Which factor is commonly associated with malignant neoplasm of the mouth?

• A. Low-sodium diet.
• B. Chronic hydration.
• C. Oral tobacco use.
• D. Regular vigorous chewing of gum.

Answer: (C)

Oral cancer is most strongly linked to tobacco exposure. The carcinogens in tobacco products—whether smoked or smokeless—directly affect the cells lining the mouth, causing DNA mutations that can start the sequence from dysplasia to carcinoma. Smokeless tobacco, in particular, can produce local lesions like leukoplakia that may progress to cancer, and the risk rises with duration and intensity of use. Alcohol adds another layer of risk and can amplify the effect when combined with tobacco.

The other options don’t fit as risk factors for mouth cancer: they don’t expose the oral mucosa to carcinogens or cause the local mucosal changes that lead to malignant transformation, whereas tobacco use does.