Study Links a Protein to Cancer Spread

High Cox-2 Levels Indicate Aggressive Tumors in Men With Prostate Cancer

From the WebMD Archives

Nov. 8, 2006 (Philadelphia) -- In men with prostate tumors, cancer is more likely to spread to other parts of the body if they have high levels of the protein Cox-2 before starting radiation therapy, researchers report.

The study "suggests that looking at Cox-2 expression in biopsy samples taken before radiation treatment could determine which men have aggressive tumors that need more aggressive treatment," says researcher Li-Yan Khor, MD. She is a research fellow in the radiation oncology department at Fox Chase Cancer Center in Philadelphia.

Cox-2 is a protein that is involved in inflammation. Painkillers known as Cox-2 inhibitors reduce inflammation by blocking Cox-2 activity.

The study's findings -- although not tested yet -- suggest that Cox-2 inhibitors such as Celebrex might help curb the growth of prostate tumors, Khor tells WebMD.

She notes that animal and laboratory studies have suggested that blocking Cox-2 seems to sensitize cancer cells to radiation treatment and chemotherapy, thereby slowing tumor growth.

Louis Potters, MD, medical director of the Prostate Institute in Oceanside, N.Y., agrees that a study testing whether Cox-2 inhibitors shrink prostate tumors seems a logical next step.

"But any studies testing that hypothesis have to proceed carefully, with the known cardiovascular risks of the drugs weighed against any potential benefit," he says.

Cox-2 and Cancer Spread

For the study, presented here at the annual meeting of the American Society for Therapeutic Radiology and Oncology, Khor and colleagues analyzed Cox-2 levels in biopsy samples from 586 men who had undergone radiation and hormone therapy.

By five years after treatment began, cancer spread to other parts of the body in 11% of the men with lower Cox-2 levels vs. 14% of the men with higher levels.

Men with lower levels of Cox-2 were also more likely to remain cancer-free, as determined by negligible blood levels of PSA, a protein produced by the prostate. Rising PSA levels are thought to be a sign of cancer recurrence after treatment.

Testing Could Help Guide Treatment

Oncologists can recommend that men with prostate cancer be given hormone therapy after they undergo radiation treatment or surgery. Also known as androgen-deprivation therapy, hormone therapy lowers the level of male hormones in the body, thereby slowing the growth of prostate tumors.

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Studies have suggested it can add years to men's lives. But there are side effects -- chiefly reduced sexual desire, impotence, hot flashes, weakening of the bones, and breast tenderness or breast growth.

The new findings suggest that measuring Cox-2 levels can help doctors to decide which men need long-term hormone therapy and which men could safely have a shorter three-month course, with fewer side effects, Khor says.

Potters agrees. "One of the big paradoxes in prostate cancer is that we don't have enough information to figure out which patients will rapidly progress. There are a good number of men who can live out their lives after a prostate cancer diagnosis without ever needing treatment and others whose disease is rampant and will rapidly progress without treatment," he tells WebMD.

"Having new markers that can predict whose cancer will spread, as this study says Cox-2 seems to do, will let us better tailor therapy," Potter says.

WebMD Health News Reviewed by Louise Chang, MD on November 08, 2006

Sources

SOURCES: American Society for Therapeutic Radiology and Oncology's annual meeting, Philadelphia, Nov. 5-9, 2006. Li-Yan Khor, MD, research fellow, radiation oncology department, Fox Chase Cancer Center, Philadelphia. Louis Potters, MD, medical director, Prostate Institute, Oceanside, N.Y.

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