Rick Davis

Effectiveness of image-guided radiotherapy for laryngeal sparing in head and neck cancer

We would like to compare the effectiveness of image-guided (IGRT) and intensity-modulated (IMRT) radiotherapy to spare the larynx in head and neck cancer patients. A retrospective review of 48 patients undergoing radiation for non-laryngeal and non-hypopharyngeal head and neck cancers. Mean laryngeal and hypopharyngeal dose was compared between 11 patients treated with IMRT and 37 patients treated with IGRT. Mean laryngeal dose was, respectively, 41.2 Gy and 22.8 Gy for the IMRT and IGRT technique (p<0.001). The radiation dose to the middle and inferior pharyngeal muscles was also significantly reduced with the IGRT technique. Mean pharyngeal dose was, respectively, 52 Gy and 26 Gy for the IMRT and IGRT technique (p=0.0001). Laryngeal sparing IGRT technique for head and neck cancer minimizes radiotherapy dose to the larynx and pharynx without sacrificing target coverage, even in the presence of neck lymph nodes.

Feasibility of Tomotherapy to spare the cochlea from excessive radiation in head and neck cancer

We would like to evaluate the effectiveness of Tomotherapy for decreasing radiation dose to the cochlea in head and neck cancer patients. A retrospective review of 72 patients undergoing radiation for head and neck cancer was performed. Cochlea dose was compared between 20 patients treated with conventional intensity modulated radiotherapy (IMRT) and 52 treated with Tomotherapy. A review of literature was performed to assess cochlea dose reported with the IMRT technique for head and neck cancer. Mean total cochlea dose was 36 Gy for IMRT compared to 12.1 Gy for Tomotherapy (p=0.002). Mean right cochlea dose was respectively, 16.6 and 6.2 Gy for IMRT and Tomotherapy (p=0.007), and 19.3 and 5.9 Gy for the left. Cochlea (p=0.002). Mean cochlea dose reported in the literature ranged from 16 to 55 Gy with IMRT for head and neck cancer. Helical Tomotherapy for head and neck cancer may significantly decrease radiation dose to the cochlea without sacrificing target volume coverage.

Feasibility of tomotherapy to reduce normal lung and cardiac toxicity for distal esophageal cancer compared to three-dimensional radiotherapy

PURPOSE To compare the effectiveness of tomotherapy and three-dimensional (3D) conformal radiotherapy to spare normal critical structures (spinal cord, lungs, and ventricles) from excessive radiation in patients with distal esophageal cancers. MATERIALS AND METHODS A retrospective dosimetric study of nine patients who had advanced gastro-esophageal (GE) junction cancer (7) or thoracic esophageal cancer (2) extending into the distal esophagus. Two plans were created for each of the patients. A three-dimensional plan was constructed with either three (anteroposterior, right posterior oblique, and left posterior oblique) or four (right anterior oblique, left anterior oblique, right posterior oblique, and left posterior oblique) fields. The second plan was for tomotherapy. Doses were 45 Gy to the PTV with an integrated boost of 5 Gy for tomotherapy. RESULTS Mean lung dose was respectively 7.4 and 11.8 Gy (p=0.004) for tomotherapy and 3D plans. Corresponding values were 12.4 and 18.3 Gy (p=0.006) for cardiac ventricles. Maximum spinal cord dose was respectively 31.3 and 37.4 Gy (p < 0.007) for tomotherapy and 3D plans. Homogeneity index was two for both groups. CONCLUSIONS Compared to 3D conformal radiotherapy, tomotherapy decreased significantly the amount of normal tissue irradiated and may reduce treatment toxicity for possible dose escalation in future prospective studies.

Effectiveness of intensity-modulated and image-guided radiotherapy to spare the mandible from excessive radiation

We would like to assess the effectiveness of intensity-modulated radiotherapy (IMRT) or image-guided radiotherapy (IGRT) to decrease the risk of osteoradionecrosis in locally advanced head and neck cancer. We conducted a retrospective study of 83 patients with head and neck cancer undergoing concurrent definitive chemoradiation, post-operative radiotherapy or chemoradiation, or radiotherapy alone with IMRT or IGRT. Mean mandibular dose was, respectively, 43.6Gy and 43.8Gy for the IMRT and IGRT technique. At a median follow-up of 28 months (5-55 months), only one patient developed osteoradionecrosis requiring hyperbaric oxygen. Sharp dose falloff associated with IMRT and IGRT decreased excessive radiation of the mandible and may reduce the risks of osteoradionecrosis.

Feasibility of Intensity-Modulated and Image-Guided Radiotherapy for Functional Organ Preservation in Locally Advanced Laryngeal Cancer

Purpose The study aims to assess the feasibility of intensity-modulated and image-guided radiotherapy (IMRT, and IGRT, respectively) for functional preservation in locally advanced laryngeal cancer. A retrospective review of 27 patients undergoing concurrent chemoradiation for locally advanced laryngeal cancers (8 IMRT, 19 IGRT) was undertaken. In addition to regular clinical examinations, all patients had PET imaging at 4 months and 10 months after radiotherapy, then yearly. Loco-regional control, speech quality and feeding-tube dependency were assessed during follow-up visits. Results At a median follow-up of 20 months (range 6–57 months), four out of 27 patients (14.8%) developed local recurrence and underwent salvage total laryngectomy. One patient developed distant metastases following salvage surgery. Among the 23 patients who conserved their larynx with no sign of recurrence at last follow-up, 22 (95%) reported normal or near normal voice quality, allowing them to communicate adequately. Four patients (14.8%) had long-term tube feeding-dependency because of severe dysphagia (2 patients) and chronic aspiration (2 patients, with ensuing death from aspiration pneumonia in one patient). Conclusions and Clinical Relevance Functional laryngeal preservation is feasible with IMRT and IGRT for locally advanced laryngeal cancer. However, dysphagia and aspiration remain serious complications, due most likely to high radiation dose delivery to the pharyngeal musculatures.

Impact of image-guided radiotherapy to reduce laryngeal edema following treatment for non-laryngeal and non-hypopharyngeal head and neck cancers

We would like to determine the effectiveness of image-guided radiotherapy (IGRT) to reduce laryngeal edema following treatment for head and neck cancer and to assess patient perception of voice and speech after treatment. We conducted a retrospective review of 44 patients undergoing radiation for non-laryngeal and non-hypopharyngeal head and neck cancers. Endoscopic and/or mirror examinations of the larynx were performed following radiotherapy at each follow-up visit. Laryngeal edema was assessed based on the Radiation Therapy Oncology Group grading scale. Patients were also asked to rate about the voice and speech quality relative to their pre-radiotherapy status. The mean laryngeal dose was 16.3 Gy (range: 11.7-45.5 Gy). At a median follow-up of 14 months (range: 2-31 months), three patients (7%) developed laryngeal edema (one grade 1, two grade 2). The mean laryngeal dose was respectively 20.3 Gy in two patients and 20.7 Gy in the third patient developing laryngeal edema. Except for one patient who continued to smoke and drink after radiotherapy, no patient reported any significant change in voice and speech quality after treatment. IGRT results in low rates and low severity of laryngeal edema following treatment for non-laryngeal and non-hypopharyngeal head and neck cancers and may preserve voice quality.

Image-guided radiotherapy for cardiac sparing in patients with left-sided breast cancer

Patients with left-sided breast cancer are at risk of cardiac toxicity because of cardiac irradiation during radiotherapy with the conventional 3-dimensional conformal radiotherapy technique. In addition, many patients may receive chemotherapy prior to radiation, which may damage the myocardium and may increase the potential for late cardiac complications. New radiotherapy techniques such as intensity-modulated radiotherapy (IMRT) may decrease the risk of cardiac toxicity because of the steep dose gradient limiting the volume of the heart irradiated to a high dose. Image-guided radiotherapy (IGRT) is a new technique of IMRT delivery with daily imaging, which may further reduce excessive cardiac irradiation. Preliminary results of IGRT for cardiac sparing in patients with left-sided breast cancer are promising and need to be investigated in future prospective clinical studies.

Potential Applications of Image-Guided Radiotherapy for Radiation Dose Escalation in Patients with Early Stage High-Risk Prostate Cancer

Patients with early stage high-risk prostate cancer (prostate specific antigen > 20, Gleason score > 7) are at high risk of recurrence following prostate cancer irradiation. Radiation dose escalation to the prostate may improve biochemical-free survival for these patients. However, high rectal and bladder dose with conventional three-dimensional conformal radiotherapy may lead to excessive gastrointestinal and genitourinary toxicity. Image-guided radiotherapy (IGRT), by virtue of combining the steep dose gradient of intensity-modulated radiotherapy and daily pretreatment imaging, may allow for radiation dose escalation and decreased treatment morbidity. Reduced treatment time is feasible with hypo-fractionated IGRT and it may improve patient quality of life.

Feasibility of Tomotherapy-Based Image-Guided Radiotherapy for Locally Advanced Oropharyngeal Cancer

PURPOSE The study aims to assess the feasibility of tomotherapy-based image-guided (IGRT) radiotherapy for locally advanced oropharyngeal cancer. A retrospective review of 33 patients undergoing concurrent chemoradiation for locally advanced oropharyngeal cancers was conducted. Radiotherapy planning, treatment toxicity and loco-regional control were assessed. RESULTS At a median follow-up of 32 months (6-47 months), no patient developed loco-regional recurrence. Two patients (6%) developed distant metastases. Grade 3-4 acute toxicity was respectively 72% and 25% for mucositis and gastrointestinal toxicity. Two patients (6%) had long-term dependence on tube feedings. Dose-volume histogram demonstrated excellent target volume coverage and low radiation dose to the organs at risk for complications. CONCLUSIONS AND CLINICAL RELEVANCE IGRT provides excellent loco-regional control but acute toxicity remains significant and needs to be addressed in future prospective trials. The feasibility of Tomotherapy to decrease radiation dose to the normal tissues merits further investigations.

Feasibility of Tomotherapy-Based Image-Guided Radiotherapy to Reduce Aspiration Risk in Patients with Non-Laryngeal and Non-Pharyngeal Head and Neck Cancer

Purpose The study aims to assess the feasibility of Tomotherapy-based image-guided radiotherapy (IGRT) to reduce the aspiration risk in patients with non-laryngeal and non-hypopharyngeal cancer. A retrospective review of 48 patients undergoing radiation for non-laryngeal and non-hypopharyngeal head and neck cancers was conducted. All patients had a modified barium swallow (MBS) prior to treatment, which was repeated one month following radiotherapy. Mean middle and inferior pharyngeal dose was recorded and correlated with the MBS results to determine aspiration risk. Results Mean pharyngeal dose was 23.2 Gy for the whole group. Two patients (4.2%) developed trace aspiration following radiotherapy which resolved with swallowing therapy. At a median follow-up of 19 months (1–48 months), all patients were able to resume normal oral feeding without aspiration. Conclusion and Clinical Relevance IGRT may reduce the aspiration risk by decreasing the mean pharyngeal dose in the presence of large cervical lymph nodes. Further prospective studies with IGRT should be performed in patients with non-laryngeal and non-hypopharyngeal head and neck cancers to verify this hypothesis.