July 16 (HealthDay News) -- Using the drug thalidomide in combination with chemotherapy won't improve survival for patients with small cell lung cancer but does increase their risk of blood clots, an English study finds.

For the study, 724 patients were randomly assigned to take a placebo or thalidomide, which suppresses angiogenesis, the formation of new blood vessels that tumors need to survive and grow. The patients took 100 to 200 milligrams a day of thalidomide or the placebo for up to two years.

Median overall survival for patients in the thalidomide group was 10.1 months, compared to 10.5 months for those in the placebo group. Patients who took thalidomide had a higher risk of blood clots.

Thalidomide is used to treat some other cancers, including multiple myeloma and colorectal cancer, but doesn't appear to work as well in patients with small cell lung cancer. This may be because of differences in the tumor blood-vessel growth pathways involved in small cell lung cancer, suggested Dr. Siow Ming Lee of University Hospital in London and colleagues.

The study appeared online July 16 in the Journal of the National Cancer Institute.

This and other negative results from previous studies indicate the need to take a new look at the basic biology of small cell lung cancer and the supposed ability of thalidomide to suppress tumor blood-vessel formation, experts at the University of Lausanne in Switzerland wrote in an accompanying editorial.

"Rather than running from failure to failure, it may be more reasonable to go back to experimental work, including the development and analysis of transgenic SCLC (small cell lung cancer) models, to better understand SCLC biology and identify robust therapeutic targets," recommended Dr. Curzio Ruegg and Dr. Solange Peters.

SOURCE: Journal of the National Cancer Institute, news release, July 16, 2009