Sputum Test Could Help Screen For Lung Cancer

NEW YORK MAR 20, 2006 (Reuters Health) - Testing sputum samples for gene promoter hypermethylation may help identify high-risk patients who are likely to develop lung cancer, according to a report in the March 15th issue of Cancer Research.

The findings also indicate that the extent of hypermethylation is inversely related to the time before the lung cancer is diagnosed. 

"Short of repeatedly x-raying a person"s lung to look for emerging tumors, there is no way now to screen people at high risk for lung cancer, much less predict who will be diagnosed with the cancer at a later date," senior author Dr. Steven Belinsky, from the Lovelace Respiratory Research Institute in Albuquerque, New Mexico, said in a statement.

He added that if perfected and validated, tests like the one his group studied could hold "great promise for identifying people with lung cancer early enough to successfully treat them."

In the present study, the researchers looked for promoter hypermethylation in 14 genes in sputum samples from 98 patients who later developed lung cancer and 92 matched controls.   

Gene promoter hypermethylation was more pronounced in sputum samples obtained within 18 months of lung cancer diagnosis compared with samples taken > 18 months before diagnosis. 

Six of the genes tested were strongly linked to lung cancer, increasing the risk by >50%, the report indicates.  If three or more of these genes showed promoter methylation, the risk of lung cancer increased 6.5-fold with a sensitivity and specificity of 64% -- clearly not accurate enough yet for clinically use. 

Dr. Belinsky noted that his group is now looking for other genes linked to lung cancer to improve the predictability of the sputum test.

SOURCE:

• Cancer Res 2006;66:3338-3344.