By: Anne Harding, LiveScience Contributing Writer
Published: 10/07/2014 05:49 PM EDT on LiveScience
Tampons could one day help doctors spot early-stage ovarian cancer in women at high risk for this deadly disease, a small new study suggests.
In the study, researchers found tumor DNA in cells trapped in ordinary tampons that were placed in the vaginas of ovarian cancer patients.
"In about 60 percent of patients who had their [fallopian] tubes still intact, we were able to pick up tumor cells, or essentially tumor DNA, in the vaginal tract," said Dr. Charles Landen, an associate professor of gynecologic oncology at the University of Virginia in Charlottesville, and one of the study researchers. (Having intact fallopian tubes is important to the findings because the tubes are the conduits that connect the ovaries with the lower parts of the reproductive system, including the uterus and the vagina.)
This detection rate was too low for the current form of the test to be used to screen women in the general population for ovarian cancer, and the supersensitive DNA testing technology the researchers employed was too expensive for widespread use, the researchers said in their study, published today (Oct. 7) in the journal of Obstetrics & Gynecology.
But the study shows that in principle, tampons could be used to detect the cancer, the researchers said. "It's an important step toward the Holy Grail, but we're certainly not there yet," Landen told Live Science.
There will be an estimated 22,000 cases of ovarian cancer diagnosed in the United States during 2014, and about 14,000 women will die of the disease this year, according to the National Institutes of Health. Ovarian cancer is usually not detected until it has advanced. [5 Things Women Should Know About Ovarian Cancer]
Landen and his colleagues at Johns Hopkins University in Baltimore wanted to investigate whether it might be possible to identify tumor cells that had migrated from the ovary to the vagina. So, for their study, they enrolled women who were about to undergo surgery for a pelvic mass.
Of the 33 patients in the study, eight had advanced serous ovarian cancer, the most common form of the disease. But three of these women had previously had their tubes tied, meaning there would be no way for a cancer cell in the ovary to travel down to the vagina.
In three of the five women who had intact fallopian tubes, the researchers found cells in the tampon with the exact same mutation, called a TP53 mutation, that they had found in the tumor itself — a sign that the cancer cells do, indeed, move from the upper parts of the reproductive tract into the vagina.
To spot the mutations in the cells within the tampons, the researchers used a type of DNA sequencing called deep sequencing, which is able to detect tiny fractions of mutated DNA in a sample. On average, mutated DNA made up just 0.05 percent of the total sample, Landen said.
"That's the real power of the technology, but [the test] still needs to be a little bit better," said Landen, who was at the University of Alabama at Birmingham at the time of the study. "What we need to do is pick up early-stage or even precancerous lesions, before it becomes malignant."
The next step in the research will be to repeat the experiment in a larger group of women with ovarian masses, including some with early-stage ovarian cancer, Landen said. Meanwhile, his colleagues at Johns Hopkins are "tinkering" with the DNA test to see if it can be made more sensitive.
Previous attempts to develop screening tests for ovarian cancer haven't worked because they are not sensitive enough to detect the cancer in large groups of women, Landen said. "That's why a lot of the screening tests have failed — even though they're pretty good, they're not quite good enough."