"Findings from this study concern pure lung cancer that is not caused by smoking, and it gives us some wonderful new avenues to explore."
Little is known about the GPC5 gene, except that it can be over-expressed in multiple sclerosis, and that alterations in the genome where GPC5 is located are a common event in a wide variety of human tumors. "It may be that GPC5 holds different roles depending on the tissue type during various disease development and progression," Dr. Yang says.
A never smoker is defined as a person who has smoked fewer than 100 cigarettes in his or her lifetime, and that describes 15 percent of men and 53 percent of women who develop lung cancer -- accounting for 25 percent of all lung cancers worldwide, according to Dr. Yang. In the Western countries, between 10 and 15 percent of lung cancers occur among never smokers, but in Asian countries, 30 to 40 percent of lung cancers are never smokers, she says. "Our suspicion all along is that this is a distinct disease, and that is why we undertook this study," Dr. Yang says.
The research took two years and involved four steps. In the first step, conducted at Mayo Clinic, a genome-wide association study (GWAS) was performed on 377 never smokers with lung cancer, matched with 377 participants without lung cancer, the "control" population. This was the first GWAS ever conducted solely among never smokers, and it involved scanning the entire genome of every participant, looking for differences among 300,000 markers or so-called single-nucleotide polymorphisms (SNPs). The scan looks at everything -- inside and outside genes, coding and noncoding regions, Dr. Yang says. They found 44 "hits" -- hinting 44 areas on the genome that were substantially different between the lung cancer patients and healthy control population.
Then, to rigorously validate their findings in other populations, researchers launched stage 2. That involved using data from
|Contact: Karl Oestreich|