[Cancer of the rectum: distal intramural spread is correlated with lymph node involvement]

Cancers of the rectum are only rarely associated with distal intraparietal microscopic extension situated below the apparent pole of the tumour. When such extension exists, it may be either limited to several millimetres and is generally continuous with the tumour, or it may be extensive and composed of tumour lesions separated from the principal lesion by healthy tissue. On 119 rectal resection specimens for cancer, distal intraparietal extension was found to be significantly correlated with the degree and multiplicity of lymph node involvement. Tumours without distal intramural extension were associated with lymph node invasion in only 20% of cases and half of them were multiple involvements. In contrast, the frequency of lymph node invasion in cases of distal intramural extension was 80% with multiple node involvement in every case. In cases of distal intraparietal invasion, immuno-histochemical techniques demonstrated tumour emboli in the vessels and lymphatics. In cases of the rectum, lymph node invasion and its multiplicity are directly related to the presence of distal intraparietal invasion.