Cancer risk test for reckless smokers
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- Published 2.09.13
New Delhi, Sept. 1: Indian scientists have identified a genetic mutation that they say could be used to predict the risk of oral cancer for individual tobacco users and scare some into quitting or at least cutting their tobacco intake.
The researchers at the All India Institute of Medical Sciences (AIIMS), New Delhi, have found that a single difference in the genetic alphabet of a key gene increases the risk of oral cancer among tobacco users.
India has the world’s highest incidence of oral cancer with an estimated 100,000 new patients each year, and the use of tobacco — whether chewed or smoked — has been associated with an increased risk of oral cancer.
The AIIMS team examined a gene sequence called hMLH1 promoter and found that a point mutation — a change of a molecule from adenine (A) to guanine (G) — too is associated with an increased risk of oral cancer.
“We believe this could become a predictive marker to caution people who’re at very high risk,” Satya Narayan Das, a professor at the AIIMS department of biotechnology who led the research, told The Telegraph.
The hMLH1 gene is a key component of the cell’s protective and repair mechanisms that prevent cells from turning cancerous.
Several earlier studies from outside India had already established a connection between mutations in this gene and breast, colorectal and ovarian cancers.
Das and his colleagues examined the gene in 242 patients with oral squamous cell carcinoma and 205 healthy individuals and observed that a version of the gene termed hMLH1-93AA appears to be the wild type — the most common — among healthy Indians.
Their study, published this month in the international research journal Gene, has also shown that people who use tobacco and possess a version of the gene termed hMLH1-93GG have a 4.5-fold increased risk of developing oral cancer compared to those who possess the AA version.
“This is a significantly high risk ratio,” said Samir Brahmachari, a senior molecular biologist and director-general of the Council of Scientific and Industrial Research, New Delhi, who was not associated with the study but has been encouraging predictive genomics research.
“People who consume tobacco and have this version of the gene will know they’re at very high risk,” Brahmachari said.
Several Indian institutions, including private organisations, Brahmachari said, have the technological wherewithal to commercialise such a test and offer it to individuals “for certainly less than Rs 5,000”.
But scientists caution that the test will need to be validated in a larger sample population. “Cancer involves multiple genes — and the body has compensatory mechanisms that kick in when certain mutations are present,” said Rajesh Gokhale, director of the Institute of Genomics and Integrative Biology, New Delhi.
“This association would need to be validated through a sample of at least 1,000 patients and 1,000 healthy people.”
Doctors also caution that just scaring people may not be enough to get them to quit. “We have an estimated 270 million people in India who need to quit using tobacco,” said Pankaj Chaturvedi, a senior cancer surgeon at the Tata Memorial Hospital, Mumbai. “We need stronger pictorial warnings, and we need physicians who’ll routinely ask patients to quit tobacco —whether they’ve come for a fever or a stomach upset.”