QDIS Blog

Today seems to be genetic testing day on this blog. Reuters had a report recently on a new genetic test that will likely find great use in oncology.

Test to predict response to chemotherapy drug | Top News | Reuters.com

This is exciting news. Basically, people with lung cancer that express a gene called ERCC1 will likely not respond to cisplatin. For these patients, other chemotherapy should be considered. While not proven yet in large studies, this is interesting and might in the future allow oncologists to select the proper treatment based on genetic testing. Since chemotherapy can have devastating side effects, it is important to get a treatment that has the highest probability of success for a given patient. If you are one of those who would not respond to a given drug, regardless of how effective it is in the given population, you would want to know that before going through a treatment with nasty side effects that won’t work for you. The fact that 75% of people respond doesn’t do you any good if you are in the 25% group. I also think that until recently there seemed to be much more emphasis on finding genes that indicated a person would respond to treatment rather than identifying those who would not respond. I think both are important and in the case of oncology identifying those who would not respond is very important to avoid going through a treatment that causes serious side effects but with no really benefit.

Another example is the HER2 and Herceptin. Women with early breast cancer who have higher levels of HER2 are at significant increase risk of the disease recurring and worst prognosis. However, these very patients respond quite well to treatment with Herceptin. This test is routinely used now for women with breast cancer.

I see this as the future of personalized medicine and not the process of making a specific compound for an individual. Finding out who will and who will not respond to a given treatment will be of tremendous importance to medicine in the 21st century.

Other Sources

• HER2/neu - Wikipedia, the free encyclopedia
• NEJM — HER2 and Responsiveness of Breast Cancer to Adjuvant Chemotherapy
• Adjuvant Trastuzumab: A Milestone in the Treatment of HER-2-Positive Early Breast Cancer — Baselga et al. 11 (Supplement 1): 4 — The Oncologist
• Low ERCC1 Expression Correlates with Prolonged Survival after Cisplatin plus Gemcitabine
• Chemotherapy in Non-Small Cell Lung Cancer — Lord et al. 8 (7): 2286 — Clinical Cancer Research

Search Results

• her2 - Yahoo! Search Results
• her2 - Google Search
• ERCC1 - Google Search
• ERCC1 - Yahoo! Search Results

Technorati Tags: chemotherapy, cisplatin, genetic testing, Herceptin, personalized medicine, trastuzumab

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Lately I’ve been thinking about genetic testing and its proliferation recently, especially those available by mail. A lot of those advertising are paternity related but others cover a wide variety of diseases.

CBS News recently had a good article about this.

Home Genetic Tests For Disease - CBS News

One of the problems with these mail-in testing is that, in the vast majority of cases, there is no counseling involved. What about the situation where a woman has sent in a DNA testing for breast cancer and the results come back that she has the gene in question. What does this mean to her? Does that mean she will definitely develop breast cancer? All of these are sure to be though about and without any access to genetic counseling how are they to get answers. Hopefully, most would turn to their primary care physician but some studies indicate they aren’t informed on what these various genetic testing results mean.

Seems that in some cases, these are like the old snake oil salesmen. They claim to test for all sorts of things but don’t disclose the limitations. There is also the worry of counseling if the results are potentially devastating. THen there is the fact that this industry is largely unregulated.

I think this area will be one that sees a dramatic increase in use in the next few years but like any tool, it needs to be used correctly. I can’t say, based on what I know now, that I think the mail order genetic testing is worth the cost, both monetary and psychological. This is another case where science is far ahead of public policy.

Other Resources

Genetic testing - Wikipedia, the free encyclopedia
DNAPolicy
Talk to Your Doctor or Healthcare Practitioner About Home Genetic Tests

Technorati Tags: genetic testing

Email Ed Vawter

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