A 45-year-old man came to a doctor complaining of a sore throat and fever that last for ten days. The patient has a history of ulcerative colitis, is a smoker, and has been smoking one pack of cigarettes per day for ten years. The patient's father died of cancer of the large intestine at the age of 50. Physical examination shows the following: body temperature-38.6 ° C, blood pressure-130/80 mm Hg, pulse- 72 / min., respiratory rate-18 / min. Examination of the oral cavity reveals erythematous pharynx and exudate in the tonsillar crypt. Antigen test for group A streptococcus was positive. What procedure that doctor can recommend for secondary prevention of cancer would be optimal for this patient?