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WE‐AB‐207B‐04: A Preliminary Investigation of Indicators for Treatment Outcomes of CT Guided Cervical Cancer Brachytherapy
Author(s) -
Meerschaert R,
Paul A,
Chen W,
Miller S,
Zhuang L
Publication year - 2016
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4957785
Subject(s) - medicine , brachytherapy , cervical cancer , cutoff , nuclear medicine , radiation therapy , stage (stratigraphy) , proportional hazards model , radiation treatment planning , biopsy , radiology , external beam radiotherapy , cancer , surgery , paleontology , physics , quantum mechanics , biology
Purpose: To identify indicators for recurrence in cervical cancer patients treated with high‐dose‐rate brachytherapy (HDR‐BT). Methods: A total of 37 biopsy proven uterine cervical cancer patients of stage IB‐IVA treated between 2011 and 2015 were included in this study. All patients were treated with 37.8–52.2Gy of external beam radiotherapy (EBRT) plus 5 × 5.0–6.5Gy of HDR‐BT. Patient age, standard deviation of high‐risk clinical tumor volume (HR‐CTVSD) collected throughout HDR‐BT, and D90 (EQD2, α/β=10Gy) of the HR‐CTV were investigated as potential indicators for local/distant recurrence using ROC analysis. The optimal cutoff value was identified through the Youden index and was subsequently used to obtain a group assignment for all patients. Another two comparing groups were defined per evidence of post‐EBRT tumor shrinkage based on the pre‐HDR MR scan. Kaplan‐Meier curves were generated for recurrence‐free proportions for comparing groups where time was measured from the final HDR treatment date to the date of the final follow‐up exam and compared through Cox regression. Results: Patients had a median follow‐up of 12 months, where 16% had local pelvic recurrence and 16% had distant recurrence. HR‐CTVSD was identified as a statistically significant indicator for recurrence (AUC=0.802, p=0.007) compared to D90 (AUC=0.655, p=0.167) and patient age (AUC=0.683, p=0.103). HR‐CTVSD of 6.26cc was chosen as the optimal cutoff value, which was used as the basis for patient group assignment. Patients with HR‐CTVSD>6.26cc had a hazard ratio of 3.92 (95% CI‐1.37, 11.24; p=0.011) for recurrence compared to HRCTVSD≤ 6.26cc. Patients without evidence of post‐EBRT tumor shrinkage compared to those with had a hazard ratio of 4.28 (95% CI‐1.14, 16.15; p=0.032) for recurrence. Conclusion: HR‐CTVSD was identified as an indicator for recurrence and an optimal value of 6.26cc was established in our study. In addition, patients without evidence of post‐EBRT tumor shrinkage demonstrated an increased recurrence rate.