Enkephalins in large bowel malignancy and in acute appendicitis.

Leucine and methionine enkephalins were measured by biological assay in normal colon, adenocarcinoma of the colon, carcinoma of the caecum, and in normal and inflamed appendix. Methionine enkephalin levels in both the adenocarcinomas and inflamed appendices were significantly higher than in normal controls. No significant change occurred in leucine enkephalin levels. The caecal tumours were anaplastic and contained no demonstrable opioid activity.