ESTRO 38 Abstract book

S435 ESTRO 38

cancer

patients

treated

with

definitive

chemoradiotherapy.

PO-0830 Assessment of setup margins and additional subsite anisotropic margin expansions in cervical IGRT. P. Naga CH 1 , U. Mahantshetty 1 , A. Nachankar 1 , Y. Ghadi 1 , L. Scaria 1 , D. Aravindakshan 1 , S. Sastri 1 , L. Gurram 1 , S. Shrivastava 1 , P. Naga CH 1 1 Tata memorial hospital, Radiation oncology, Mumbai, India Purpose or Objective The movements of utero-cervical complex, variation in organ filling (rectal and bladder), tumor regression and set-up uncertainties during the course of radiation pose a major challenge for the use of conformal radiation techniques in the treatment of cervical cancers. This prospective, observational study aimed to assess of set-up margins and further sub-site anisotropic margin expansions by quantifying set-up errors and organ motion, respectively in cervical cancer image-guided radiation therapy (IGRT). Material and Methods Patients with locally advanced cervical cancer undergoing definitive pelvic radio (chemo) therapy between April 2011 and April 2017 were included. Daily pre-treatment 3D-volumetric kilo-voltage, cone-beam computed tomography (kV-CBCT) of pelvic region was acquired. Initially co-registration of daily CBCT with the planning CT images was done to match pelvic vessels/CTV pelvic nodal region after initial rigid alignment based on bony anatomy. Subsequently, soft-tissue matching was done to record the residual set-up errors to assess organ motion at the levels of mid-cervical canal and uterine fundus, separately (Figure 1). Figure 1 : Representative sagittal and axial images illustrating CBCT matching at nodal-region CTV, mid- cervical and uterine fundus. Mean translational displacements, systematic, and random errors of the study population for matching at three levels were calculated. Set-up margins for clinical target volume (CTV) to planning target volume (PTV) and additional sub-site an-isotropic margin expansions for cervix and uterine region were derived separately using published margin recipes. Results Data acquired from 1389 kV-CBCT scans of 70 patients was considered for analysis. The recorded mean (±SD) displacements, systematic error ( Ʃ ), random error (σ) distribution along the six directions [left (X+) & right- lateral (X-), anterior (Y+) & posterior (Y-) directions and superior (Z+) & inferior (Z-)] in millimeter for pelvic nodal CTV region, mid-cervix, and uterine fundal matching is tabulated in Table 1. The calculated CTV-to-PTV margin and sub-site an-isotropic margin recipe for 95% coverage were 7.0 & 8.9 (bilaterally), 10.3 & 7.2 (antero- posteriorly) and 8.5 & 9.8 (supero-inferiorly), respectively. The obtained an-isotropic margin expansions for mid-cervix is 7.3 & 7.7, 8.5 & 6.7 and 9.5 & 8.5, respectively. Similarly, for uterine region, 7.3 & 7.6, 10.2 & 10.4 and 20.9 & 12.6, respectively (Table 1).

Table 1 : The mean, SD of target-motion along with systematic error ( Ʃ ), random error (σ) distribution and calculated margin (mm) recipe for 95% coverage in all three translational directions. Conclusion Our prospective study suggests set-up margins (CTV to PTV) to account for daily set-up uncertainties and an additional anisotropic margin for the cervical and uterine regions to account for organ motion during cervical cancer radiotherapy. Further research is warranted to evaluate various adaptive strategies for cervical cancer radiotherapy. PO-0831 Effect of pre-treatment hematological indices on survival in cervical cancer U. Mahantshetty 1 , P. Naga CH 1 , L. Gurram 1 , R. Hawaldar 2 , S. Chopra 3 , S. Gupta 4 , J. Ghosh 5 , J. Bajpai 5 , S. Gulia 5 , J. Agarwal 1 1 Tata Memorial Hospital, Radiation Oncology, Mumbai, India ; 2 Tata Memorial Hospital, Clinical Research Secreteriat, Mumbai, India ; 3 ACTREC- Tata Memorial Centre, Radiation Oncology, Navi Mumbai, India ; 4 ACTREC- Tata Memorial Centre, Medical Oncology, Navi Mumbai, India ; 5 Tata Memorial Hospital, Medical Oncology, Mumbai, India Purpose or Objective Recent emerging evidences support that certain systemic indices of immune inflammation can act as independent prognostic factors for various cancers including cervical cancer. In this study, we investigate prognostic implications of pre-treatment hematological factors/indices in locally advanced cervical cancers treated with radical chemoradiation. Material and Methods The electronic medical records of 1051 cervical cancer patients of FIGO stage IB2 – IVA treated with chemoradiation in prospective studies between 2003 and 2017 were reviewed. All clinical parameters such as age, stage, histological type, nodal involvement and hematological parameters (haemoglobin, platelets, absolute neutrophil count, absolute lymphocyte count, absolute monocyte count) were recorded. Neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR) and lymphocyte/monocyte ratio (LMR) and prognostic nutritional index (PNI, defined as 10 x albumin concentration (g/dl)+0.005 x total lymphocyte count (μl)) were calculated. Univariate and multivariate (Cox regression) analyses was performed to evaluate impact of these factors on disease free survival (DFS) and overall survival (OS). Results With a median follow-up of 57 months (range, 3-169 months), the 5 years DFS and OS were 65% and 66.5%, respectively. Table 1 shows in detail the outcome of univariate and multivariate analyses. On multivariate analysis, FIGO stage (HR, 1.57; p=0.000) and LMR (HR: 0.92; p=0.007) significantly affected DFS while FIGO stage (HR, 1.79; p=0.000), LMR (HR, 0.92; p=0.008), PNI (HR, 0.97; p=0.024) and haemoglobin (HR, 0.93; p=0.039) significantly affected OAS. Apart from FIGO Stage, LMR had a significant impact on both DFS and OAS.