New research partly led by UC San Francisco-affiliated 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. In the largest study of its kind to date, scientists analyzed molecular and genetic characteristics of more than 3,500 tumor samples of 12 different cancer types using multiple genomic technology platforms. Cancers traditionally have been categorized 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.
…Particularly striking results were seen 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. (In the new study, these squamous-cell cancers appeared to form their own subtype, whether they originated in the lungs or in the head and neck.) The findings may help explain why patients with bladder cancer “often respond very differently when treated with the same systemic therapy for their seemingly identical cancer type,” said Benz.