Tests to tailor cancer treatment to patient needs
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- Published 2.10.13
New Delhi, Oct. 1: Sections of cancer patients in India could now have their tumours genetically profiled through a new set of tests that doctors say will help them optimise treatment strategies and avoid unnecessary chemotherapy.
The tests, offered by two US academic institutions and introduced in India by the Rajiv Gandhi Cancer Institute and Research Centre (RGCIRC), New Delhi, look for mutations in select genes that will help doctors tailor treatment strategies for individual patients.
The tumour profiling tests, available for cancers of the breast, colon, lungs, ovaries, prostate, thyroid, and acute leukemia, are intended to help doctors prescribe the most appropriate chemotherapy agent, RGCIRC doctors said.
“Conventional chemotherapy and radiotherapy is like one-shoe-fits-all,” said Anurag Mehta, director of laboratory services at the RGCIRC. “Through tumour profiling, we’re trying to introduce personalised medicine.”
Over the past decade, genome studies of tumours have established that cancers of the same organ can be sub-classified according to what oncologists call “driver mutations”, genetic mutations that drive tumour growth or its spread. Scientists have also developed several new drugs that have shown great promise as novel chemotherapy agents as they’re designed to neutralise the effects of driver mutations.
A mutation in a gene called Kras, for instance, has been observed in earlier studies to exist in about 40 per cent of patients with colon cancer. But this mutation is associated with a very poor response to a medicine called erbitux.
Through tumour profiling of colon cancer, doctors say, about 40 per cent of patients could be spared of the costs and side-effects from what for them would be ineffective treatment.
“Such tests will make a difference in cutting out unnecessary treatment,” Rajendra Badwe, director of the Tata Memorial Hospital, Mumbai, told The Telegraph. The Tata Memorial also offers the test to screen colon cancer for the Kras mutation.
“But such targeted treatment based on the test is prohibitively expensive and offers small benefits — not more than 5 per cent of those who need such treatment can afford it,” Badwe said. “But it is an advance that needs to be made available.”
The RGCIRC will send tissue samples from patients to laboratories at the Yale School of Medicine and the Thomas Jefferson University in the US for tumour profile studies and expects to receive results within seven to 10 days. It has said the test will cost about $3,000 (Rs 1.8 lakh approx.) for a patient.
The tumour profiling tests look at eight genes and 69 mutations across all the cancers for which such tests are currently believed to be useful. “We’re looking for actionable mutations for which specific drugs are available,” Mehta said.
Many oncologists believe the technology, while promising, would be considered expensive in India. “These tests are useful, but for $3,000, patients in India could complete conventional chemotherapy and radiotherapy,” Ramamurthy Rajaraman, president-elect of the Indian Society of Surgical Oncology and head of the Centre for Oncology at the Government Royapettah Hospital, Chennai, told this paper.
After the profiling test, prescribed therapy too may be expensive for some patients. An oncologist in New Delhi recalled a recent case of a 57-year old woman diagnosed with lung cancer. Her tumour profile tests revealed a mutation that suggested her tumour could be treated with a drug that cost her about Rs 80,000 a month.
A senior oncologist also said the survival benefits from some of the new drugs still need to be well-documented. In lung cancer, for instance, median survival time with conventional treatment is about five months, and increases to about 11 months with drugs designed against a specific genetic mutation.