Staging of carcinoma of the colon and rectum.

Commonly used modifications of the Dukes' system for staging carcinomas of the colon and rectum are inaccurately presented in many current textbooks and articles. These modifications divide Dukes' Stage B category into B1 and B2, depending upon whether or not the lesion has invaded or penetrated the muscularis propria. The term muscularis propria has been incorrectly interpreted to mean muscularis mucosa; as a result, A, B1 and B2 lesions, according to the modified systems all correspond to Dukes' Stage A category, and there is no modified stage corresponding to Dukes' Stage B. It is suggested that the term "modified Dukes" be discarded and that modified systems be given the eponyms of their describers. If the modified systems are to be continued, they must be correctly understood and presented. The simple and unambiguous nature of the original Dukes' system, however, favors its widespread use.