The Pap smear, long the standard test for cancer of the cervix - the muscular opening of the uterus - is becoming a one-stop check-up for multiple cancers. Researchers have developed a combination Pap test that also screens for two other hard-to-spot and potentially deadly gynecological tumors.
Scientists at Johns Hopkins University in Baltimore, Maryland, have developed a test that piggybacks on the widely used Papanicolaou or Pap smear test for cervical cancer, expanding it to also look for the genetic abnormalities associated with ovarian cancer and cancer of the endometrium, the lining of the uterus. In the United States, these two cancers are diagnosed in about 70,000 women every year, and the tumors kill about one third of them.
There currently are no screening tests for the two cancers. But researchers found that abnormal DNA is shed from endometrial and ovarian tumors and can be detected among healthy cells in fluid extracted from the cervix.
Using genome-wide association studies, the Hopkins researchers identified 12 of the most common mutated genes in both cancers, incorporating a way to recognize them into the routine Pap smear.
Their new PapGene test was used to screen cervical cell samples from 24 women with endometrial cancer, detecting the disease with 100 percent accuracy. However, study co-author Isaac Kinde at Johns Hopkins' Sidney Kimmel Comprehensive Cancer Center, said PapGene picked up only nine of 22 ovarian cancers in patients with the disease, a relatively low accuracy rate of just 41 percent.
Kinde said ovarian cancer may be harder to detect than endometrial cancer because of where the ovaries are located.
“I think the most likely explanation for the result that we got is the fact that a cancer cell has to travel farther away from the ovaries to get to the cervix,” he said.
Kinde said researchers are working to make PapGene more sensitive in the detection of ovarian cancer. He said he would like to see a time when a simple Pap test is routinely used to screen for all three types of gynecologic cancer.
“That’s been the dream from the very beginning. You know that is the goal. From the perspective of the patient and from the gynecologist, nothing changes for them," he said. "It’s a routine Pap smear and it’s essentially just another box to check if you want to look for endometrial and ovarian cancers.”
An article on the development of the PapGene test for cervical, endometrial and ovarian cancer - by researchers at Johns Hopkins University, Memorial Sloan-Kettering Cancer Center in New York, and the University of Sao Paolo in Brazil - is published in the journal
Science Translational Medicine.