with heightened risk -- could reduce ovarian cancer deaths by as much as 20 percent over a 14 year period. To put that in perspective, screening is nearly as successful at preventing ovarian cancer deaths as mammograms, which are recommended for all women and have been shown to prevent breast cancer deaths.
"The findings are of importance given the limited progress in treatment outcomes for ovarian cancer over the last 30 years," said Usha Menon, one of the lead researchers of the trial and a professor at the Institute for Women’s Health at University College London.
Currently, women with an above average risk of ovarian cancer -- such as those who have struggled with infertility or have a family history of breast or ovarian cancer -- are encouraged to consider one of two tests for ovarian cancer: a blood test that looks for the protein CA-125 (a protein produced by advanced ovarian tumors) or a transvaginal ultrasound, which is used to detect tumors by sight.
In the Lancet experiment, the researchers used those tools on women with no heightened risk. Their study, one of the largest ever conducted, included more than 200,000 women in the U.K. who were recruited between 2001 to 2005.
Researchers split them into three groups: Half of the participants received no ovarian cancer screening. The other half of participants was split in two groups. The first group underwent both blood and transvaginal screening, while the second did just the transvaginal test. The study lasted until 2011, with follow ups through 2014. The average woman had an 11-year follow up.
After controlling for the women in the trial who started off with undiagnosed ovarian cancer, women who were screened with both methods were 20 percent less likely to die of ovarian cancer as compared to the unscreened control group. The researchers also calculated that 641 women had to be screened with both methods in order to prevent one death by ovarian cancer over 14 years.
By comparison, 1,000 women need to have a biannual mammography screening for 20 years in order to save two or three lives from breast cancer deaths.
Of course, there are also drawbacks to any screening program. For every 10,000 women screened with both the blood test and ultrasound, 14 received false-positive diagnoses that led to surgery. Of these women, 3.1 percent had a major post-surgery complication. Among women screened with just the transvaginal ultrasound, these false-positive surgeries were even more common: For every 10,000 screens, 50 women went through surgeries for growths that were not cancerous. They had post-surgery complications at a rate of 3.5 percent.
In an op-ed published alongside the study, Prof. René Verheijen and Dr. Ronald Zweemer of the UMC Utrecht Cancer Center in the Netherlands pointed out that a lot more needs to be confirmed before a woman of average risk should go through yearly screenings.
About 21,000 women in the U.S. were diagnosed with ovarian cancer this year, and an estimated 14,000 American women died of the disease, according to the American Cancer Society. When ovarian cancer is found in the early stages, the five year survival rate is 92 percent.
Unfortunately, by the time most women with ovarian cancers are first diagnosed, the cancer has already grown and metastasized, leaving them with a much lower survival rate. Overall, the five-year survival rate for all women with ovarian cancer is just 45 percent, making it the fifth-deadliest cancer for women.
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