SIB-IMRT radiotherapy concomitant with cisplatin in locally advanced hypopharyngeal cancer: safety, feasibility

Abstract

Author(s): Lamiss Mohamed Sad*, Mohamed Barakat Khalil and Rasha Abd El-Ghany Khedr

Introduction: Radiotherapy is the main line of treatment of head and neck cancer including hypopharyngeal cancer either adjuvant/neoadjuvant radiotherapy or neoadjuvant/adjuvant concurrent chemoradiotherapy. The aim of radiotherapy is to provide maximum safe dose to organ at risk (healthy normal tissues). Studies had shown that the need to increase dose to the tumour was associated with great hazard to healthy normal tissues with induction of acute and late toxicity. The acute toxicity will result in treatment breaks and decreased local control due to repopulation of the tumour cells especially in head and neck cancer. Aim of the study: It was to reduce the radiation dose received by critical normal organs to allowed tolerance. Materials and methods: Twenty-two hypopharyngeal cancer patients either receiving radiotherapy as definitive therapy with concurrent cisplatin in dose of 40 mgm/m2 (group A) or adjuvant radiotherapy concurrent with same dose of cisplatin (group B). The closest critical organs of interest were the eye lens, parotid gland, submandibular salivary gland, oral mucosa, and thyroid gland. The patients were treated with Simultaneous Integrated Boost (SIB) (2 Gy to 2.21 Gy) Intensity Modulated Radiation Therapy (IMRT) with total dose of 66 -70 Gy, 5 fractions per week. Results: Response after definitive treatment with concurrent simultaneous boost were 5 out of elven cases 45.5% achieved pathological complete response. Median overall survival is 33 months with range from 14 month-36 month for the whole group, with 2-year overall survival 63.3% and 81.8% in definitive and adjuvant group respectively which was statistically insignificant (p=0.457). Two-year local control 90.9% versus 63.6% in adjuvant versus definitive treatment which was statistical significance (p=0.034). Two-year larynx preservation survival was 63.3%. As regard the homogeneity index and confirmatory index, they were per guidelines to decrease the dose to organ at risk. No more than grade 2 xerostomia was reported in both treatment arms. Conclusion: these results showed high local control with simultaneous integrated boost IMRT with reduced dose to organ at risk and it was complementary to other studies regarding the new era of modern radiation therapy techniques.

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