New DNA Tests Aimed at Reducing Colon Cancer
On Thursday, two new tests were described that could detect signs of colon cancer early. Early detection would allow doctors to remove precancerous and cancerous tumors before they develop into full fledge cancer. The use of these tests would also reduce the $14 billion cost of treating the disease in the US.
The fist test was developed by Exact Sciences and uses stool samples to spot four genes diagnostic of colon cancer. The second test developed by Epigenomics in Germany looks in the blood for changes in another gene called Septin 9. Both of these DNA tests are noninvasive and patients would be able to avoid uncomfortable colonoscopies, where a tube with a camera is inserted in the colon. These are also less expensive than getting a colonoscopy and could prove to be better since colonoscopies sometimes miss tumors in the upper parts of the intestine.
Both of these tests’ potential depends on their sensitivity and specificity. Exact Science said that tests were very specific and sensitive but when only tumor cells were tested. In actual stool tests, the numbers could be less promising since most of the DNA comes from the bacteria of the gut and only 0.01% is human DNA.
The advisor of Exact Science mentioned that stool tests must be 90% specificity, and now they are at 88%, not too far off. Epigenomics tests had a specificity of 93%. The only problem with Epigenomics is that the Septin 9 gene detected might not always develop into cancer, so the test might not make much sense economically. Overall though, with further research these tests could be very promising.
I found this article very interesting because a lot of research lately has been toward cancer, and even though no cure has been found yet, it is reassuring that groundbreaking progress is being made. In the article for example, it is mentioned how if “widely used, and regularly, [the tests] really do have the opportunity to eliminate colon cancer.”
http://www.nytimes.com/2010/10/29/health/29cancer.html?ref=health
The fist test was developed by Exact Sciences and uses stool samples to spot four genes diagnostic of colon cancer. The second test developed by Epigenomics in Germany looks in the blood for changes in another gene called Septin 9. Both of these DNA tests are noninvasive and patients would be able to avoid uncomfortable colonoscopies, where a tube with a camera is inserted in the colon. These are also less expensive than getting a colonoscopy and could prove to be better since colonoscopies sometimes miss tumors in the upper parts of the intestine.
Both of these tests’ potential depends on their sensitivity and specificity. Exact Science said that tests were very specific and sensitive but when only tumor cells were tested. In actual stool tests, the numbers could be less promising since most of the DNA comes from the bacteria of the gut and only 0.01% is human DNA.
The advisor of Exact Science mentioned that stool tests must be 90% specificity, and now they are at 88%, not too far off. Epigenomics tests had a specificity of 93%. The only problem with Epigenomics is that the Septin 9 gene detected might not always develop into cancer, so the test might not make much sense economically. Overall though, with further research these tests could be very promising.
I found this article very interesting because a lot of research lately has been toward cancer, and even though no cure has been found yet, it is reassuring that groundbreaking progress is being made. In the article for example, it is mentioned how if “widely used, and regularly, [the tests] really do have the opportunity to eliminate colon cancer.”
http://www.nytimes.com/2010/10/29/health/29cancer.html?ref=health
posted by Belen Berdegue at 8:35 PM
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