ESTRO 2020 Abstract book

S342 ESTRO 2020

External beam radiotherapy (EBRT), concurrent chemotherapy and brachytherapy represent standard treatments for locally advanced cervical cancer. It is well kwon as T2-weighted MRI is the gold standard for tumor volume delineation in this setting. Functional Diffusion- Weighted MRI (DWI) images, in combination with T2-MRI, as for other neoplasms, could improve lesion detection. Our study tries to assess the difference in GTV delineation based on T2 weighted and Apparent Diffusion Coefficient maps (ADC-MRI), in order to evaluate volumes and inter- observer agreement between two different specialists, a radiologist and a radiation oncologist, with the aim to improve volumes delineation in cervical cancer patients. Material and Methods Thirty-seven cervical cancer patients (6 adenocarcinoma, 31 epidermoid carcinoma) were evaluated. All patients performed a diagnostic 1.5T MRI, with both axial T2 weighted images and ADC maps, calculated with the use of minimum 2 different b values. Two observers, one radiologist and one radiation oncologist, blinded and independently from each other, delineated GTV on T2 (T2 GTV ) and ADC (ADC GTV ) sequences. GTV volume (cm 3 ) was measured for T2 and ADC for each observer, and evaluated using the t-test. DICE index, Bland-Altman analysis (mean difference, 95% limits of agreement), coefficient of repeatability (CR) and intraclass correlation coefficient (ICC) were used to assess inter-observer agreement. Results Median patients age was 55 years (range: 28-94 years). According to FIGO classification, 2 (5.4%) patients were staged 1B1, 6 (16.2%) patients 2A1, 17 (46%) 2B, 2 (5.4%) 3B and 10 (27%) patients staged 4A. Mean T2 GTV and ADC GTV volumes were 43.84±71.47 cm 3 and 37.28±68.92 cm 3 for radiologist, and 43.4±70.44 cm 3 and 36.65±69.21 cm 3 for radiation oncology, respectively (Table 1). T2 showed significant larger volumes compared to ADC (p<0.001 and p<0.001 for both observers). Mean DICE index, ICC and CR are 0.86, 0.998 and 7.984 for T2 GTV , and 0.84, 0.999 and 5.496 for ADC GTV , respectively (Table 1). Concordance plots for T2 and ADC between observers are shown in Figure 1, respectively. The Bland-Altman plots show some outliers out of the limits of agreements (Figure 1), but globally the methods for the two observers are in accordance, conforming to the CR coefficients reported in Table 1.

Conclusion In cervix cancer, positive nodes (pelvic and PAO) at diagnosis, tumour width, and local recurrence after treatment increase the risk of NF and NF PAO , while a higher Hb-nadir decreases this probability. Additionally, we found elective PAO-radiotherapy decreased the risk of NF PAO and in particular in patients with positive pelvic nodes at diagnosis. More detailed investigations regarding nodal management and nodal control after treatment are part of the on-going EMBRACE II study. OC-0567 T2 and Apparent Diffusion Coefficient MRI for Cervical cancer delineation: agreement between volumes C. Rosa 1 , L. Gasparini 1 , F.C. Di Guglielmo 1 , A. Delli Pizzi 2 , B. Seccia 2 , R. Cianci 2 , R. Basilico 2 , A. Augurio 1 , L.A. Ursini 1 , A. Porreca 3 , M. Di Nicola 4 , L. Caravatta 1 , D. Genovesi 1 1 Ospedale Clinicizzato S.S. Annunziata, Radiotherapy Oncology- Chieti, Chieti, Italy ; 2 Ospedale Clinicizzato S.S. Annunziata, Department of Radiology, Chieti, Italy ; 3 G. D’Annunzio University, Department of Economy, Chieti, Italy ; 4 G. D’Annunzio University, Laboratory of Biostatistics- Department of Medical- Oral and Biotechnological Sciences, Chieti, Italy

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