First of all I want you to understand that thyroid cancers are not like other cancers in the head and neck are and have best prognosis among all cancers I think already treatment is done for your husband which usually includes thyroidectomy
and post operative radio iodine ablation. Chances of recurrence are very very minimal with 20 year survival rate of more than 90 percent
in other words very rarely we see patient of papillary carcinoma of thyroid dying because of papillary carcinoma of thyroid. So you need not worry and go for regular follow up as per your doctors instructions.