Saliva v. Cancer

While cancer of the lung has become much more prevalent in recent years, cancer of the mouth has not. Medical researchers have been puzzled by this, since cancer-causing agents, e.g., tobacco tar, reach the lungs through the mouth. In the Journal of the American Dental Association, investigators offer two tentative explanations: saliva has a protective effect, though whether this is brought about simply by washing away the cancer agent or by combating it chemically is not known; the tissues of the mouth are so constructed as to constitute a kind of "physiological barrier" against the entry of cancer agents.

Animal tests support both explanations. Mice develop skin cancer (which resembles lung cancer because of the similarity of the tissues) after a single painting of methylcholanthrene outside the mouth, but they resist repeated paintings inside. However, if their saliva glands are removed and the mouth becomes ulcerated, they become susceptible to cancer. These results are consistent with observed cases of human mouth cancer. Such cases are rare among both smokers and betel-nut chewers with good teeth. But they are relatively common in individuals with jagged teeth or ill-fitting dentures that may have worn through the "physiological barrier."

This file is automatically generated by a robot program, so reader's discretion is required.