Post-treatment follow-up of head and neck cancer patients is crucial due to their high risk of disease recurrence and increased likelihood of developing secondary cancers. Rehabilitation requires multiple visits to different healthcare professionals and addressing challenges with eating, speaking, breathing, and cosmetic concerns caused by treatments. As the number of these cases continues to rise, additional resources are needed for adequate monitoring.

This thesis aimed to investigate the appropriate duration of routine follow-up, the significance of PET imaging at the 1-year mark after treatment completion, the use of telemedicine in surveillance, and the long-term effects of head and neck cancer treatments. The research data included all head and neck cancer patients treated at Turku University Hospital between 1999 and 2008 (I), those under surveillance for head and neck cancer between 23 March and 27 May 2020 (II), patients who received radiation therapy for head and neck cancer between 2010 and 2015 (III), and head and neck cancer patients treated at Turku University Hospital and Tampere University Hospital between 2010 and 2015 (IV).

We found that routine 3-year follow-up was sufficient for head and neck cancers. However, patients should have the opportunity to contact healthcare providers in case of new symptoms even after this period, to promptly arrange appointments and necessary additional examinations (I). After the first year of surveillance, some follow-ups could potentially be conducted by phone without delaying the detectionof disease recurrence (II). Difficulty in swallowing and hypothyroidism were the most common of the studied long-term side effects of radiation therapy. The dose of radiation to the neck did not appear to influence the occurrence of side effects. Osteoradionecrosis was observed only in patients with oral cavity cancer (III). Routine PET imaging at the 1-year mark after treatment completion did not improve the 5-year prognosis of the whole imaged patient group or of any particular subgroup (IV).