Testicular tumors

Keeping cholesterol in check not only benefits heart health, it may also delay the progression of prostate cancer, suggests a mouse study from Boston Children's Hospital.

When mice with human prostate tumors were given the cholesterol-lowering drug ezetimibe (Zetia) along with a no-cholesterol diet, their tumors were smaller and grew more slowly. Mice receiving the drug, regardless of their diet, also had about a 50 percent reduction in angiogenesis, or blood-vessel growth, when compared with untreated mice on a high-cholesterol diet. "It caught my attention almost immediately that there was a great deal more blood in some tumors than in others," says Keith Solomon, PhD, of the Departments of Urology and Orthopedic Surgery, who led the study.

The findings suggest that ezetimibe slows the growth of prostate tumors, at least in part, by inhibiting angiogenesis. This surprised Solomon, who'd hoped only to show that raising cholesterol accelerates tumor growth and that reducing cholesterol curbs growth. He speculates that cholesterol gives tumor cells, and cells in the surrounding environment, material to encourage angiogenesis.

"The anti-angiogenic effect of cholesterol-lowering implies that these findings may have relevance to other tumor types," notes Michael Freeman, PhD, of Children's Department of Urology, the study's senior author.

Population studies have linked prostate cancer with high cholesterol levels and Western diets high in cholesterol. In 2005, the Solomon and Freeman groups showed that cholesterol helps prostate tumors survive and grow at the cellular level by altering chemical signaling patterns.

Since most prostate tumors are slow-growing, Solomon speculates that some men can delay medically significant cancers, and perhaps avert them altogether, by aggressively managing their cholesterol levels. "A 20 to 30 percent reduction in cholesterol might not affect a fast-growing tumor, but could have a significant effect on a slow-growing tumor, allowing men to avoid surgery," he says. The study appears in the March issue of The American Journal of Pathology.