A first in a series of Tata Memorial Hospital’s research papers on gall bladder cancer, published in the Lancet Oncology on Monday, has found mutation in two genes responsible for high incidence of cancer in North and Northeast India along the Ganga and Brahmaputra belt. Northern India and Chile are globally the only two regions with high incidence of gall bladder cancer, which has prompted researchers to look for answers.
This was the first time a largescale study involving 1,400 patients was undertaken by the Parel-based hospital along with the United States National Cancer Institute.
The research team studied over 7 lakh single nucleotide polymorphisms (SNPs) in patients. SNPs make up the genes in a body. The research found that all patients had mutations of the ABCB4 and ABCB1 genes, which may be responsible for increased risk of gall bladder cancer.
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The Indian Council of Medical Research (ICMR) is going to conduct research in north India following the Lancet report to understand the causes for and treatment of the disease.
“Gall bladder cancer has high variability in India. It is common in some regions and absent in others. ICMR will do further research,” said ICMR director Dr Saumya Swaminathan.
Gall bladder cancer’s incidence is 14 per lakh population in women and 7.4 per lakh population in men in regions where the Ganga and Brahmaputra rivers flow. In other parts of India, the incidence is close to zero, with South India having incidence of 0.7 per lakh population.
“ABCB4 and ABCB1 genes are responsible for transport mechanisms from the liver to gall bladder. Mutation in ABCB4 and ABCB1 gene can affect bile formation and increase salt in body. This can cause cancer,” said the author of the study, Professor Rajesh Dikshit.
According to another author of the study, Dr Preetha Rajaraman of the National Cancer Institute, the mutation can increase gall bladder cancer risk by 50 per cent. “This research opens up scope for more study. This is the first time such a large research on the gall bladder has been conducted to point at gene mutation,” she said.
The Tata Memorial Hospital, along with Banaras Hindu University and the Dr B Borooah Cancer Institute in Guwahati, will work on research papers to measure if gall bladder cancer is caused by heavy metals found in the Ganga and the Brahmaputra, if local tobacco and mustard oil consumption may be responsible, and whether specific bacteria found in the two rivers could lead to increased cancer risk.
“Our future research will throw more light on whether a cluster of factors, including genetic mutation, are responsible for gall bladder cancer. This cancer is being passed on for generations in that belt,” said principal author Dr Sharayu Mhatre.
Gall bladder cancer is usually detected in advanced stages because of lack of symptoms to help early detection. At least 70 per cent patients are diagnosed in the advanced stages which leaves them with three to five years to live. The initial symptoms are mild stomach pain and gas formation, which develops into jaundice in advanced stage.