Purpose: To report on the tumor control, adverse late normal tissue sequelae, and functional performance in patients with tonsillar fossa and/or soft palate (SP) tumors. The aim of the study is to validate the use of a more selective clinical target volume in conjunction with highly conformal radiotherapy (RT) techniques to better spare the surrounding normal tissues.
Methods and materials: Between 1986 and 2001, T1-T3 tonsillar fossa/SP tumors were treated in the Erasmus Medical Center using external beam radiotherapy (EBRT) to 46 Gy in 2-Gy fractions to the primary tumor and neck, followed by brachytherapy (BT) to the primary. Neck dissection was performed for node-positive disease (BT group; 104 patients). If BT was not feasible, patients underwent surgery and postoperative RT (PORT) to a dose of 50-70 Gy in 2-Gy fractions (surgery group; 86 patients). Local control, regional control, disease-free survival, and overall survival were determined. Late side effects were scored using the Radiation Therapy Oncology Group criteria. Univariate and multivariate Cox regression analyses were performed for regional failure (RF), with the parameters gender, age, site, TN stage, modality, dose, and overall treatment time. Recurrences in the contralateral neck were also related to significant ipsilateral involvement of the base of tongue and/or involvement of the SP crossing the midline. To determine the performance status scale scores and degree of xerostomia, a survey was conducted among patients living with no evidence of disease and a minimum of 2 years of follow-up. For that purpose, a research nurse interviewed patients regarding eating in public, normalcy of diet, normalcy of speech, and xerostomia.
Results: The tumor control rates after BT vs. surgery at 5 years were 88% vs. 88% for local control; 93% vs. 85% for regional control; 57% vs. 52% for disease-free survival; 67% vs. 57% for overall survival; and 5% vs. 6% for RF. No patient had RF in the contralateral untreated N0 neck (0 of 14 vs. 0 of 15). Multivariate Cox regression analysis for RF was statistically significant for Stage T2 vs. T3 (hazard ratio 0.09) and for the dose to the neck >46 Gy (hazard ratio, 8.7; 95% confidence interval, 1.3-57.1). The significant late side effects in the BT group vs. surgery group were ulcer in 39% vs. 7% (p = 0.001) and trismus in 1% vs. 21% (p = 0.005). The performance status scale scores and response to questions regarding xerostomia for BT vs. surgery revealed no statistically significant differences for eating in public, normalcy of diet, normalcy of speech, and xerostomia. The mean visual analog score for xerostomia was 5.5 in the BT group vs. 6 in the surgery group.
Conclusion: Excellent locoregional control was obtained in T1-T3 tonsillar fossa and/or SP tumors. The rate at 10 years was 84% (BT group) vs. 78% (surgery group). However, adverse late side effects were not negligible. In addition to modality-specific side effects (ulcer/trismus), both treatment groups were significantly affected by xerostomia. Only 6 recurrences (4%) were observed in the 149 electively treated contralateral necks, and no relapses were seen in the 29 untreated contralateral necks. We, therefore, suggest that it is not necessary to treat the contralateral neck, unless the tumor extends beyond the midline of the soft palate (uvula) or beyond the lateral one-third of the ipsilateral base of the tongue. Moreover, with the currently available CT-based neck level definitions, more conformal contours (i.e., tighter boundaries) around the clinical target volume can be designed. In this way, critical structures such as the temporomandibular joint and part of the pterygoid muscles can be avoided more easily. Also, when using highly conformal treatment techniques (e.g., intensity-modulated RT), one can further reduce the dose to the major salivary glands and oral mucosa. We believe these measures will lead to less trismus and less xerostomia.