Scientists suggests that one in 10 cancer patients would be more accurately diagnosed if their tumors were defined by cellular and molecular criteria rather than by the tissues in which they originated, and that this information, in turn, could lead to more appropriate treatments.
The study was conducted as part of The Cancer Genome Atlas (TCGA) initiative spearheaded by the National Cancer Institute and National Human Genome Research Institute, both part of the National Institutes of Health.
Cancers traditionally have been categorised by their "tissue of origin" such as breast, bladder, or kidney cancer. But tissues are composed of different types of cells, and the new work indicates that in many cases the type of cell affected by cancer may be a more useful guide to treatment than the tissue in which a tumor originates.
Striking results were seen particularly in bladder and breast cancers. At least three different subtypes of bladder cancer were identified, one virtually indistinguishable from lung adenocarcinomas, and another most similar to squamous-cell cancers of the head and neck and of the lungs.
Christopher Benz, professor at the Buck Institute for Research on Aging, said that this genomic study not only challenged the existing system of classifying cancers based on tissue type, but also provided 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.
He further added that the findings might help explain why patients with bladder cancer often respond very differently when treated with the same systemic therapy for their seemingly identical cancer type.
The study would fuel clinical trial designs based on genomic reclassification of tumors whereby patients become eligible for novel therapeutics. Although follow-up studies are needed to validate and refine this newly proposed cancer classification system and it would ultimately provide the biologic foundation for that era of personalised cancer treatment that patients and clinicians eagerly wait.
The study is published in the online edition of Cell.