Vaginal tolerance of CT based image-guided high-dose rate interstitial brachytherapy for gynecological malignanciesReport as inadecuate




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Radiation Oncology

, 9:31

Clinical Radiation Oncology

Abstract

BackgroundPurpose of this study was to identify predictors of vaginal ulcer after CT based three-dimensional image-guided high-dose-rate interstitial brachytherapy HDR-ISBT for gynecologic malignancies.

MethodsRecords were reviewed for 44 female 14 with primary disease and 30 with recurrence with gynecological malignancies treated with HDR-ISBT with or without external beam radiation therapy. The HDR-ISBT applicator insertion was performed with image guidance by trans-rectal ultrasound and CT.

ResultsThe median clinical target volume was 35.5 ml 2.4-142.1 ml and the median delivered dose in equivalent dose in 2 Gy fractions EQD2 for target volume D90 was 67.7 Gy 48.8-94.2 Gy, doses of external-beam radiation therapy and brachytherapy were combined. For re-irradiation patients, median EQD2 of D2cc for rectum and bladder, D0.5cc, D1cc, D2cc, D4cc, D6cc and D8cc for vaginal wall was 91.1 Gy, 100.9 Gy, 260.3 Gy, 212.3 Gy, 170.1 Gy, 117.1 Gy, 105.2 Gy, and 94.7 Gy, respectively. For those without prior radiation therapy, median EQD2 of D2cc for rectum and bladder, D0.5cc, D1cc, D2cc, D4cc, D6cc and D8cc for vaginal wall was 56.3 Gy, 54.3 Gy, 147.4 Gy, 126.2 Gy, 108.0 Gy, 103.5 Gy, 94.7 Gy, and 80.7 Gy, respectively. Among five patients with vaginal ulcer, three had prior pelvic radiation therapy in their initial treatment and three consequently suffered from fistula formation. On univariate analysis, re-irradiation and vaginal wall D2cc in EQD2 was the clinical predictors of vaginal ulcer p = 0.035 and p = 0.025, respectively. The ROC analysis revealed that vaginal wall D2cc is the best predictor of vaginal ulcer. The 2-year incidence rates of vaginal ulcer in the patients with vaginal wall D2cc in EQD2 equal to or less than 145 Gy and over 145 Gy were 3.7% and 23.5%, respectively, with a statistically significant difference p = 0.026.

ConclusionsRe-irradiation and vaginal D2cc is a significant predictor of vaginal ulcer after HDR-ISBT for gynecologic malignancies. Three-dimensional image-guided treatment planning should be performed to ensure adequate target coverage while minimizing vaginal D2cc in order to avoid vagina ulcer.

KeywordsGynecologic brachytherapy High-dose-rate brachytherapy Interstitial brachytherapy Vaginal ulcer AbbreviationsHDR-ISBTHigh-dose rate interstitial brachytherapy

EQD2Dose in equivalent in 2 Gy fractions

ICBTIntracavitary brachytherapy

ISBTInterstitial brachytherapy

DVHDose volume histogram

EBRTExternal beam radiation therapy

GTVGross tumor volume

CTVClinical target volume

OAROrgan at risk

AUCArea under the curve

ROCReceiver operating characteristics

IGBTImage guided brachytherapy

PDRPulsed dose rate.

Electronic supplementary materialThe online version of this article doi:10.1186-1748-717X-9-31 contains supplementary material, which is available to authorized users.

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Author: Naoya Murakami - Takahiro Kasamatsu - Minako Sumi - Ryoichi Yoshimura - Ken Harada - Mayuka Kitaguchi - Shuhei Sekii - Kana

Source: https://link.springer.com/







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