Pap Smears Could One Day Detect Breast and Ovarian Cancers, Too

Mammograms are the gold standard for detecting breast cancer, but recent research suggests other screenings could one day simultaneously detect breast and other types of cancers.

In one study, researchers found that cells collected in pap smears—a routine procedure to test for cervical cancer—may also detect ovarian cancer. In a second study used, the researchers used those cervical cells to predict an individual’s risk of developing breast cancer in the future. Both studies were published in Nature Communications.

Having one test to screen for multiple cancers could potentially help detect some of the one-in-eight breast cancer cases that go undetected during mammography.

“There’s a high rate of missed cancers because of breast density,” Jack Jacoub, MD, a medical oncologist and medical director of MemorialCare Cancer Institute at Orange Coast Medical Center, told Verywell. “Breast density is more common among younger and hormonal women, and the density is lost over time as women get older allowing for breast mammography to be more sensitive to cancers.”

Simplifying the number of cancer screenings a person needs to get each year could also encourage people to seek medical care. It would make screenings more convenient for low-income communities that may not have the resources to take off work and travel to multiple appointments.

And the need to screen is more pressing than ever with many delaying care due to the COVID-19 pandemic.

“The pandemic affected a lot of screening, which were considered in many people’s views as optional because of the risks it created in accessing the healthcare system during a crisis,” Jacoub explained. “That delay is likely going to show an upswing in cancer diagnoses in the future, advanced-stage cancers, and cancers that we would have caught at an earlier stage but are now a little more far along.”

Screening For Current and Future Cancers

The first study analyzed the genetic information of cervical cells from the pap smears of people with and without ovarian cancer.

They were able to identify a high percentage of people with ovarian cancer. The cells also helped identify other types of cancer, including breast and endometrial cancer as well as people who carry a BRCA1 mutation—which puts them at a greater risk.

In a second study, the researchers studied the cervical DNA of people with and without breast cancer to construct a mathematical model that would calculate the risk of future breast cancer. The model predicted that these specific DNA signatures could find 70% to 75% of all ovarian and breast cancers. Additionally, people in the top quartile of the model had a 15.7-fold higher risk of developing breast cancer.

The idea of observing epigenetic changes in cervical cells to predict multiple hormonally sensitive cancers is interesting, Jacoub said.

However, he argues that pap smears and algorithms have a long way to go before reaching the clinic. To move the needle, a larger study involving multiple countries is needed to confirm these current findings. Then, researchers will still need to design a blood test that is inexpensive and more accessible than conventional screening methods.

“There’s a large gap of research [the study authors] need to fill, but it is interesting because the concept of cells abnormalities reflecting cancer risk doesn’t have to stop at breast cancer,” Jacoub says. “If we can sample a cell, whether it’s in the blood, tissue, or an easily swabbed area like the cervix or mouth, and somehow prove the causes that lead to these changes in the genes produce certain cancers, well, it might lead to a new direction for the future of cancer care.”

Are Other Screening Alternatives on the Horizon?

Pap smears are not the only method being studied as a potential test for multiple cancers.

For example, some blood tests can discover cancer risk and diagnosis simultaneously. One example is the CA125 blood test that measures the amount of cancer antigen 125 protein in the blood to signify ovarian or endometrial cancer.

Jacoub emphasized that blood tests are a more practical tool than pap smears to predict multiple cancer risks.

“This data is relatively early, and some of the biomarker and blood-based testing is a little bit further along, and some are commercially available right now,” Jacoub added.

Another potential but unconventional method for screening for breast cancer is testing a person’s breast milk.

A recent study found breast milk samples contain live breast cells, previously thought to contain only dead or dying cells. Since the density of breast tissues is greater while breastfeeding, mammograms have a more challenging time picking up potential signs of breast cancer unless you pump immediately beforehand. This discovery may give researchers a noninvasive approach to check for abnormalities that could indicate breast cancer.