A patient treated with radiation for PROSTATE cancer two years ago now presents with rampant cervical caries. Which of the following is NOT a plausible cause?

Correct answer: B. The radiation field, which did not include the salivary glands

• A. Many medications used during and after cancer treatment — antiemetics, opioids, antidepressants, anticholinergics — cause xerostomia, and this is an entirely plausible contributor.
• B. CORRECT — this is the implausible cause. Radiation caries requires irradiation of the SALIVARY GLANDS, which happens with head and neck fields. A pelvic field for prostate cancer does not reach the salivary glands and therefore cannot produce radiation-induced xerostomia or radiation caries.
• C. Fatigue, nausea and mucosal discomfort routinely compromise oral hygiene during cancer treatment.
• D. Nutritional supplements, sugary drinks and frequent small carbohydrate intake to maintain weight during illness are a well-recognized cause of rampant caries in cancer patients.

Note: The distinguishing question for radiation caries is always ANATOMICAL: was the salivary gland in the field? Head and neck radiation over about 30 Gy to the parotid produces permanent hyposalivation and the characteristic circumferential cervical and cusp-tip caries. Radiation elsewhere in the body does not.