Smart (simultaneous modulated accelerated radiation therapy) boost: A new accelerated fractionation schedule for the treatment of head and neck cancer with intensity modulated radiotherapy

Purpose: To report the initial experience in the definitive treatment of he ad and neck carcinomas using SMART (Simultaneous Modulated Accelerated Radi ation Therapy) boost technique. Radiation was delivered via IMRT (Intensity Modulated Radiotherapy), The following parameters were evaluated: acute to xicity, initial tumor response, clinical feasibility, dosimetry and cost. Methods and Materials: Between January 1996 and December 1997, 20 patients with primary head and neck carcinomas were treated with SMART boost techniq ue. The treatment fields encompassed two simultaneous targets. The primary target included palpable and visible disease sites. The secondary target in cluded regions at risk for microscopic disease. Daily fractions of 2.4 Gy a nd 2 Gy were prescribed and delivered to the primary and secondary targets to a total dose of 60 Gy and 50 Gy, respectively. Lower neck nodes were tre ated with a single conventional anterior portal. This fractionation schedul e was completed in 5 weeks with 5 daily fractions weekly. Toxicity was eval uated by RTOG acute toxicity grading criteria, evidence of infection at imm obilization screw sites, subjective salivary function,weight loss, and the need for treatment split. Mean follow-up was 15.2 months. Initial tumor res ponse was assessed by clinical and radiographical examinations. Clinical fe asibility was evaluated by the criteria: time to treat patient, immobilizat ion, and treatment planning and QA time. In dosimetry, we evaluated the mea n doses of both targets and normal tissues and percent targets' volume belo w goal. To evaluate cost, Medicare allowable charge for SMART boost was com pared to those of conventional fractionated and accelerated radiotherapy. Results: Acute toxicity: None of the patients had a screw site infection an d all patients healed well after completion of radiotherapy. Sixteen of 20 patients (80%) completed the treatment within 40 days,without any split. Si xteen patients (80%) had RTOG Grade 3 mucositis while 10 patients (50%) had Grade 3 pharyngitis. Three of 20 patients (15%) had weight loss greater th an 10% of their pretreatment weight. Ten patients (50%) required intravenou s fluids, tube feeding or both. Nine patients (45%) reported moderate xeros tomia with significant relief reported within 6 months. Initial tumor respo nse: 19 patients (95%) had complete response (CR) while one had partial res ponse (PR). The patient with PR had stable disease on imaging at 12 months follow-up. Two patients were found to have lung metastases at 2 months and 5 months follow-up. To date, there have been two local recurrences in the c omplete responders. Both patients had nasopharyngeal primary; one was retre ated with radioactive Cesium-137 implant and the other died from the diseas e. Clinical feasibility: The average treatment time for a three-are treatme nt was 17.5 minutes and 2.5 minutes for each additional are. Eleven patient s (55%) had four-are treatment while six patients (30%) had five-are treatm ent and three patients (15%) had three-are treatment. Immobilization was re producible within less than 2 mm. The treatment planning, QA and documentat ion prior to treatment averaged 2 days. Dosimetry: The mean doses to the pr imary and secondary targets were 64.4 Gy and 54.4 Gy, respectively; 8.9% of the primary target volume and 11.6% of the secondary target volume were be low prescribed dose goal. The mean dose delivered to the mandible was 30 Gy , spinal cord 17 Gy, ipsilateral parotid 23 Gy, and contralateral parotid 2 1 Gy. Cost: Total Medicare allowable charge for SMART boost was $7000 compa red to $8600 (conventional) and $9400 (accelerated fractionation). Conclusions: SMART boost technique is an accelerated radiotherapy scheme th at can be delivered with acceptable toxicity. It allows parotid sparing as evidenced both clinically and by dosimetry. Initial tumor response has been encouraging. It is clinically feasible and cost saving. A larger populatio n of patients and a long-term follow-up are warranted to evaluate ultimate tumor control and late toxicity. (C) 1999 Elsevier Science Inc.