March 3, 2011
Test Identifies Aggressive Lung Cancer in Non-Smokers
(Ivanhoe Newswire) -- Lung cancer is considered the 6th most common cause of cancer deaths in the United States. Overall, 10-15% of lung cancers occur in people who have never smoked a single cigarette in their life. But thanks to an inexpensive and rapid testing method, scientists can now efficiently identify a sub-group of never-smoking lung cancer patients whose tumors express a molecule associated with increased risk of disease progression or recurrence.
It's a new test that could save the lives of non-smokers across the world. It was reported that between 8 percent and 12 percent of patients with lung adenocarcinoma who have never smoked cigarettes ultimately carry tumors that express a protein product called anaplastic lymphoma kinase (ALK).
"This subset of patients are at more than double the risk of experiencing disease progression or recurrence within 5 years of initial diagnosis compared to never-smokers whose lung adenocarcinoma tumors are ALK-negative," which Dr. Ping Yang from the Mayo Clinic, Rochester, USA, was quoted as saying.
Being able to text for ALK status in these patients could aid doctors in choosing suitable therapies for utmost clinical benefit. Dr. Yang's study aimed to determine whether immunohistochemistry screening, followed by a confirmatory test using fluorescence in situ hybridization (FISH), is the most practicable method to do this.
Immunohistochemistry tests employ antibodies in order to recognize particular proteins found in tissue sections. FISH uses fluorescent probes to join with certain DNA sequences in the chromosomes of individual cells.
The team of efficient examiners, using 303 samples for their study, reported that immunohistochemistry results associated well with the outcomes of FISH. Tissue samples with the maximum immunohistochemistry scores (IHC 3+) were all FISH positive, while those with no immunohistochemistry staining (IHC 0) were in due course FISH negative.
Dr. Yang further explains that throughout the study, only samples that were scored with the intermediate IHC scores of 1+ and 2+ would need confirmatory testing with FISH. "In this particular cohort, IHC score 2+ and 1+ cases represented approximately 27% of those screened. Even if confirmatory testing is done on all IHC 2+ and 1+ cases, confirmatory testing could be avoided on roughly three quarters of the cases."
"Because it is already performed in most pathology labs, testing can be done on-site versus sending a sample to another diagnostic testing site. Thus, IHC may be a good initial screening tool for ALK status," Dr. Yang added.
Conclusively, Yang and her colleagues established that 8.2 - 12.2 percent of the never-smoking group with lung adenocarcinoma had tumors that expressed ALK. The ALK positive tumors were drastically more aggressive as measured by tumor grade of differentiation and stage and were diagnosed in younger patients. However, there are no guidelines or standard protocols for ALK testing by IHC at the present time. Dr. Yang concluded that proper standardization and validation of IHC procedures for ALK testing are needed, including evaluating the effectiveness of different antibodies.
SOURCE: European Multidisciplinary Conference in Thoracic Oncology (EMCTO), Lugano, Switzerland, 24 "“ 26 February 2011