Abstract
PurposeWe evaluated the efficiency and toxicity of stereotactic hypofractionated boost in combination with conventionally fractionated radiotherapy in the treatment of advanced floor of the mouth cancer.MethodsThirty-seven patients with advanced stage of the floor of the mouth cancer, histologically confirmed squamous cell carcinoma (p16 negative) ineligible for surgical treatment, were indicated for radiochemotherapy or hyperfractionated accelerated radiotherapy (HART). The radiotherapy protocol combined external beam radiotherapy (EBRT) and a stereotactic hypofractionated boost to the primary tumor. The dose delivered from EBRT was 70–72.5 Gy in 35/50 fractions. The hypofractionated boost followed with 10 Gy in two fractions. For the variables—tumor volume, stage and grade a multivariate analysis was performed to find the relationship between overall survival, local progression and metastasis. Toxicity was evaluated according to CTCAE scale version 4.ResultsAfter a median follow-up of 16 months, 23 patients (62%) achieved complete remission. The median time to local progression and metastasis was 7 months. Local control (LC) at 2 and 5-years was 70% and 62%, respectively. Progression-free survival (PFS) and overall survival (OS) were 57% and 49% at 2 years and 41% and 27% at 5 years, respectively. Statistical analysis revealed that larger tumors had worse overall survival and a greater chance of metastasis. Log-Rank GTV > 44 ccm (HR = 1.96; [95% CI (0.87; 4.38)]; p = 0.11). No boost-related severe acute toxicity was observed. Late osteonecrosis was observed in 3 patients (8%).ConclusionThe combination of EBRT and stereotactic hypofractionated boost is safe and seems to be an effective option for dose escalation in patients with advanced floor of the mouth tumors who are ineligible for surgical treatment and require a non-invasive approach.
Highlights
Tumors of the floor of the mouth represent approximately 28% of oral cavity tumors [1], and many of them are presented in advanced stages of disease at the timeBlažek et al Radiat Oncol (2021) 16:122 the majority of local failures are identified in high-dose areas of modern radiochemotherapy due to the presence of a subpopulation of cells resistant to the standard radiation dose
The stereotactic boost did not increase the incidence of higher acute radiation toxicity and all cases recovered within 12 weeks after completing treatment
Late radiation toxicity manifested as osteonecrosis and dysphagia
Summary
Tumors of the floor of the mouth represent approximately 28% of oral cavity tumors [1], and many of them are presented in advanced stages of disease at the timeBlažek et al Radiat Oncol (2021) 16:122 the majority of local failures are identified in high-dose areas of modern radiochemotherapy due to the presence of a subpopulation of cells resistant to the standard radiation dose. Technological and technical improvements during the last years allowed for significant advances in the field of radiation therapy of head and neck cancer. The adoption of intensity-modulated radiation therapy and the use of multimodality imaging for tumor volume definition and organ at risk delineation have improved the clinical outcomes of patients with head and neck tumors [14]. Brachytherapy in combination with external beam radiotherapy (EBRT) and chemotherapy is an effective technique that leads to local dose escalation over the possibilities of up-to-date EBRT technologies [15, 16]. Have been published studies with stereotactic dose escalation in patients with oropharyngeal carcinomas [17, 18]. We present our experience with stereotactic hypofractionated radiotherapy boost combined with conventionally fractionated radiotherapy in the treatment of advanced floor of the mouth tumour
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