Rapid clinical progression of stage III-IV oral and oropharyngeal cancer after upfront surgery and difficulty in the assessment of the effectiveness of adjuvant radiotherapy

Introduction. Surgery with adjuvant radiation is the standard for treatment of advanced oral and oropharyngeal cancer. with the absence of randomized trials the assessment of the role of postoperative radiotherapy is difficult. Such assessments are usually based on retrospective analyses, whereas patient and tumor status during the time period between the operation and planned start of radiotherapy is not addressed.

The study objective is to assess the role of adjuvant radiotherapy in the treatment of stage III—IV oral and oropharyngeal cancer not associated with human papillomavirus with regard to rapid clinical disease progression after upfront surgical treatment.

Materials and methods. The case histories and outpatient records of 260 patients with oral and oropharyngeal cancer of stage III—IV, not associated with human papillomavirus, from 30 to 82 years old (average age - 56.52 years), operated in 2009-2018, were analyzed. Two groups of patients were identified. group 1 included 152 patients (58 %) irradiated postoperatively and group 2 consisted of 108 patients (42 %) treated surgically only. 22 patients of group 2 experienced rapid clinical disease progression, were deemed unsuitable for adjuvant treatment and formed group 2a. Comparison of the Kaplan-Meier overall survival and locoregional control was made for group 1 and the entire group 2 (formal analysis) and after exclusion from the latter patients of group 2a, based on the hypothesis of inability of radiotherapy to improve oncologic results in patients with such an unfavorable disease course.

Results. Mean follow up was 33.2 months (range 2-121 months). Locoregional control and 5 year overall survival were statistically higher in group 1: 70.4 % versus 45.4 % (р = 0.000) and 40.2 % versus 24.9 % (р = 0.000) that may imply a significant advantage of the combined over monomodal approach. After exclusion of group 2a patients from the analysis both differences considerably narrowed and were 70.4 % versus 55.8 % for locoregional control, 40.2 % versus 31.3 % for overall survival and became statistically insignificant (p = 0.067 and 0.111, respectively).

Conclusion. Rapid clinical disease progression in the time frame between surgical treatment and adjuvant radiotherapy is not a rare phenomenon with a very poor prognosis. It can be one of the reasons for postoperative treatment refusal. formal retrospective analyses of the role of adjuvant treatment without considering causes for its refusal may lead to the overestimation of the combined approach effectiveness.

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