Critical remarks on the role of collagenolytic enzymes in carcinomas of the head and neck.

Collagenolytic activity of eight squamous cell carcinomas of the head and neck as well as xenografts of such tumors in nude mice was investigated by two different methods. High enzyme activities seem to be present in necrotic tumor areas, whereas the germinative zones tend to show lower collagenase levels. There is experimental evidence for the assumption of a collagen-stabilizing factor (CSF). A hypothetic concept including the results of other authors is developed concerning the role of collagenase in infiltrative growth of malignant tumors. The greater part of these questions being unanswered, further studies on collagenolytic activity in malignancy will be necessary.