External radiation to the neck for cancer of the larynx is most likely to cause which short-term side effect?

• A. Dyspnea
• B. Diarrhea
• C. Sore throat
• D. Constipation

Answer: (C)

Exposure of the throat and surrounding mucosa to external beam radiation commonly causes acute irritation of the mucous membranes. The rapidly dividing cells lining the pharynx and larynx are particularly susceptible, leading to mucositis and inflammation that manifest as a sore throat, especially with swallowing. This is one of the most frequent early side effects when treating cancers in the neck region.

Diarrhea and constipation are more typical of radiation fields that involve the gut, not the neck area, and dyspnea is less likely to be an immediate, direct mucosal reaction in this context. So the sore throat best fits the common short‑term mucosal reaction to neck irradiation.