Special Immune Cells May Improve Colon Cancer Survival Rates

University of Rochester Researchers Find New Benefit of Tumor-Fighting Cells

February 17, 2003

University of Rochester scientists discovered that certain white blood cells that carry a protein, originally thought to enhance cancer growth, may actually fight the progression of colon cancer and thus help patients live longer. This finding will assist oncologists in predicting which patients have a better chance of survival after treatment.

The protein, called VEGF, or vascular endothelial growth factor, is found in some white blood cells that gather around tumors. This type of white blood cell is called a macrophage. A retrospective study of colon tumor samples showed that patients who had macrophages with VEGF lived on average twice as long as patients without it – nine years compared to 4½ years. The study was published in the Feb. 15 issue of Cancer.

While doctors aren’t sure why those VEGF-rich cells combat disease, they know it plays a role in boosting the immune system during treatment. Scientists have long studied VEGF and its role in blood vessel growth. Until now, they believed VEGF stimulated tumor growth, but the University of Rochester study turned up new evidence that VEGF somehow plays a more positive role.

“This adds to the list of factors that can be studied to predict how patients will do in the long run,” said Alok A. Khorana, M.D., senior instructor at the UR James P. Wilmot Cancer Center. “It’s heartening because it suggests that the body’s response to cancer plays a significant role in containing the cancer. Finally, it gives us hope that boosting the immune system could be a new approach to reduce the chances of tumor recurrence after surgery.”

Khorana studied tumor samples from 131 patients with Stage II and III colon cancer treated at the Wilmot Cancer Center from 1990-95. Of that group, 70 percent of the patients were found to have macrophages surrounding the tumor, and 40 percent had macrophages that expressed VEGF. Those patients lived twice as long as the others.

Colon cancer is diagnosed in about 150,000 people every year in the United States. Standard treatment is surgery and chemotherapy, though about 50,000 people die from the disease every year. Khorana hopes to conduct clinical trials of a macrophage-stimulating drug in resectable colon cancer. The research was funded in part by Cancer Action/Gilda’s Club of Rochester and the Dr. Robert Cooper Endowed Fund. Khorana’s research is supported by the James P. Wilmot Cancer Research Fellowship. ##

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