Advancement of science enables doctors to obtain a variety of markers in cancer tissues from a biopsy or after surgery of a particular cancer. Some of these markers are purely prognostic but some are targets for drugs that are already approved, or are being researched, although they may not be approved for this particular cancer. In other words, these drugs are already being used for the same targets in other cancer types. The ability to identify these markers enables doctors to provide Personalized Medicine, or a different personalized approach to each cancer. In the past, drugs were approved for specific cancers diagnoses, for example, for prostate cancer or for breast cancer and the like. With Personalized Medicine approach it is possible to use drugs based on their targets, even though the cancer that has the target is not the one for which studies of effectiveness of that particular drug have been conducted. A drug may have been approved for lymphoma but the target may be present in a pancreatic cancer, for example. This approach represents the cutting edge of diagnostic science, and it is referred to as, “Personalized Medicine”. It faces Cancer Medicine with a paradigm shift that it us finding difficult to assimilate, for it is logistically impossible and unaffordable to demonstrate effectiveness of a drug for a target in every cancer in which this target may be identified. It is entirely possible that a target or a mutation drives a malignancy of one type, but in another cancer it is merely a bystander. Without a demonstration of effectiveness, however, one cannot be sure that this target will truly prove to be the drivingone for this particular cancer, or that a Personalized Medicine therapy directed against it will really prove to be effective. Government and insurers are balking at paying for Personalized Medicine, seeing it as an expensive therapy that is based on a concept, and not solid research. The idea behind Personalized Medicine, that one can individualize cancer therapy based on specific tumor characteristics is attractive but needs to be proven before being widely adapted. As of now, there is little evidence to support Personalized Medicine beyond anecdotal reports and no guidelines or professional bodies recommending it. The potential of Personalized Medicine to transform cancer treatment, however, is immense.
Personalized medicine approach promises to supplant the current treatment paradigm in oncology. Traditionally and now, treatment focus was based on the particular cancer type and treatments were selected on how they did in large phase III trials. Drugs that did not show activity or had never been tested for a particular cancer type could not be used for that type with any kind of scientific credibility. More recently, an approach is taking shape that is based on the individual cancer in an individual patient. Tumor characteristics are studied with chemosenstitivity tests and one of a variety of genetic profiling tests that are now available, of which several are available. Specific mutations can be uncovered and then targeted with drugs approved for other cancer types that are targeted to this specific mutation or antigen. Unfortunately, the new paradigm does not “fit” well with the existing approaches and methods for weighing and evaluating evidence supporting cancer treatments, and new approaches to do so have not yet been developed.
Goldberger JJ, Buxton AE.. Personalized medicine vs guideline-based medicine.
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