ESTRO 36 Abstract Book

S168 ESTRO 36 2017 _______________________________________________________________________________________________

Scienza, Department of Medical Sciences, Torino, Italy 6 A.O.U. Citta' della Salute e della Scienza- Turin, Department of Oncology- Medical Oncology, Torino, Italy 7 University of Turin A.O.U. Citta' della Salute e della Scienza, Department of Medical Imaging, Torino, Italy 8 A.O.U. Citta' della Salute e della Scienza- Turin, Department of Oncology- Radiation Oncology, Torino, Italy Purpose or Objective To test the proof of principle that irradiated volume of pelvic active bone marrow ( ACT BM), as detected by 18 FDG- PET, may be a predictor of decreased blood cell nadirs in anal cancer patients undergoing concurrent chemo- radiation and to identify subregions within the pelvis potentially more involved in the occurrence of acute Forty four patients submitted to IMRT and concurrent chemotherapy were analyzed. Several bony structures were defined: pelvic and lumbar-sacral (LSBM), lower pelvis (LPBM) and iliac (IBM) bone marrow. ACT BM was characterized employing 18 FDG-PET and defined as all subregions within pelvic bone marrow having Standard Uptake Values (SUVs) higher than SUV mean . All other regions were defined as inactive BM ( INACT BM) (Figure 1). On dose- volume histograms, dosimetric parameters were taken. Endpoints included white blood-cell-count (WBC), absolute-neutrophil-count (ANC), hemoglobin (Hb) and platelet (Plt) nadirs. Acute toxicity was scored according to RTOG scoring scale. Generalized linear and logistic regression models were used to find correlations between dosimetric variables and blood cell toxicity. hematologic toxicity. Material and Methods Results act BM mean dose had a statistically significant correlation with WBC (β=-1.338; 95%CI: -2.455/-0.221; p=0.020), ANC (β=-1.651; 95%CI: -3.284/-0.183; p=0.048) and Plt (β=- 0.031; 95%CI: -0.057/-0.004; p=0.024) nadirs. On the contrary, no correlation was found between inact BM mean dose and any blood cell nadir (Table 1). act BM V 10 had a significant correlation with WBC (β=-0.062; 95%CI: - 0.104/-0.021; p=0.004) and ANC (β=-0.038; 95%CI: - 0.067/-0.007; p=0.015) nadirs. act BM V 20 was significantly correlated to WBC (β=-0.044; 95%CI: -0.080/-0.008; p=0.017), ANC (β=-0.027; 95%CI: -0.052/-0.001; p=0.039) and Plt (β=-1.570; 95%CI: -3.140/-0.002; p=0.050) nadirs. act BM V 30 had a significant correlation with WBC (β=-0.033; 95%CI: -0.064/-0.002; p=0.036) and Plt (β=- 1.720; 95%CI: -2.990/-0.450; p=0.010) nadirs. act BM V 40 was significantly correlated to WBC (β=-1.490; 95%CI: -2.900/- 0.072; p=0.040) nadir. With respect to subregions within the pelvis, WBC nadir was significantly correlated to act LSBM mean dose (β=-1.852; 95%CI: -3.205/-0.500; p=0.009), V 10 (β=-2.153; 95%CI: -4.263/-0.721; p=0.002), V 20 (β=-2.081; 95%CI: -4.880/-0.112; p=0.003), V 30 (β=- 1.971; 95%CI: -4.748/-0.090; p=0.023) and to act IBM V 10 (β=-0.073; 95%CI: -0.106/-0.023; p=0.016). ANC nadir found to be significantly associated to act LSBM V 10 (β=- 1.878; 95%CI: -4.799/-0.643; p=0.025), V 20 (β=-1.765; 95%CI: -4.050/-0.613; p=0.030). No significant correlation were found between dosimetric parameters and > G3 hematologic toxicity, even if borderline significance was found for act LSBM mean dose and WBC nadir.

This retrospective cohort study includes consecutive OC patients staged with PET/CT between October 2010 and December 2014. PET-defined tumour variables and texture metrics were obtained using ATLAAS, a machine learning algorithm for optimised automatic segmentation. A Cox regression model including age, radiological stage, treatment and 12 novel texture variables was developed and a prognostic score stratifying patients into quartiles was calculated. Primary outcome was OS and a p-value <0.1 was considered statistically significant. Results Three hundred and forty-three consecutive patients [median age=67 (range=24-83), adenocarcinoma=258] were included. Median survival was 17 months (95% CI 14.685–19.315). Multivariate analysis demonstrated 7 variables that were significantly and independently associated with OS; age [HR=1.024 (95% CI 1.010-1.038), p<0.001], radiological stage [HR=1.492 (1.221-1.823), p<0.001], treatment [HR=2.855 (2.038–3.998), p<0.001], standard deviation [HR=0.898 (0.815–0.989), p=0.029], log(coarseness) [HR=1.774 (0.918–3.43), p=0.088], dissimilarity [HR=1.136 (1.007–1.281), p=0.038] and zone percentage [HR=0.938 (0.897–0.980), p=0.005]. A prognostic score derived from the model equation showed significant differences in OS between quartiles (X 2 =90.13, df=3, p<0.001).

Conclusion This study demonstrates the additional benefit of PET texture analysis in OC staging, over and above the current TNM system. Our prognostic model requires further validation, but highlights the potential of texture analysis to predict survival in OC. PV-0324 FDG-PET based pelvic bone marrow dose predicts for blood cell nadirs in CT-RT for anal cancer P. Franco 1 , F. Arcadipane 1 , R. Ragona 1 , A. Lesca 2 , E. Gallio 3 , M. Mistrangelo 4 , P. Cassoni 5 , M. Baccega 2 , P. Racca 6 , R. Faletti 7 , N. Rondi 8 , M. Morino 4 , U. Ricardi 1 1 University of Turin A.O.U. Citta' della Salute e della Scienza, Department of Oncology- Radiation Oncology, Torino, Italy 2 A.O.U. Citta' della Salute e della Scienza- Turin, Department of Surgical Sciences - Nuclear Medicine, Torino, Italy 3 A.O.U. Citta' della Salute e della Scienza- Turin, Department of Medical Imaging - Medical Physics, Torino, Italy 4 University of Turin A.O.U. Citta' della Salute e della Scienza, Department of Surgical Sciences, Torino, Italy 5 University of Turin A.O.U. Citta' della Salute e della