In a significant medical breakthrough, researchers from the Tata Memorial Centre in Kharghar have pinpointed specific genetic factors that clarify why certain tobacco chewers in India develop oral cancer a full decade sooner than others. This landmark study offers the first genetic explanation for the varying age of onset observed in oral cancer patients across the country.
The Genetic Key to a Medical Mystery
For years, doctors have observed a puzzling pattern: some individuals use tobacco for decades without developing cancer, while others are diagnosed with the disease at a relatively young age. Dr. Pankaj Chaturvedi, director of ACTREC in Kharghar, highlighted this paradox, stating their research finally provides a concrete answer. The findings also shed light on why some people who have never used tobacco or similar carcinogenic substances still fall victim to oral cancer.
The extensive research, published in the prestigious journal 'eBioMedicine', part of The Lancet Discovery Science, analyzed a massive dataset. Over a 10-year period, the team examined genetic information from 2,160 cancer patients and 2,325 healthy individuals.
Pinpointing the Risk on Chromosomes
Led by Dr. Rajesh Dikshit and Dr. Sharayu Mhatre, the research team identified significant genetic risk areas located on chromosomes 5 and 6. These critical regions are situated near genes known as CLPTM1L-TERT, HLA-DRB1, HLA-DQB1, and CEP43. Dr. Dikshit further explained that a meta-analysis incorporating data from Europe and Taiwan uncovered novel risk loci near the NOTCH1 gene.
By calculating the cumulative effect of these genetic markers, the team established that tobacco chewers with a high genetic susceptibility developed oral cancer approximately a decade earlier than those with a low genetic risk. This finding is crucial in a country like India, which records about 1.4 lakh (140,000) new oral cancer cases every year, with incidence rates soaring as high as 33 per 1 lakh population in some states.
Implications for Prevention and Public Health
Lead author Dr. Sharayu Mhatre emphasized that while tobacco use remains the single strongest risk factor for cancers of the buccal mucosa (inner cheek), a genetic susceptibility component undeniably plays a significant role. Dr. Chaturvedi provided a stark comparison, noting that the risk of developing oral cancer is 26 times higher among tobacco chewers compared to non-users. For those with a high genetic risk score, these susceptibility markers can double the risk even further.
However, Dr. Sudeep Gupta, director of TMC, issued a critical reminder. While understanding genetic susceptibility is important, tobacco chewing remains the most preventable cause of oral cancer. He stressed that over 80% of oral cancer cases could be avoided through effective tobacco control policies and public awareness.
The international scientific community has welcomed the study. A press release quoted Dr. Siddhartha Kar from Cambridge University, who described it as a 'landmark study' that advances the global understanding of why oral cancer is so prevalent in India. He noted that by revealing how inherited risk interacts with tobacco use, the research lays the essential groundwork for targeted prevention and early detection strategies.
