According to the journal Cancer, patients who have radiation for head and neck cancers, either with or without chemotherapy, are more likely than typically known to develop hypothyroidism, or an underactive thyroid.

According to the researchers, routine thyroid screening should be conducted after treatment for head and neck cancers.

Among the patient studied, within five-years, 48 percent had developed hypothyroidism, and within eight years, the projected rate was 67 percent. The median time from treatment to development of hypothyroidism was approximately 17 months.

Source: "Hypothyroidism: A frequent event after radiotherapy and after radiotherapy with chemotherapy for patients with head and neck carcinoma," Cancer 2001;92:2892-2897