Rationale: Cancer of the tongue causes difficulty swallowing due to enlarged lymph nodes in the neck. Sores that bleed or do not heal over time are another sign of tongue cancer. Chewing may be difficult or painful for clients with cancer of the tongue. Weight loss, not weight gain, can occur due to difficulty chewing and swallowing. Poor-fitting dentures or loose teeth are another sign. A black, hairy tongue is caused by overgrowth of yeast and bacteria and is a benign condition unrelated to cancer of the tongue.