Desmoplasia is thought to have a number of underlying causes. In the reactive stroma hypothesis, tumor cells cause the proliferation of fibroblasts and subsequent secretion of collagen.[3] The newly secreted collagen is similar to that of collagen in scar formation – acting as a scaffold for infiltration of cells to the site of injury.[12] Furthermore, the cancer cells secrete matrix degrading enzymes to destroy normal tissue ECM thereby promoting growth and invasiveness of the tumor.[3] Cancer associated with a reactive stroma is typically diagnostic of poor prognosis.[3]