In a small new study, ovarian cancer cells were detectable on the tampons of some women with advanced stage cancer.
"This is a proof of principle study that certainly needs more work on it before we know how useful it will be," said Dr. Charles N. Landen Jr. of the University of Virginia, Department of Obstetrics and Gynecology.
But it is helpful to know that you can pick up tumour DNA in vaginal secretions, Landen told Reuters Health by phone.
Ovarian cancer is often diagnosed at a late stage, since there is no effective screening method for early-stage ovarian cancer. About 22,000 women are diagnosed with ovarian cancer in the US each year, and almost 14,300 will die, according to the American Cancer Society.
Landen and his coauthors studied eight women with advanced serous ovarian cancer, which is the most common form of ovarian cancer. Eight to 12 hours before surgery, they each inserted a commercially available tampon, which was removed in the operating room.
All eight women had TP53 DNA mutations in their tumours, which is a very common mutation for this form of cancer, the authors write.
Five of the women had intact fallopian tubes, while three had had tubal ligation surgery previously.
Of the five women who did not have their "tubes tied," three had the exact same TP53 mutations detectable from their tampon samples, according to results published in the journal Obstetrics & Gynecology.
Identifying three out of five, or 60 per cent, of cancers is not bad, but not ideal for a disease as rare as ovarian cancer, Landen said.
"It's not enough for us to have total confidence over its ultimate utility," he said.
None of the women with tubal ligation had tumour mutations in their tampon samples.
"We have no way of knowing whether or not the DNA we picked up originated in the fallopian tubes or in the abdominal cavity," but either way it does demonstrate that cancer happening elsewhere in the genital tract does affect the vaginal canal, Landen said.
A previous study found similar tumour DNA detectable by Pap smear.
This is not yet a breakthrough in detecting ovarian cancer, according to Paul Spellman, who researches the biology of cancer at Oregon Health & Science University in Portland, and was not involved in the study.
"These findings are helping researchers move toward a method for screening for ovarian cancer," said Dr. Shannon N. Westin of the Department of Gynecologic Oncology and Reproductive Medicine at the University of Texas MD Anderson Cancer Center in Houston. "This has certainly been a 'holy grail' for some time."
Westin was not involved in the new study.
"Thus far, imaging and serum tests have not been able to reliably detect ovarian cancer at an early stage," she told Reuters Health by email. "Ovarian cancer survival is significantly improved when detected at an early stage."
Five years after diagnosis with stage 1 ovarian cancer, approximately 90 per cent of women have survived, compared to approximately 35 per cent for Stage IIIc, the most commonly diagnosed stage, she said.
It is not clear if this kind of tampon screening would identify early-stage cancers of the ovaries or fallopian tubes, Landen said.
This pilot study did identify some advanced cancers, and may be more useful some day as targeted screening for women at high risk, like those with a family history of ovarian cancer or those with the BRCA mutations, especially younger women who still want to have children and don't want their ovaries removed unless absolutely necessary, he said.
Though this method of detection is a long way from actually being used to screen women for early stage ovarian cancer, it does have the advantage that it's relatively easy for women to do and doesn't involve surgery, he noted.