Session Item

The assessment schedule after definitive loco-regional treatment for head and neck cancer (HNC) is determined arbitrarily in daily clinical practice. Here, we propose the optimal assessment schedule for each subgroup stratified by subsites and HPV status in HNC using a parametric model of standardized event-free survival (EFS) curves.

A total of 673 patients with locally advanced stage HNC (227 nasopharynx (NPC), 237 HPV-positive oropharynx (HPV+ OPC), 47 HPV-negative oropharynx (HPV- OPC), 97 larynx (LC), and 65 hypopharynx cancer (HPC)) and 113 patients with early-stage larynx cancer (ELC) who completed definitive loco-regional treatment at two tertiary referral university hospitals between 2008 and 2019 were retrospectively analyzed. EFS was defined as the period from the end of treatment to the date of any event (tumor recurrence or secondary malignancies). EFS curves were estimated using the piecewise exponential survival model. The criterion of a 5% event rate among the remaining patients at each observation period was used to determine the optimal assessment time point. The benefit from the optimal schedule was measured for the comparison with the institutional policy, which followed-up every two months for the first year, every three months for the following two years, and every 6-12 months thereafter.

With a median follow-up of 57.8 months (range, 6.4 -158.1), the event rates of NPC, HPV+ OPC, HPV- OPC, LC, HPC, and ELC were 18.9%, 15.2%, 36.2%, 30.9%, 44.6%, and 13.3% respectively. The optimal follow-up intervals for HPC/LC/NPC were every 1.9/3.0/5.5 months until 16.5 months after treatment, every 3.7/5.8/10.6 months from 16.5 to 25 months, every 9.0/14.2/26.0 months from 25 to 99 months, and open follow-up thereafter. For HPV- OPC, surveillance every 2.5 months until 16.5 months after treatment, every 4.9 months from 16.5 to 25 months, every 12.1 months from 25 to 99 months are recommended. In contrast, for HPV+OPC, optimal intervals were every 7.1 months until 16.5 months after treatment, every 13.7 months from 16.5 to 25 months, every 33.5 months from 25 to 99 months. Regarding surveillance of distant events, the optimal follow-up intervals were much longer: for HPC/LC/NPC, every 5.6/7.8/12.5 months until 27.5 months after treatment, every 15.9/22.0/35.4 months from 27.5 to 99 months and open follow-up thereafter; for HPV- OPC/HPV+ OPC, every 6.6/18.8 months until 27.5 months after treatment, every 18.8/53.2 months from 27.5 to 99 months and open follow-up thereafter. The proposed schedule could save an average of 11 outpatient visits and 1,481,590 won per person compared to the previous routine schedule.

The optimal assessment schedule for HNC layered by subsites and HPV status can be reasonably determined using parametric modeling of EFS. Due to the limited healthcare resource and an increasing number of HNC patients, this evidence-based assessment model will be worthwhile.