A Forward Planning Intensity-Modulated Radiation Therapy with Simultaneous Integrated Boost in the Treatment of Head and Neck Cancer

Purpose: The aim of this study is to describe forward planning intensity-modulated radiation therapy (FP-IMRT) for the treatment of head-and-neck cancer and to confirm that in centers without the capabilities of inverse planning intensity- modulated radiation therapy (IP-IMRT) or in situations where patients are not ideal candidates for that technique, FP-IMRT can achieve a good dose distribution with sparing of parotid glands.Patient and Methods: Between June 2007 and April 2008, 19 patients with primary head-and-neck cancers were treated at King Abdul Aziz Hospital and Oncology Center Jeddah, using FP-IMRT techniques. In this study, thirty daily fractions over six weeks are used to simultaneously deliver 66Gy to the gross tumor (clinical target volume 1), 60Gy to the soft tissue and nodal regions adjacent to the previous volume (clinical target volume 2) and 54Gy to elective nodal regions (clinical target volume 3). These are biologically equivalent to 70, 60 and 50Gy, respectively, if given in 2Gy per fraction. The maximum dose to the brainstem and spinal cord are maintained below 54 and 50Gy, respectively. The mean dose to the parotid is maintained below 26Gy, or at least 50% of one of the parotid is to be maintained below 30Gy. All patients treated with a 7 gantry angles, with a total of 22 beams.Results: The aim of having at least 95% and 98% of the volume of CTV1 to receive at least 95% and 90% of the prescribed dose respectively was fulfilled in all cases, however only 75% of the patients met these criteria for CTV2 with an average of 92.8% of the volume received 95% of the dose and 97.3% of the volume received 90% of the dose. The maximum dose to the spinal cord was ranged from 39 to 50Gy (average 45. lGy). The mean dose of both parotid glands was kept below 26Gy in four patients and the other fifteen patients had at least one parotid gland with a mean dose below 26Gy.Conclusion: FP-IMRT allows the delivery of a high dose to the target while minimizing the normal tissue toxicity. In a center without the capabilities of IP-IMRT or in situations where patients are not ideal candidates for that technique, FP- IMRT can achieve a good dose distribution.