Retrospective Dosimetric analysis of Bone marrow sparing vs non bone marrow sparing Image Guided Volumetric Modulated Arc Therapy in intact Carcinoma Cervix patients

Abstract

Aim: Aim of this study was to compare dosimetric parameters of bone marrow (BM) and non bone marrow sparing with state of the art technique image guided volumetric modulated arc therapy in the treatment of Carcinoma Cervix. Methods and Materials: The retrospective Dosimetric study was conducted on 10 consecutive patients of biopsy-proven invasive cervical cancer attending the outpatient department of Geetanjali cancer centre. For treatment planning, patients were scanned on a GE Optima-520, 16 slice fan-beam CT (FBCT) scanner with 2.5 mm slice thickness in the supine position on a customized vacuum cushion with simulation tattoos and alignment lasers. All the simulation scans were taken after following a bladder and bowel preparation protocol, aimed at an empty rectum and full bladder, starting prior to the initial planning scan and continuing throughout the treatment. The prescribed dose to PTV was 50Gy in 25 fractions (2Gy/fraction) and from second week of radiotherapy 50mg/m 2 /week cisplatin chemotherapy was administered for five weeks. Two sets of plans were generated for all the 10 patients using Volumetric Arc Radiotherapy (VMAT) in Monaco v 5.11.02(Elekta, Crawley, UK) treatment planning system. Keeping all constraints in mind planning optimization was performed with no compromise in coverage of PTV. Results: In the present study V5 , V10 , V20 , V30 were all significantly lower in BMS-IG/VMAT plan. Maximum significance was noted at V20. Value of V40 is lower in BM-IG/VMAT plan, but statistically not significant. Conclusion: Treatment of carcinoma cervix is restricted as a result of toxicity of the surrounding normal structures and HT. HT could be significantly reduced by bone marrow sparing, which could be aided by IGRT/VMAT. This modality could allow completion of treatment with prescribed dose and concurrent chemotherapy in allotted stipulated time. More prospective randomized control trials are needed, to prove its efficacy.

Feasibility of bone marrow sparing volumetric modulated arc therapy to spare active bone marrow in cervical and vaginal cancer patients: a retrospective dosimetric analysis

“…This is inconsistent with literature that has reported bone marrow doses were reduced at all levels, shown in 4. 13,14,16,17 Despite the lack of significance of the V30-40Gy in our study in comparison with the original VMAT group, ABM objective compliance was improved from 50% to 100% for the V30Gy, and 50% to 83.3% for the V40Gy. Furthermore, our actual dose reduction at the V30Gy is comparable to that reported by Liang et al, which was significant at all dose levels.…”

“…This overestimates the bone marrow contours, leading to over-optimisation of these contours and constraining the optimisation process. 13,17 Prospective trials in this area are few, with Mell et al conducting the only trial investigating FDG-PET-defined ABM specifically in cervical cancer (n = 83) reporting reductions in the rate of HT. 14 Despite the differences in ABM delineation, all studies demonstrated, dosimetrically, that dose to the ABM can be reduced without compromise of target coverage or organs at risk (OAR) dose.…”

“… 7 , 8 , 9 , 10 , 11 , 12 Bone marrow sparing (BMS) techniques aim to reduce HT associated with CRT treatment, primarily focussing on pelvic sites. 8 , 13 , 14 , 15 , 16 , 17 Proximity of the bone marrow to the planning target volume (PTV) can be technically challenging; however, with the use of techniques such as volumetric modulated arc therapy (VMAT), BMS techniques may be plausible in achieving bone marrow reductions.…”

“…Further uncertainty is enhanced by the inconsistency of bone marrow delineation across studies. 8 , 13 , 14 , 15 , 16 , 17 Fluorodeoxyglucose positron emission tomography (FDG‐PET) has been demonstrated to be superior to computerised tomography (CT), which cannot distinguish between active and inactive areas, in defining haematopoietically active bone marrow (ABM) for HT predictions. 9 , 16 , 18 , 19 Its use in other retrospective studies is limited, with BMS‐VMAT (excluding intensity modulated radiotherapy (IMRT)) studies delineating bone marrow based on CT only.…”

“…This overestimates the bone marrow contours, leading to over‐optimisation of these contours and constraining the optimisation process. 13 , 17 Prospective trials in this area are few, with Mell et al. conducting the only trial investigating FDG‐PET‐defined ABM specifically in cervical cancer ( n = 83) reporting reductions in the rate of HT.…”