Accelerated Hypofractionated Radiation Therapy Using Helical Tomotherapy for the Treatment of Medically Inoperable Pleural Mesothelioma: IRST Preliminary Data

Abstract

Purpose/Objective(s)To assess the feasibility of total pleural radiation therapy in non-operable mesothelioma using an accelerated hypofractionated schedule and helical Tomotherapy, according to the RT IRST Protocol and to evaluate whether the dose distribution to the organs at risk (BED2Gy) exceed the normal tissue tolerance limits.Materials/MethodsBetween January 2008 and December 2011, 24 patients diagnosed with medically inoperable malignant pleural mesothelioma (T2/4N0/3) were treated by helical Tomotherapy. There were 21 cases of pathologically confirmed epithelioid mesothelioma, 1 sarcomatoid mesothelioma, and 2 cases of biphasic mesothelioma. Respiratory functional examinations were performed before and after treatment. Nineteen patients had previously received chemotherapy (cisplatin and pemetrexed). A chest CT simulation scan (3-mm thick slices and free breathing) was performed for all cases. Three different volumes of interest (VOI) were contoured, according to the RT IRST Protocol:1.All the pleurae (involved and non-involved pleura plus diagnostic fistula),2.Total ipsilateral lung, and3.Total pleural volume with a 1-cm isotropic reduction.The dose prescription was 25 Gy/5 daily fractions at the reference isodose (60%-70% isodose) with an increasing dose inhomogeneity of up to 37.5-40 Gy inside the reference isodose. The esophagus, heart, spinal cord, ipsilateral kidney, liver and contralateral lung were always identified as organs at risk (OAR).ResultsAll patients were treated without severe respiratory complications. The dose constraint used in the opposite lung was V5/5Gy and the average dose was lower than 4 Gy. The OAR dose tolerance limits were not exceeded in any patient and were maintained below the values of conventional radiation therapy. No grade 3/4 acute reactions according to the RTOG scale were observed.ConclusionsOur preliminary data suggest that accelerated hypofractionated radiation therapy for inoperable pleural mesothelioma is feasible and safe using helical Tomotherapy. Patient compliance to this type of palliative treatment is satisfactory due to the short duration of treatment. Heavy functional injury was also absent. The IRST protocol is ongoing. Purpose/Objective(s)To assess the feasibility of total pleural radiation therapy in non-operable mesothelioma using an accelerated hypofractionated schedule and helical Tomotherapy, according to the RT IRST Protocol and to evaluate whether the dose distribution to the organs at risk (BED2Gy) exceed the normal tissue tolerance limits. To assess the feasibility of total pleural radiation therapy in non-operable mesothelioma using an accelerated hypofractionated schedule and helical Tomotherapy, according to the RT IRST Protocol and to evaluate whether the dose distribution to the organs at risk (BED2Gy) exceed the normal tissue tolerance limits. Materials/MethodsBetween January 2008 and December 2011, 24 patients diagnosed with medically inoperable malignant pleural mesothelioma (T2/4N0/3) were treated by helical Tomotherapy. There were 21 cases of pathologically confirmed epithelioid mesothelioma, 1 sarcomatoid mesothelioma, and 2 cases of biphasic mesothelioma. Respiratory functional examinations were performed before and after treatment. Nineteen patients had previously received chemotherapy (cisplatin and pemetrexed). A chest CT simulation scan (3-mm thick slices and free breathing) was performed for all cases. Three different volumes of interest (VOI) were contoured, according to the RT IRST Protocol:1.All the pleurae (involved and non-involved pleura plus diagnostic fistula),2.Total ipsilateral lung, and3.Total pleural volume with a 1-cm isotropic reduction.The dose prescription was 25 Gy/5 daily fractions at the reference isodose (60%-70% isodose) with an increasing dose inhomogeneity of up to 37.5-40 Gy inside the reference isodose. The esophagus, heart, spinal cord, ipsilateral kidney, liver and contralateral lung were always identified as organs at risk (OAR). Between January 2008 and December 2011, 24 patients diagnosed with medically inoperable malignant pleural mesothelioma (T2/4N0/3) were treated by helical Tomotherapy. There were 21 cases of pathologically confirmed epithelioid mesothelioma, 1 sarcomatoid mesothelioma, and 2 cases of biphasic mesothelioma. Respiratory functional examinations were performed before and after treatment. Nineteen patients had previously received chemotherapy (cisplatin and pemetrexed). A chest CT simulation scan (3-mm thick slices and free breathing) was performed for all cases. Three different volumes of interest (VOI) were contoured, according to the RT IRST Protocol:1.All the pleurae (involved and non-involved pleura plus diagnostic fistula),2.Total ipsilateral lung, and3.Total pleural volume with a 1-cm isotropic reduction. The dose prescription was 25 Gy/5 daily fractions at the reference isodose (60%-70% isodose) with an increasing dose inhomogeneity of up to 37.5-40 Gy inside the reference isodose. The esophagus, heart, spinal cord, ipsilateral kidney, liver and contralateral lung were always identified as organs at risk (OAR). ResultsAll patients were treated without severe respiratory complications. The dose constraint used in the opposite lung was V5/5Gy and the average dose was lower than 4 Gy. The OAR dose tolerance limits were not exceeded in any patient and were maintained below the values of conventional radiation therapy. No grade 3/4 acute reactions according to the RTOG scale were observed. All patients were treated without severe respiratory complications. The dose constraint used in the opposite lung was V5/5Gy and the average dose was lower than 4 Gy. The OAR dose tolerance limits were not exceeded in any patient and were maintained below the values of conventional radiation therapy. No grade 3/4 acute reactions according to the RTOG scale were observed. ConclusionsOur preliminary data suggest that accelerated hypofractionated radiation therapy for inoperable pleural mesothelioma is feasible and safe using helical Tomotherapy. Patient compliance to this type of palliative treatment is satisfactory due to the short duration of treatment. Heavy functional injury was also absent. The IRST protocol is ongoing. Our preliminary data suggest that accelerated hypofractionated radiation therapy for inoperable pleural mesothelioma is feasible and safe using helical Tomotherapy. Patient compliance to this type of palliative treatment is satisfactory due to the short duration of treatment. Heavy functional injury was also absent. The IRST protocol is ongoing.