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Possible New Tumor Classification

Posted 8/11/2014

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  This is potentially very big scientific news that applies to all kinds of cancer, not just breast. Scientists have just announced, in an article in Cell, that totally new approach to classifying tumors may change the treatment for at least one in ten cancers.

  As you know, cancers are currently classified by their place of origin: breast cancer, lung cancer, kidney cancer, etc. If a cancer metastasizes it is still the same type. This means that breast cancer that spreads to the lung is "breast cancer that has metastasized to the lung", not lung cancer. This matters because different kinds of cancers respond to different drugs, so it is important to be clear what it being treated.

  Researchers with The Cancer Genome Atlas (TCGA) have found that cancers are more likely to be molecularly and genetically similar to one another based on the kind of cell of origin, not the place of origin. This means, for example, that a breast cancer could be more genetically similar to a prostate cancer than to another breast cancer. Like everything else in science, this is a long way from prime time and will need to be further explored and tested before it impacts clinical care. This is an exciting step forward.

  Here is the start of a summary from Eureka Alert and then a link to read more:

Largest cancer genomic study proposes 'disruptive' new system to reclassify tumors

TCGA scientists analyzed the DNA, RNA and protein from 12 different tumor types using six
different TCGA "platform technologies" to see how the different tumor types compare to each
other. The study showed that cancers are more likely to be molecularly and genetically similar
based on their cell type of origin as opposed to their tissue type of origin (e.g. breast, kidney,
bladder, etc.). Benz, a senior author on the paper points out that most of our tissues are
composed of many different types of epithelial and non-epithelial cells. "This disruptive genomic
study not only challenges our existing system of classifying cancers based on tissue type, but also
provides a massive new data resource for further exploration as well as a comprehensive list of
the molecular features distinguishing each of the newly described cancer classes," said Benz.
"Examples like the proposed reclassification of bladder cancer into several different cancer
classes, each with distinct clinical outcomes, help explain why patients often respond very
differently when treated with the same systemic therapy for their seemingly identical cancer
The study team suggests that at least one in ten cancer patients would be classified differently
under this new system. But Benz thinks this fraction of tumors needing reclassification will swell
when more samples and additional tumor types are included in the next round of analysis,
anticipated to involve more than 20 different tumor types. "We're just appreciating the tip of the
iceberg when considering the potential of this multi-platform type of genomic analysis. It could be
that as many as 30 or 50 percent of cancers need to be reclassified."


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