New Report Recommends Classifying Cancer by Genetic and Molecular Type

(August 21, 2014) A research network in the US proposes that cancer should be classified according to genetic and molecular features rather than by the type of tissue in which the tumor arises. While more work is needed to confirm and build on the findings, the scientists say such a system would be better for patients because it would help tailor treatment to their individual needs.  The findings were published this month in Cell.

This latest study found even across tissue types (for instance, breast, bladder and kidney), what we currently regard as different cancers have tumors that are more similar at the molecular and genetic level than at the tissue level.

For the study, the scientists compared the DNA, RNA and proteins of 3,527 specimens of 12 different tumor types by analyzing them with six different “platform technologies.” The results showed tumors were more likely to be molecularly and genetically similar based on their cell type of origin as opposed to their tissue type of origin.

For example, the study suggests there are at least three different subtypes of bladder cancer, one of which is almost identical to lung adenocarcinoma, and another that is similar to squamous cell cancers found in the head-and-neck and lungs.

The study also confirms known differences in subtypes of breast cancer but reveals a surprising finding in that basal-like breast cancers – also known as triple-negative breast cancer – are actually a class of their own. These cancers are very aggressive and more common in African-American and younger women.  Even though these basal-like cancers may arise in the breast, the study shows that at the molecular level they are more like ovarian cancers and cancers of squamous cell origin than other breast cancer subtypes.

Dr. Chris Benz, a professor at the Buck Institute for Research on Aging in Novato, CA, who is one of the authors of the study, commented: “Although follow-up studies are needed to validate and refine this newly proposed cancer classification system, it will ultimately provide the biologic foundation for that era of personalized cancer treatment that patients and clinicians eagerly await.”

Adapted from Medical News Today