ESTRO 37 Abstract book

ESTRO 37

S425

Material and Methods Medical records of pts treated in our institution between 09/2009 and 02/ 2012 by CRT (45 Gy in 25 fractions +/− nodal boosts) and concurrent weekly platine-based chemotherapy were reviewed. Baseline and weekly hematological parameters during CRT were collected, including leukocyte, hemoglobin, absolute neutrophil, platelet, and lymphocyte count. BM was retrospectively delineated in each pt individually: (1) lumbosacral region (L5 and sacrum), (2) iliac crests, and (3) lower pelvis (pubis and femoral heads). Relative dose volume histograms (DVHs) were calculated. BM volumes receiving 5, 10, 15, 20, 30, 40Gy (V5, V10, V15, V20, V30, V40 respectively) and mean dose were calculated for each volume. HT was graded according to Common Terminology Criteria for Adverse Events (CTCAE), version 4.0. Receiver operating characteristic curve analysis was performed for determining the cut-off value for dosimetric parameters. Logistic regression was used to analyze association between HT and DVHs parameters.

and CTV-N D50≥101.5%. Acute side effects were scored using CTCAEv4.0. Results In total, thirty-three nodes (range:1-4/pts) were boosted. Planning aims for CTV-N D98/D50 and PTV-N D98 were achieved in 91% and 88% of the nodes, respectively. Hard constraints for organs at risks were fulfilled in ≥ 90% of the cases (Table). After a mean follow up of 5 months (1.5-17) all boosted nodes are in complete remission. No nodal failure occurred in the elective RT regions. There was no ≥Gr. 3 gastrointestinal and genitourinary acute side effect; the dominant Grade 2 toxicity was diarrhea (7 pts). 9/12 patients received ≥ 4 cycles of cisplatin and Gr.3 anemia/neutropenia occurred exclusively in patients receiving PAO irradiation (3 pts) as well. One patient developed an isolated local recurrence six months after treatment, while one patient failed only systemically in the lung.

Results 118 patients were included, 75% treated with 3D radiation therapy (3D-RT), and 25% with intensity modulated radiation therapy (IMRT). 100 (85%) pts received at least 5 cycles of concurrent chemotherapy. All blood cell lines included, grade (Gr) 0-1, 2, 3 and 4 HT were reported in 8 (7%), 25 (21%), 76 (64%), and 9 pts (8%) respectively. Neither radiation technique (3D-RT vs IMRT), chemotherapy regimen (Cisplatin vs Carboplatin), or para-aortic irradiation were associated with HT. On univariate analysis, Gr3+ neutropenia correlated with lower pelvis V15 > 68% (RR 1.2; p = 0.007), lower pelvis V30 > 24% (RR 1.17; p = 0.03). Gr4 HT correlated with lower pelvis V20 > 46% (OR 5.7; p = 0.02; 95%CI: 1.1-28.7) and iliac crests V10 > 92% (OR 8.2; p = 0.02), V20 > 63% (OR 7.0; p = 0.04,), V30 > 46% (OR 6.7; p = 0.04). In multivariate analysis including other significant parameters in univariate analysis (body mass index < 25, p=0.01; number of chemotherapy cycles > 5, p = 0.001), grade 4 HT was associated with lower pelvis V20 > 46% (OR 7.5; p = 0.04; 95% CI: 1.3-63.4). Conclusion In our cohort, there was a correlation between BM volume irradiated and HT. Low doses of radiation therapy were more closely associated with HT than high doses. This has clinical implications since the volume of iliac crests receiving doses < 30Gy were higher in the IMRT group (p < 0.03). From this work, the following dose constraint could be suggested as follows: lower pelvis: V20 < 46%.

Conclusion Planning aims for CovP based nodal SIB boost were achievable and the technique seems to be feasible in terms of acute toxicity and very early nodal control. Further follow-up and larger numbers of patients are needed to confirm clinical benefit. PO-0815 Correlation between pelvic bone marrow radiation dose and hematologic toxicity in cervical cancer T. Kumar 1,2 , A. Schernberg 3 , F. Busato 1 , M. Laurans 1 , E. Manea 1 , I. Dumas 1 , P. Maroun 1 , C. Berthold 3 , I. Lazarescu 1 , E. Deutsch 3 , C. Haie-Meder 1 , C. Chargari 1 1 Gustave Roussy, Brachytherapy unit - Radiotherapy department, 114 Rue Edouard Vaillant- 94800 Villejuif, France 2 University hospital of Grenoble, Radiotherapy department, Avenue Maquis du Grésivaudan- 38700 La Tronche, France 3 Gustave Roussy, Radiotherapy department, 114 Rue Edouard Vaillant- 94800 Villejuif, France Purpose or Objective Acute hematologic toxicity (HT) may limit the optimal treatment in cervical cancer patients (pts). We studied associations between the delivered radiation dose to the pelvic bone marrow (BM) and acute HT in a large cohort of cervical cancer pts receiving definitive chemoradiation (CRT) plus image-guided adaptive brachytherapy.