Introduction of Image­Guided Pencil Beam for Skull Base Tumors in India: A Report of Two Cases and a Brief Review of the Literature.

Chordoma and chondrosarcoma are locally aggressive tumors occurring in one-third cases at the base of the skull. These tumors often recur locally with significant morbidity and mortality. The mainstay of treatment is maximal safe tumor debulking. However, in spite of gross total resection, these tumors are likely to recur. Hence, adjuvant radiation is provided to reduce the risk of local recurrence and to improve outcomes. These tumors are considered relatively radioresistant; hence, high doses of radiation are generally required during treatment. However, the presence of several important structures around the lesion poses a major challenge with respect to covering the target with the prescribed high dose. In this regard, protons, for their physical and dosimetric advantages, have become the accepted modality of treatment in these tumors. With the evolution of proton beam therapy (PBT) over the years, especially pencil beam scanning techniques; which result in an extremely high conformal intensity-modulated proton beam therapy (IMPT), robust and Monte Carlo optimization, computational algorithms, and biological modelling are the significant advances which have further enhanced the value of this technology and have improved outcomes. Herein, we would like to report our experience of two cases of skull base tumors treated with intensity-modulated proton therapy at our center along with a review of the literature.

Protocol for a phase III randomised trial of image-guided intensity modulated radiotherapy (IG-IMRT) and conventional radiotherapy for late small bowel toxicity reduction after postoperative adjuvant radiation in Ca cervix.

INTRODUCTION: External beam radiation followed by vaginal brachytherapy (±chemotherapy) leads to reduction in the risk of local recurrence and improves progression-free survival in patients with adverse risk factors following Wertheim's hysterectomy albeit at the risk of late bowel toxicity. Intensity Modulated Radiotherapy (IMRT) results in reduction in bowel doses and has potential to reduce late morbidity, however, needs to be confirmed prospectively in a randomised trial. The present randomised trial tests reduction if any in late small bowel toxicity with the use of IMRT in postoperative setting. METHODS AND ANALYSIS: Patients more than 18 years of age who need adjuvant (chemo) radiation will be eligible. Patients with residual pelvic or para-aortic nodal disease, history of multiple abdominal surgeries or any other medical bowel condition will be excluded. The trial will randomise patients into standard radiation or IMRT. The primary aim is to compare differences in late grades II-IV bowel toxicity between the two arms. The secondary aims of the study focus on evaluating correlation of dose-volume parameters and late toxicity and quality of life. The trial is planned as a multicentre randomised study. The trial is designed to detect a 13% difference in late grades II-IV bowel toxicity with an α of 0.05 and ß of 0.80. A total of 240 patients will be required to demonstrate the aforesaid difference. ETHICS AND DISSEMINATION: The trial is approved by institutional ethics review board and will be routinely monitored as per standard guidelines. The study results will be disseminated via peer reviewed scientific journals, conference presentations and submission to regulatory authorities. REGISTRATION: The trial is registered with clinicaltrials.gov (NCT 01279135).