The University of Hong Kong (HKU) has identified tumor-producing cells capable of maintaining resistance to chemotherapy and resulting in recurrences of liver cancer.

Liver cancer is the third most deadly form of cancer in Hong Kong.

More than 1,700 new cases of liver cancer are reported each year.

The leading cause is hepatitis B virus. About 10 percent of the city's population are hepatitis B virus carriers transmitted mainly through maternity.

At present, removal of tumors and liver transplants are the mainstays of treatment. Advanced patients are able to undergo conventional chemotherapy and local ablative therapies.

Results from chemotherapy and ablative therapy are considered unsatisfactory. In both there are high rates of recurrence and mortality. No more than 25 percent of liver cancer patients are able to receive first line treatment because in the majority of cases, there is late diagnosis of liver cancer.

Compounding the problem is a limited supply of liver grafts, explained professor Irene Ng from the Department of Pathology at HKU's Faculty of Medicine.

"The main hurdles in treating liver cancer are a high chance of tumor recurrence even after surgical resection and that the tumor is resistant to chemotherapeutic drugs," Ng said.

When cancer recurs, it often does so in a treatment-resistant form or it is widely spread. For many patients, relapse presages failure of all treatment.

"Therefore, understanding the mechanism of tumor recurrence and chemoresistance will help improve treatment results," Ng said.

According to a study led by Professor Ng, liver cancer patients whose cancer stem cells had high expression of a protein known as CD24+ had a significantly high risk of tumor recurrence and metastasis through activation of another protein labelled as STAT3.

"The CD24+ is like a button, when the button is turned on, it will trigger a lot of activation within the cell and one of the main targets is STAT3," Ng explained.

Research Assistant Professor Terence Lee said that liver cancer patients whose tumor have high CD24+ expression had three times higher risk of tumor relapse in the first year after surgery when compared to those with low CD24+ expression.

Patients having low expression of CD24+ lived seven times longer (42 months) than their high expression counterparts (6.6 months), Lee added.

However, the new targeted drugs, which would not be marketable for 10 years at the earliest, may help patients prolong life and reduce unwanted side-effects even though they cannot be used to cure the disease completely.

The HKU is conducting a further study to evaluate therapeutic efficacy of STAT3 inhibitors in the suppression of liver cancer relapse and its combined effect with traditional chemotherapy.

mingyeung@chinadailyhk.com

China Daily

(HK Edition 07/08/2011 page1)