Gynecological Cancer

PD 15 - GYN 2 - Poster Discussion

1130 - Tumor Shrinkage during Chemoradiation in Locally Advanced Cervical Cancer Patients: Prognostic Significance, and Impact for Image-Guided Adaptive Brachytherapy.

Wednesday, October 24
11:24 AM - 11:30 AM
Location: Room 217 A/B

Tumor Shrinkage during Chemoradiation in Locally Advanced Cervical Cancer Patients: Prognostic Significance, and Impact for Image-Guided Adaptive Brachytherapy.
A. Schernberg1, S. Bockel2, I. Fumagalli1, P. Annede1, A. Escande3, F. Mignot4, M. Kissel1, P. Morice1, E. Deutsch5, C. Haie-Meder6, and C. Chargari1; 1Gustave Roussy, Villejuif, France, 2Institut Gustave Roussy, Villejuif 94805, France, 3Universitary Radiation Oncology Department, Oscar Lambret Comprehensive Cancer Center, Lille, France, 4Institut Curie, Paris, France, 5Gustave Roussy, Université Paris-Saclay, Villejuif, France, 6Radiation Oncology department, Gustave Roussy Cancer Campus, Villejuif, France, Villejuif, France

Purpose/Objective(s): Tumor shrinkage during chemoradiation (CRT) logically reflects tumor radiosensitivity but it has never been examined as a potential biomarker to guide dose (de)escalation indications. This study aimed to evaluate the prognostic value of gross tumor volume (GTV) shrinkage and its dosimetric implication in a large cohort of cervical cancer patients receiving definitive CRT plus image-guided adaptive brachytherapy (IGABT).

Materials/Methods: Clinical records of consecutive patients treated in our Institution between February 2004 and November 2015 by concurrent CRT (45Gy in 25 fractions +/- lymph node boosts) followed by a magnetic resonance imaging (MRI)-guided adaptive pulse-dose rate brachytherapy were included. The prognostic value of GTV and its evolution after CRT were examined first on initial staging MRI and then at time of brachytherapy. Measurements of tumor volume were performed on MRI scans at time of diagnosis and at brachytherapy (T2-weighted sequence). All measures and measurement cutoff were selected using time-dependent Area Under the Curve for 3-year progression-free survival (PFS).

Results: With median follow-up of 4.2 years, relapses were reported in 86 patients (33%). GTV evolution between diagnosis and the time of brachytherapy was assessed in 247 patients. After CRT, complete response was observed in 75 patients (28%). Optimal cutoffs were GTV=55cc at diagnosis, GTV=7.5cc at brachytherapy, and GTV reduction ≥90%. All patients with volume above or reduction below these cutoffs had significant reduced overall survival (OS), PFS, local control (LC) and distant metastasis control (DMC) (p<0.001). Patients with anemia or neutrophilia at diagnosis had a lower tumor volume response rate (p<0.001). Neither CRT duration nor time interval between radiation therapy and brachytherapy were correlated with GTV volume reduction or GTV volume at brachytherapy. In multivariate analysis, incorporating the FIGO stage, N+ stage, anemia, and dosimetric parameters for IGABT, GTV optimal volume reduction after CRT was independently associated with improved OS, PFS, LC, and DMC (p<0.001). Regarding OS, PFS and LC, patients with optimal GTV reduction had no benefit from dose escalation D90 CTVHR ≥80Gy (p>0.3) while patients without optimal GTV reduction had (p<0.05). GTV reduction allowed to determine which patients benefited from CTVHR coverage above 80Gy, while CTVHR volume did not. A probit model for local control probability according to the percentage of tumor shrinkage was developed.

Conclusion: These results provide a rationale for dose de-escalation studies in brachytherapy for patients displaying optimal GTV volumetric reduction after CRT and reinforce the need for dose escalation in poor responding patients.

Author Disclosure: A. Schernberg: None. S. Bockel: None. I. Fumagalli: None. A. Escande: None. C. Chargari: None.

Send Email for Antoine Schernberg


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