Androgen, or male hormone, may be responsible for the higher morbidity of liver cancer among men than women, researchers at the Chinese University of Hong Kong (CUHK) have found.

The finding, which reveals a high possibility of androgen's direct influence on activating liver cancer cells, may be a breakthrough in understanding why men tend to be more susceptible to liver cancer.

Researchers of the Institute of Digestive Disease at the university discovered that 70 percent of 50 liver cancer patients held high levels of a gene called cell cycle-related kinase (CCRK), which is directly controlled by androgen receptors.

The patients were more likely to have late-stage cancers and also had shorter life expectancy than those with low CCRK level.

Using mouse models, the researchers also found that either lowering the level of CCRK or blocking the signaling pathway in cancerous liver cells may significantly reduce tumor growth rate.

Feng Hai, one of the researchers at the institute, explained that CCRK genes exist in every human body, but are like seeds which normally cannot be seen or seldom discovered in the liver.

With stimulation from androgen, CCRK becomes activated and starts to function abnormally, triggering swift proliferation of liver cells which eventually result in liver cancer.

Therefore, when both a man and a woman carry hepatitis B - an illness that can easily evolve into liver cancer - a man has higher chance of falling victim to the onset of cancer because of the male hormone.

Researchers have yet to conduct therapeutic tests on mouse models before going to the next step to confirm the relationship. Nor has there been any clinical trial.

The researchers said there is a long way to go before discovering the means to cure the lethal form of cancer, even if the relationship is proven ultimately.

"We do hope that we could work out the remedy within five to ten years," said Joseph Sung, vice-chancellor and a medical professor of the CUHK.

Sung also said that any medical methods intended to inhibit CCRK should carefully factor in the possibility to kill other innocent genes and create side effects.

Previously, a widely accepted finding has shown that the female hormone, estrogen, serves as protection and reduces the chance of getting liver cancer, said Sung.

Liver cancer is the fourth most common cancer - and also the third most fatal cancer in Hong Kong, following lung cancer and colon cancer, according to the Hong Kong Cancer Registry of the Hospital Authority.

The morbidity of liver cancer in males in Hong Kong is three times higher than females.

For Asia and Africa in general, where hepatitis B is more prevalent, liver cancer is seen seven times more frequently in men than women.

In the West where hepatitis B is less prevalent, the gender bias appears less obvious, researchers said.

andrea@chinadailyhk.com

China Daily

(HK Edition 07/20/2011 page1)