Results from a large study shows that adding shark cartilage extract to standard chemotherapy and radiation therapy for patients with advanced non-small cell lung cancer does not improve survival.

The findings were released here Sunday at the annual meeting of the America Society of Clinical Oncology.

Non-small cell lung cancer is the most common type of lung cancer, comprising nearly 80 percent of cases. This study focused on patients with advanced disease that cannot be surgically removed; such patients are typically treated with a combination of chemotherapy and radiotherapy.

Shark cartilage products have been marketed as alternative medicine cancer "cures" that work by blocking the formation of blood vessels that feed tumors.

Various forms of shark cartilage have been studied in the past, none of which showed a survival benefit. This trial evaluated the shark cartilage extract Neovastat in 384 patients at 53 sites in the United States and Canada.

Patients were randomized to receive either the standard treatment plus shark cartilage or the standard treatment plus placebo. The extract was given to patients as liquid, which they drank twice a day.

After a median follow-up of 3.7 years, investigators found no significant difference in overall survival between the two group ( 14.4 months for the shark cartilage arm versus 15.6 months for the placebo arm).

"These results definitively demonstrate that this shark cartilage extract is not effective against lung cancer when combined with chemoradiotherapy," said Charles Lu, associate professor at The University of Texas and the study's lead author. "These negative results are disappointing, but this study shows the benefit of conducting scientifically rigorous studies on potential anti-cancer agents, including those that some may consider to be alternative therapies."

Source: Xinhua