Spreading factor in human carcinomas.

'l'hc mechanisms responsible for the invasivencss of malignant tumors remain largely unknown. One explanation proposed is that malignant tumors may form a spreading factor that breaks down the barriers in surrounding normal tissues and thus permits penetration of tumor cells (6). If it exists, such a spreading factor would probably be hyaluronidasc which hydrolyses the connective tissue constituent hyaluronic acid (12). Since previous ~tudies (2,3,7) on hyaluronidase content of tumors have yielded indecisive results, and since improved methods are now available for assaying hyaluronidase, it seemed desirable to reinvestigate the problem. Specifically, experiments were designed to answer the question: is there evidence that human malignant tunmrs contain a spreading factor, such as hyaluronidase?