A Prospective Observational Study to Compare the Effect of Adaptive Radiation Therapy in Head and Neck Cancer Patients Treated with Helical Tomotherapy – Bangalore, Karnataka

BACKGROUND Establishing the usefulness of adaptive radiotherapy in our setting with limited data might help to ensure better conformity and reduce treatment related morbidity. Hence we conducted this study to elicit the benefit of adaptive radiotherapy with helical tomotherapy. METHODS This is a prospective study conducted among 25 head and neck cancer patients undergoing radiotherapy with helical tomotherapy. All patients underwent initial radiation therapy treatment planning simulation positron emission tomography computed tomography (PET CT/ CT scan) [CT-1], followed by repeat PET CT/ CT scan at 4th - 5th week of radiotherapy [CT-2]. Planning for full intended dose [66 Gy - 70 Gy] was done on both the scans, keeping the radiation therapy planning parameters same. Changes in the volume of the clinical target volumes (CTV), changes in the volume and dose to spinal cord, bilateral parotids, and mandible were compared. A p - value of < 0.05 was considered for statistical significance. RESULTS A significant reduction in the volumes of tumour - CTV-1 [CT-1 v/s CT-2: 166.82 cc v/s. 150.63 cc] and of lymph nodal region - CTV-2 [CT-1 v/s CT-2: 260.29 cc v/s 228.00 cc], contra lateral parotid gland [CT-1 v/s CT-2: 33.00 cc v/s 18.72 cc] were observed (P < 0.05). The mean doses received by contra lateral parotid gland [CT-1 v/s. CT-2: 23.14 Gy v/s 21.26 Gy] were significantly lesser in the CT2 scans (P < 0.05). The mean maximum doses were also significantly lesser to the mandible and spinal cord i.e., CT-1 v/s. CT-2: 68.528 Gy v/s 67.39 Gy and 39.45 Gy v/s. 37.33 Gy respectively (P < 0.05). A significant reduction in standardised uptake value (SUV), values of the primary tumour and involved lymph nodes was observed between CT-1 and CT-2. CONCLUSIONS During 4th to 5th week of radiation therapy, significant reductions in the CTVs and in dose to OARs were noted. Thus, we recommend at least one re-simulation scan and re-planning during radiation therapy, irrespective of the type of technique of radiation therapy. KEYWORDS Adaptive Radiation Therapy, IMRT, Tomotherapy

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Reducing Xerostomia by Comprehensive Protection of Salivary Glands in Intensity-Modulated Radiation Therapy with Helical Tomotherapy Technique for Head-and-Neck Cancer Patients: A Prospective Observational Study

BioMed Research International ◽

10.1155/2019/2401743 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9

Author(s):

Feng Teng ◽

Wenjun Fan ◽

Yanrong Luo ◽

Zhongjian Ju ◽

Hanshun Gong ◽

...

Keyword(s):

Radiation Therapy ◽

Head And Neck Cancer ◽

Head And Neck ◽

Salivary Glands ◽

Cancer Patients ◽

Neck Cancer ◽

Helical Tomotherapy ◽

Clinical Stage ◽

Flow Rates ◽

Saliva Flow

Objective. This study aimed to analyze the effects of comprehensive protection of bilateral parotid glands (PG-T), contralateral submandibular gland (cSMG), and accessory salivary glands in the oral cavity (OC) by helical tomotherapy for head-and-neck cancer patients. Methods. Totally 175 patients with histologically confirmed head-and-neck cancer treated with helical tomotherapy were recruited. The doses delivered to PG-T, cSMG, and OC were constrained to be as low as possible in treatment planning. The saliva flow rates and xerostomia questionnaire were evaluated. Correlation between xerostomia and other clinical factors were assessed using univariate and multivariate models. The impact of salivary gland dose on locoregional (LR) recurrence was assessed by Cox analysis. ROC curve was used to determine the threshold of mean dose for each gland. Results. The median follow-up was 25 (19–36) months. The OC mean dose, PG-T mean dose, cSMG mean dose, age, clinical stage (II and III versus IV), and both unstimulated and stimulated saliva flow rates were significantly correlated with xerostomia. The OC mean dose, cSMG mean dose, age, and clinical stage were predictors of xerostomia after adjusting PG-T mean dose, and unstimulated and stimulated saliva flow rates. Xerostomia was significantly decreased when the mean doses of PG-T, cSMG, and OC were kept below 29.12Gy, 29.29Gy, and 31.44Gy, respectively. At 18 months after radiation therapy, early LR recurrence rate was only 4%. Conclusion. Comprehensive protection of salivary glands minimized xerostomia in head-and-neck cancer patients treated by helical tomotherapy, without increasing early LR recurrence risk.

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