Green tea extract may interfere with a process that helps early bladder cancer to spread throughout the body, new laboratory research suggests.

The findings, say researchers, bolster ongoing studies into green tea extract as a cancer treatment - and may give green tea drinkers more reason to savor every cup.

The investigators found that when they exposed human bladder cells to both a cancer-causing chemical and green tea extract, the extract interfered with a particular process by which early cancer cells become invasive and spread throughout body tissue.

This process involves the “remodeling” of actin, a structural protein in cells that is essential for cell movement. Actin remodeling allows cancer cells to move and invade nearby healthy tissue.

Based on the new findings, green tea extract may get in the way of this process by activating a protein known as Rho, which helps regulate actin’s organization in cells and has been implicated in tumor development and progression.

Dr. JianYu Rao and his colleagues at the University of California Los Angeles report the findings in the journal Clinical Cancer Research.

A number of studies have suggested that green tea and extracts of the beverage may have cancer-preventing abilities, possibly due to the tea’s concentration of certain antioxidants - compounds that help ward off cell damage that can lead to cancer, heart disease and other ills.

But exactly how green tea may act in the body to fight cancer is not clear. Lab research has suggested it can act in several ways - from hindering tumors from forming their own blood supply to forcing abnormal cells to commit suicide.

The current study points to an entirely new mechanism, Rao told Reuters Health in an interview.

Green tea extract, he explained, appears to diminish cancer cells’ invasiveness - suggesting that it could be used in the early stages of cancer treatment.

One recent study found that green tea extract brought no benefit to men with advanced prostate cancer. But Rao said that any effects of the extract on cancer would probably occur in the early stages.

He and his colleagues are now conducting a clinical trial to see whether green tea extract can reduce the risk of bladder cancer recurrence in patients with a history of smoking, which is a risk factor for the disease.

Uncovering the details of how green tea may stymie cancer could help doctors figure out which patients are likely to benefit from treatment with extracts, Rao said. It may be possible to look for specific markers of actin remodeling and Rho activation in patients’ urine to determine who is best suited for such therapy.

It’s also possible, Rao said, that drinking green tea could reduce the risk of developing bladder cancer in the first place - though no one knows how many cups a person would have to sip over a lifetime.

SOURCE: Clinical Cancer Research, February 15, 2005.