Radical radiation therapy in oropharyngeal malignancies have a significant toxicity especially in relation to dose to dysphagia aspiration related structures (DARS), mucositis and aspiration which leads to prolonged overall treatment times, thereby, having an impact on survival outcomes. Interstitial Brachytherapy (ISBT) has significant role in reducing these toxicities, however, literature comparing Intensity modulated radiation therapy (IMRT) with Brachytherapy boost is lacking. Our study looks in to the clinical outcomes and toxicity profile while comparing the two treatment modalities.
Materials and Methods:
A total of 70 patients diagnosed histopathologically as squamous carcinoma of oropharynx were randomized to receive radical radiation therapy with IMRT (n=35) or IMRT with ISBT boost (n=35). The total dose with IMRT was 70Gy and in ISBT, initial dose was 50Gy with IMRT followed by 24.5Gy dose (3.5Gy in 12 fractions). Patients were followed up as per institute protocol and assessed for a median follow-up of 36 months. Assessment of survival outcomes in terms of progression free survival (PFS) and overall survival (OS) were assessed. Toxicity profile was assessed as per CTCAE 4.0 criteria and quality of life was assessed as per EORTC-C30 and HN35 questionnaires. Dosimetric parameters for the target volumes were compared along with assessment of various important organs at risk (OAR).
After a median follow up of 36 months, PFS was 86% vs 81% favoring ISBT arm (p=0.032), however, there was no difference in overall survival. On assessment of toxicities, dysphagia and xerostomia were significantly reduced with ISBT boost with Grade II and III toxicities 12% and 18% vs 18% and 24% respectively. On QoL assessment, physical (p<0.001) and social functioning (p=0.012) favored ISBT boost. On symptom assessment, fatigue, dyspnea, appetite loss, speech problems, swallowing and pain was significantly reduced with ISBT boost. Dosimetric parameters showed significant dose reduction to DARS (p<0.001) and parotid glands (p<0.001) with ISBT boost.
ISBT boost has shown to be effective in improving PFS, toxicity profile and quality of life outcomes in oropharyngeal malignancies in spite of technological advancements in form of IMRT. ISBT should be employed in treatment armamentarium to dose escalate and thereby improve survival especially in oropharyngeal malignancies.
Dr Vibhay Pareek –I am a Senior Resident at National Cancer Institute, AIIMS, New Delhi, India and an ardent student of Brachytherapy besides the other aspects of Radiation Oncology. My interests in Brachytherapy include Head and Nek, Breast and Sarcoma interstitial Brachytherapy and Intracavitary Brachytherapy and have a few publications related to the same. I had the opportunity to work under the mentorship of Dr. Rajendra Bhalavat who is considered to be among the pioneers of brachytherapy in my country.