Growth Hormone Linked to Cancer
Safety of Popular Anti-Aging Treatment Questioned
Pollak, director of the cancer prevention unit at Canada's McGill University in Montreal, is co-author of an editorial published alongside the Swerdlow study. The editorial supports Swerdlow's worry that hGH has a role in cancer -- especially colon cancer.
One effect of hGH is to raise blood levels of a substance called insulin-like growth factor type I (IGF-I). Animal studies show that high levels of IGF-I cause cancer. Colon-cancer cells grow faster when exposed to IGF-I. People with a disease called acromegaly have too much IGF-1 in their blood -- and they are at high risk of colon cancer.
"The fact that these hormone levels decline with age may be an appropriate balance," Pollak says. "You may be subjecting yourself to risks if you keep these levels high."
In an October 2000 interview with WebMD, Stanley Slater, MD, discussed the fad of using hGH to slow the aging process. Slater is associate director for geriatrics at the U.S. National Institute on Aging.
"When people ask, I tell them not to take growth hormone but to wait until it is clinically established to be useful," Slater says. "There is no clinical evidence of it causing tumors to grow faster, but on biological grounds there is some suspicion. If you give someone growth hormone for 30 years, nobody knows what will happen."