Tumor size and regional lymph node metastasis in colorectal cancer. A preliminary analysis from the NSABP clinical trials.

This study explores the relationships between tumor size and regional lymph node involvement in patients with Dukes' B and C colorectal cancer in the randomized prospective clinical trials of the NSABP. Six-hundred and seventy patients with colon cancer and 236 patients with carcinoma of the rectum were available for analysis. Utilizing cumulative frequency distributions of tumor diameter and tumor volume, comparisons were carried out between Dukes' B and C lesions. The results indicate that there was no correlation between the longest diameter of the primary tumor and the status of regional lymph nodes for either colon or rectal cancer. Moreover, this lack of association was evident throughout the distribution. When tumor volume was analyzed, Dukes' B tumors proved to be consistently larger than Dukes' C lesions. This inverse relationship was statistically significant for carcinoma of the rectum. These findings underscore the unique biological behavior of colorectal cancer and emphasize the function of the current generation of randomized prospective trials in providing natural history information.