Genitourinary Cancer

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TU_13_3449 - The Relationships between DVH Parameters and Oncologic Outcomes in Locally Advanced Cervical Cancer Patients Treated with Definitive Radiation Therapy: A Mono-Institutional Retrospective Study

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

The Relationships between DVH Parameters and Oncologic Outcomes in Locally Advanced Cervical Cancer Patients Treated with Definitive Radiation Therapy: A Mono-Institutional Retrospective Study
G. Cheng1, M. He2, Y. Lu3, and D. Han4; 1China-Japan Union Hospital of Jilin University, Changchun, China, 2Department of Radiation Oncology, China-Japan Union Hospital of Jilin University, Changchun, China, 3Department of Radiation Oncology, China-Japan Union Hospital of Jilin University,, Changchun, China, 4China-Japan Union Hospital of Jilin University, Changchun, China, Changchun, China

Purpose/Objective(s): The purpose of this study was to quantify the effect of dose-volume histogram (DVH) parameters on survival and local control (LC) in locally advanced cervical cancer patients treated with radical radiotherapy.

Materials/Methods: We retrospectively analyzed 110 patients of locally advanced cervical cancer treated with external beam radiotherapy (EBRT) ± chemotherapy combined with interstitial brachytherapy from 2010 to 2017. Following the GEC-ESTRO/ICRU recommendations, DVH parameters including D90 of intermediate and high risk clinical target volume (CTVIR D90 and CTVHR D90), D2cm3 of organs at risk (OARs), DICRU of rectum and bladder were reported. All doses were normalized to total biologically equivalent dose in 2 Gy per fraction (EQD2) using a linear-quadratic model with α/β= 10 Gy for tumor and α/β= 3 Gy for OARs. Adverse effect referred to RTOG criteria. Overall survival (OS), cancer specific survival (CSS) and LC were analyzed via Kaplan Meier method. Dose-volume effect relationships were assessed using multivariate Cox Proportional Hazards regression and Probit model.

Results: Median age and follow-up was 53.98 years and 72.33 months respectively. FIGO stage distribution was I (5.45%), II (71.82%), III (20.0%) and IV (2.73%). The histopathology included squamous cell carcinoma (94.54%), adenocarcinoma (3.64%) and others (1.82%). 64.55% of patients received concurrent chemotherapy. EBRT dose was delivered by 3D conformal EBRT (20%) or intensity modulated radiotherapy (80%). Mean CTVIR D90 was 68.47 ± 3.79, CTVHR D90 was 91.28 ± 8.63; mean D2cm3 was: rectum 64.72 ± 7.47, bladder 77.20 ± 7.04, colon 63.49 ± 8.46, bowel 61.52 ± 7.04. Mean DICRU for rectum was 67.22 ± 7.87, for bladder was 76.72 ± 11.48. Rates of late gastrointestinal and genitourinary were 22.7% and 6.4%. There were no RTOG grade 4 toxicities. The 3/5-year OS, CSS and LC were 79.09%/76.36%, 81.82%/80.00% and 90.00%/90.00% respectively. On the premise of adjusting variables, Forward selection regression model showed that CTVHR D90, which had significant dose effect relationships with OS (0.94 [0.90, 0.98], p= 0.004), CSS (0.95 [0.90, 0.99], p= 0.036) and LC (0.90 [0.83, 0.97], p= 0.01), was the only independent prognostic variable for survival and LC. The Probit model presented that 87 Gy (P25), 91 Gy (P50) and 97 Gy (P75) of CTVHR D90 resulted in 68.19%, 71.37% and 76.14 of 5-year OS, 73.23%, 74.93% and 77.48% of 5-year CSS, and 83.54%, 85.48% and 88.38% of 5-year LC. It demonstrated dose escalation of CTVHR D90 from 87 Gy to 97 Gy contributed to increased 5-year OS, CSS and LC by 7.95%, 4.25% and 2.83%, respectively.

Conclusion: CTVHR D90 may be used to predict incidence of OS, CSS and LC in locally advanced cervical cancer patients treated with radical radiotherapy. And CTVHR D90 ≥ 97 Gy was associated with promising survival and LC.

Author Disclosure: G. Cheng: None. M. He: None. D. Han: None.

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