TWU virus research key to cancer link

You’ve probably never heard of cytomegalovirus, but there’s a good chance you or someone you know has it. It’s estimated nearly half of Americans have the virus, known as CMV, but there’s a very good chance you’ll never know you have it.

For most people with a healthy immune system, CMV has no symptoms. It doesn’t sicken or kill. Doctors rarely treat it or even screen for it, and CMV is unlikely to impact your health.

Unless you have breast cancer.

Doctors and researchers do not believe CMV – which is transmitted through saliva, blood, and breast milk – causes cancer or makes someone more likely to get cancer. But it’s possible that the virus affects breast cancer itself, making it more difficult to treat.

Texas Woman’s University biology PhD student Erica Garcia is researching the relationship between CMV and cancer. Understanding it may be key to better treatment of breast cancer and possibly other cancers.

"CMV is an indicator of treatment resistance,” Garcia said. “It’s actually more prevalent in breast-tumor tissue than in adjacent normal tissue, so that suggests maybe it plays a role in altering the invasive characteristics of breast cancer.”

Cancer cell receptors are the most common, well-established targets for treating cancer, so anything that disrupts receptors can disrupt treatment. Garcia is examining how CMV affects immune receptors and may enable the cancer cell to avoid detection by the immune system.

There are other long-understood consequences of CMV. The virus in pregnant women can cause birth defects, and it can cause problems for those receiving organ transplants.

But the notion that CMV impacts cancer cells and how they respond to treatment is new.

The first clues that inspired this medical detective work came to Garcia during her job at a genetic testing lab.

“My job was to double-check the data and patient clinical notes for people who are getting checked for genetic mutation that could make them more vulnerable to cancer,” she said.

“A lot of the work so far has been in biopsy samples, which are fixed,” Garcia added. “While that’s a good starting point, it leaves the question of whether CMV is the causative factor. It’s important to establish if CMV is causing this, because there are some complicated interactions that go on in your body.”

Garcia’s early findings are that CMV alters the cancer cells’ hormone receptor status, degrading the effectiveness of cancer treatment.

The scientific community so far has reacted skeptically to the concept of CMV’s impact on cancer.

“It’s a matter of getting the medical community to see that this is important,” Spencer said. “We have separate data of human specimens that clearly show that people who have CMV have different immune responses to cancer than people who don’t. If we can explain the underlying mechanism of how this is happening, we could get a little more buy-in of our ideas.”

Garcia’s research could help persuade the community, and therefore lead to changes in the treatment of breast cancer. For starters, screening breast-cancer patients for CMV, especially when initially diagnosed.

“If physicians check that CMV status, it might help them prescribe a better treatment,” Garcia said. “The goals of the virus and the cancer cells are the same. Both want the cell to survive long enough to produce more virus or cancer. I want to look at those immune receptors to see how CMV is helping the cancer cells hide from your immune system.”

One bit of good news in this unfolding mystery: while CMV cannot be eradicated, it can be controlled with available antiviral medication.

“If it’s something very specific where the virus is causing these receptors to be degraded, that could be a relatively quick intervention,” Spencer said.

It can’t come fast enough for the estimated 287,000 women who will be diagnosed with breast cancer this year, according to the American Cancer Society, accounting for 30% of cancers among women. It’s estimated that one in eight women in the United States will develop breast cancer.

"The thought that I could improve those lives is a big motivation," Garcia said.

And improved treatment could mean increased chances of survival, more fine-tuned treatment, shortened treatment and fewer side effects. By virtually any measure, it’s ground-breaking research that could have far-reaching implications.

“This is happening at TWU,” Spencer said. “This is cutting-edge research that has the potential to change the treatment for some women with breast cancer.”