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MONDAY, Aug. 24, 2015 (HealthDay News) -- Ovarian cancer patients who use certain blood pressure drugs often live longer than other women with the disease, researchers report in a finding that hints at a potential new treatment for the deadly cancer.
The difference was especially stark among women using older, "non-selective" beta blockers: They typically lived for almost eight years after their cancer diagnosis, versus three years among women not taking any beta blocker.
However, experts urged caution in interpreting the findings, published online Aug. 24 in the journal Cancer.
The study involved a review of patient records, which is not the type of study that can prove a treatment works. There could be other reasons that women on beta blockers lived longer with ovarian cancer.
To get direct evidence of a link, researchers need to run a clinical trial where ovarian cancer patients are randomly assigned to take a beta blocker or stick with standard treatment.
"You need to be very cautious about retrospective data like this," said senior researcher Dr. Anil Sood, of the University of Texas M.D. Anderson Cancer Center, in Houston. "We still need clinical trials."
Dr. Christina Annunziata, a researcher at the U.S. National Cancer Institute, agreed.
First, doctors need to know whether it's even safe to give beta blockers to women with ovarian cancer, said Annunziata, who co-wrote an editorial published with the study.
"If you don't have high blood pressure and you take a drug that lowers blood pressure, that could be dangerous," Annunziata said.
The good news, she added, is that two early trials are already underway to test the safety of giving beta blockers to ovarian cancer patients undergoing chemotherapy.
If the drugs are shown to be safe, Annunziata said, there will still be important questions: Which particular women could benefit? What doses work best? At what point during treatment should beta blockers be given?
"We still have a long way to go," she said.
Ovarian cancer is among the deadliest cancers because it's rarely caught early, before it spreads beyond the ovaries. About 45 percent of women are still alive five years after their diagnosis, according to the American Cancer Society.
The drugs work by blocking the effects of the "stress" hormone epinephrine (also known as adrenaline). And lab research suggests that epinephrine helps fuel the growth and spread of ovarian tumors, Sood explained.
His team found that non-selective beta blockers -- which are older formulations of the drugs -- were more strongly linked to ovarian cancer survival than newer, selective beta blockers were.
According to Sood, that supports the idea that beta blockers, themselves, have some effect. Non-selective versions have broad effects throughout the body, while the selective medications were designed to target the cardiovascular system alone.
Non-selective beta blockers include drugs like propranolol (Inderal, InnoPran), penbutolol (Levatol) and nadolol (Corgard). The selective type, which are now more commonly prescribed, include atenolol (Tenormin) and metoprolol (Lopressor, Toprol-XL).
The latest findings are based on records from 1,425 women treated for ovarian cancer at four U.S. medical centers. Overall, 75 women were on a non-selective beta blocker.
Those women, the study found, survived substantially longer than others, regardless of the types of cancer treatment they received. And there were no obvious differences between the two groups of women as far as age, weight or cancer stage.
However, there could have been other differences that played a role in longer survival, said Dr. Eva Chalas, chief of gynecologic oncology at Winthrop-University Hospital, in Mineola, N.Y.
She agreed that only clinical trials can answer the question of whether beta blockers have a role in ovarian cancer treatment.
But since the drugs might help by lowering epinephrine levels, that suggests stress reduction could be beneficial, Chalas said.
"If I were a woman with ovarian cancer, I'd look for ways to reduce stress in my life," she said.
"Some patients go through their Rolodex and literally remove people who stress them out," she said.
Annunziata made the same point. "It might be safer and more feasible to alter [stress hormones] without medication, by modifying your lifestyle and reducing sources of stress," she said.
Still, she added, researchers should continue studying beta blockers -- and not only for ovarian cancer.
"I think it would be useful to see whether they are associated with better survival in other types of cancer, too," Annunziata said.
The study was funded by the U.S. government and foundation grants.
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SOURCES: Anil Sood, M.D., professor, gynecologic oncology and reproductive medicine, University of Texas M.D. Anderson Cancer Center, Houston; Christina Annunziata, M.D., Ph.D., women's malignancy branch, U.S. National Cancer Institute, Bethesda, Md.; Eva Chalas, M.D., chief, gynecologic oncology, Winthrop-University Hospital, Mineola, N.Y.; Aug. 24, 2015, Cancer, online