NCCS Study Reveals Why Your Ethnic Group Matters In Cancer Treatment.
Thursday, 19 January 2006
Singapore, 19 January 2006 - A National Cancer Centre Singapore (NCCS) study has thrown some light on why some cancer patients respond better to treatment while others don't, despite being given the same dose of drugs. Scientists at NCCS have carried out translational research on genetic polymorphisms in the different ethnic groups. Genetic polymorphisms are single base changes in genetic DNA molecules.
The findings suggests that polymorphisms in our UGT1A1 gene might help identify cancer patients at high risk of toxicity when treated with the chemo drug irinotecan.
Dr Balram Chowbay (Sr Clinical Pharmacologist, Division of Medical Sciences NCCS) and Dr Tan Eng Huat (Senior Consultant, Medical Oncology, NCCS) developed a study to identify functional genetic polymorphisms in several genes. These polymorphisms affect the metabolism of irinotecan in cancer patients belonging to different local ethnic groups. The study revealed:
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a polymorphism in the UGT1A1 gene associated with decreased ability of the patient to detoxify the drug. This would potentially put a patient receiving irinotecan at increased risk of toxicity. The patient might suffer from severe diarrhoea or severe neutropenia1. |
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an alignment with earlier research showing that 13% of Indians compared with 2% to 4% of Chinese and Malays possess this polymorphism in the UGT1A1 gene. |
This finding suggests that Indians may be more sensitive to irinotecan compared to patients belonging to Chinese and Malay ethnic groups. In future doctors might thus consider administering a different dosage of this drug or consider an alternative treatment regimen', explains Dr Balram.
Such translational research is welcomed by doctors. 'These research findings specific to our local cancer patients are exciting. Pharmacogenomics2 helps us to continually improve our treatment of cancer patients ' said Dr Koo Wen Hsin, Head Medical Oncology, NCCS.
The project took 4 years to complete and Dr Balram Chowbay and his team were funded by Singapore Cancer Syndicate, a branch of A-Star.
1 An abnormal decrease in the number of neutrophils in the blood.
2 the science of customizing therapy with drugs according to a patient's genetic make-up
Genetic Polymorphisms and Ethnic Differences
Genetic polymorphisms refer to different forms of the same gene in different individuals. Most of these variations arise from single base changes in the DNA molecule. The frequency of a particular polymorphism's occurrence may vary between different ethnic groups. Such changes may be associated with altered production and functions of proteins in the body such as the drug metabolising enzymes. As a result, patients who have such polymorphisms may be unable to detoxify their drugs as efficiently as other patients who do not carry the polymorphism.
Pushing Boundaries of Genomic Medicine
Such cutting edge global research has pushed the boundaries of medical knowledge on the specific behaviour of genes that make us resistant to certain treatment. 'These pharmacogenetic discoveries have significant implications on cancer therapy given our local multiethnic population. As a center of excellence for cancer care, we are constantly fine-tuning and tailoring cancer treatment, ' said Prof Soo Khee Chee, Director NCCS.
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