Colon Cancer Prognosis and Survival

The prognosis of colon cancer is related to the stage of disease at diagnosis, histologic differentiation, lymphatic invasion, and extent of tumor-free surgical resection margins. Molecular genetic markers may define subsets of patients either more or less likely to develop tumor recurrence and lead to more rational application of adjuvant multimodality treatment.Definition of subpopulations of cells in the primary tumor that have a particular predisposition to metastasize to particular sites also has exciting potential for use in the near future.

Numerous staging schemes have been defined based on the depth of bowel wall penetration by tumor and lymph node involvement. Most, however, are derived from either the original classification reported by Dukes in 1932 or the TNM staging classification originally applied by the International Union Against Cancer (UICC) in 1978 and adopted by the American Joint Committee on Cancer (AJCC) in 1982. The unified AJCC/UICC TNM staging system was updated in 1997 and is listed in Table 16-6 and illustrated along with the most widely used modified Dukes classification in Figure 16-5 . The influence of disease stages on prognosis of colon and rectal cancer is depicted in Table 16-7 . Other pathologic features, in addition to bowel wall penetration and lymph node status, that have been demonstrated to predict outcome are listed in Table 16-8 . In contrast to many other solid tumors, prognosis in patients with colorectal cancer is not influenced by the size of the primary lesion if data are corrected for nodal involvement and histologic differentiation. In fact, an inverse relationship between size and prognosis may exist.