Dose reduction to normal tissues as compared to the gross tumor by using intensity modulated radiotherapy in thoracic malignancies

BACKGROUND AND PURPOSE: Intensity modulated radiotherapy (IMRT) is a powerful tool, which might go a long way in reducing radiation doses to critical structures and thereby reduce long term morbidities. The purpose of this paper is to evaluate the impact of IMRT in reducing the dose to the critical normal tissues while maintaining the desired dose to the volume of interest for thoracic malignancies. MATERIALS AND METHODS: During the period January 2002 to March 2004, 12 patients of various sites of malignancies in the thoracic region were treated using physical intensity modulator based IMRT. Plans of these patients treated with IMRT were analyzed using dose volume histograms. RESULTS: An average dose reduction of the mean values by 73% to the heart, 69% to the right lung and 74% to the left lung, with respect to the GTV could be achieved with IMRT. The 2 year disease free survival was 59% and 2 year overall survival was 59%. The average number of IMRT fields used was 6. CONCLUSION: IMRT with inverse planning enabled us to achieve desired dose distribution, due to its ability to provide sharp dose gradients at the junction of tumor and the adjacent critical organs

Intensity modulated radiotherapy in abdominal malignancies: Our experience in reducing the dose to normal structures as compared to the gross tumor

Background and Purpose: A better understanding of appropriate sequencing and use of multimodality approach in the management and subsequent improvement in overall survival mandates a vigil on quality of life issues. Intensity modulated radiotherapy (IMRT) is a powerful tool, which might go a long way in reducing radiation doses to critical structures and thereby reduce long term morbidities. The purpose of this paper is to evaluate the impact of IMRT in reducing the dose to the critical normal tissues while maintaining the desired dose to the volume of interest for abdominal malignancies. Materials and Methods: During the period January 2002 to March 2004, 11 patients of various sites of malignancies in the abdominal region were treated using physical intensity modulator based IMRT. Plans of these patients treated with IMRT were analyzed using dose volume histograms. Results: An average dose reduction of the mean values by 50% to the liver, 57% to the right kidney, 56% to the left kidney, 66% to the cord and 27% to the bowel, with respect to the GTV could be achieved with IMRT. The two-year disease free survival was 79% and two-year overall survival was 88%. The average number of IMRT fields used was six. Conclusion: IMRT with inverse planning enabled us to achieve desired dose distribution, due to its ability to provide sharp dose gradients at the junction of tumor and the adjacent critical organs

Reirradiation with IMRT for recurrent head and neck cancer: A single-institutional report on disease control, survival, and toxicity

AimTo study and explores the feasibility and efficacy of re-irradiation (Re-RT) for locally recurrent head and neck cancer (HNC) and second primary (SP) malignancies.BackgroundThe most common form of treatment failure after radiotherapy (RT) for HNC is loco-regional recurrence (LRR), and around 20–50% of patients develop LRR. Re-irradiation (Re-RT) has been the primary standard of care in the last decade for unresectable locally recurrent/SP HNC.Materials and methodsIt was a retrospective analysis in which we reviewed the medical records of 51 consecutive patients who had received Re-RT to the head and neck region at our institute between 2006 and 2015.ResultsForty-eight patients were included for assessment of acute and late toxicities, response evaluation at 3 months post Re-RT, and analyses of locoregional control (LRC) and overall survival (OS). The median LRC was 11.2 months, and at 2 and 5 years the LRC rates were 41% and 21.2%, respectively. A multivariate analysis revealed two factors: initial surgical resection performed prior to Re-RT, and achievement of CR at 3 months after completion of Re-RT to be significantly associated with a better median LRC. The median OS was 28.2 months, and at 1, 2, and 5 years, OS were 71.1%, 55.9% and 18%, respectively. A multivariate analysis revealed initial surgical resection performed prior to Re-RT, and achievement of CR at 3 months post completion of Re-RT being only two factors significantly associated with a better median OS. Acute toxicity reports showed that no patients developed grade 5 toxicity, and 2 patients developed grade 4 acute toxicities.ConclusionRe-RT for the treatment of recurrent/SP head and neck tumors is feasible and effective, with acceptable toxicity. However, appropriate patient selection criteria are highly important in determining survival and treatment outcomes

Utilization and incorporation of tumor volume data in staging and prognostication of head and neck squamous cell carcinoma treated with definitive radiotherapy: A systematic review

Head and neck squamous cell cancers (HNSCC) are a group of heterogeneous tumors, evident by their diverse behavior and natural history. The largest diameter of tumor measured for T classification may not necessarily reflect the true tumor dimension. There is a need to take into account certain other feature(s) of these tumors other than the maximum single dimension which can reflect the true tumor burden more accurately. Tumor volume has been shown to be a useful and accurate tool burden because it is a measurement of tumor burden in all three dimensions. This review article has compiled and reviewed the literature published in past on impact of tumor volumes (TVs) on the prognosis of head and neck cancers. A comprehensive literature search was performed in PubMed for terms “clonogens,” “TV” or “primary TV (PTV)” or “nodal volume” or “total TV (TTV)” or “volumetric analysis of TV in head and neck” or “predicting response in head and neck cancer” “prognostic factors head and neck cancers” and “outcome in head and neck cancer.” We identified 33 studies which have commented on the impact of TV in HNSCC on treatment outcome, 9 of these had analyzed PTV, 11 studies had analyzed total nodal volume, and 14 studies have analyzed TTV. Besides these, we have dealt with laryngeal cancers separately with 9 studies. This review article is also aimed to enhance our knowledge further regarding how best a physician can incorporate TV data in staging and predicting response to radiotherapy

Tumour volumes: Predictors of early treatment response in locally advanced head and neck cancers treated with definitive chemoradiation

AimTo analyse and predict early response 3 months post definitive chemoradiation (CCRT) utilising tumour volume (TV) measurement in locally advanced head and neck cancers (LAHNC).BackgroundLAHNC are 3-dimentional lesions. The largest diameter of these tumours measured for T-classification may not necessarily reflect the true tumour dimensions. TV accurately reflects the tumour burden because it is a measurement of tumour burden in all three dimensions.Materials and methodsIt is a single institutional prospective study including 101 patients with LAHNC treated with definitive CCRT. TV data noted were primary tumour volume (PTV), total nodal volume (TNV) and total tumour volume (TTV). Response evaluation was done at 3 months after the completion of definitive CCRT and patients were categorised either having achieved complete response (CR) or residual disease.ResultsPatients who had not achieved CR were found to have larger TV compared with those who had achieved CR. There were significant inverse correlations between PTV and response (median 16.37[[ce:hsp sp="0.25"/]]cm3 vs. 45.2[[ce:hsp sp="0.25"/]]cm3; p[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]0.001), and between TTV and response (median 36.14[[ce:hsp sp="0.25"/]]cm3 vs. 66.06[[ce:hsp sp="0.25"/]]cm3; p[[ce:hsp sp="0.25"/]

Intensity modulated radiotherapy in abdominal malignancies: Our experience in reducing the dose to normal structures as compared to the gross tumor

Background and Purpose: A better understanding of appropriate sequencing and use of multimodality approach in the management and subsequent improvement in overall survival mandates a vigil on quality of life issues. Intensity modulated radiotherapy (IMRT) is a powerful tool, which might go a long way in reducing radiation doses to critical structures and thereby reduce long term morbidities. The purpose of this paper is to evaluate the impact of IMRT in reducing the dose to the critical normal tissues while maintaining the desired dose to the volume of interest for abdominal malignancies. Materials and Methods: During the period January 2002 to March 2004, 11 patients of various sites of malignancies in the abdominal region were treated using physical intensity modulator based IMRT. Plans of these patients treated with IMRT were analyzed using dose volume histograms. Results: An average dose reduction of the mean values by 50% to the liver, 57% to the right kidney, 56% to the left kidney, 66% to the cord and 27% to the bowel, with respect to the GTV could be achieved with IMRT. The two-year disease free survival was 79% and two-year overall survival was 88%. The average number of IMRT fields used was six. Conclusion: IMRT with inverse planning enabled us to achieve desired dose distribution, due to its ability to provide sharp dose gradients at the junction of tumor and the adjacent critical organs

Dosimetric impact of setup errors in head and neck cancer patients treated by image-guided radiotherapy

To assess and analyze the impact of setup uncertainties on target volume coverage and doses to organs at risk (OAR) in head and neck cancer (HNC) patients treated by image-guided radiotherapy (IGRT). Translational setup errors in 25 HNC patients were observed by kilovoltage cone beam computed tomography (kV CBCT). Two plans were generated. Plan one – the original plan which was the initially optimized and approved plan of the patient. All patients were treated according to their respective approved plans at a defined isocenter. Plan two – the plan sum which was the sum of all plans recalculated at a different isocenter according to setup errors in x, y, and z-direction. Plan sum was created to evaluate doses that would have been received by planning target volume (PTV) and OARs if setup errors were not corrected. These 2 plans were analyzed and compared in terms of target volume coverage and doses to OARs. A total 503 kV CBCT images were acquired for evaluation of setup errors in 25 HNC patients. The systematic (mean) and random errors (standard deviation) combined for 25 patients in x, y, and z directions were 0.15 cm, 0.21 cm, and 0.19 cm and 0.09 cm, 0.12 cm, and 0.09 cm, respectively. The study showed that there was a significant difference in PTV coverage between 2 plans. The doses to various OARs showed a nonsignificant increase in the plan sum. The correction of translational setup errors is essential for IGRT treatment in terms of delivery of planned optimal doses to target volume