Clinical outcomes and dosimetric predictors of toxicity for re-irradiation of vaginal recurrence of endometrial cancer.

OBJECTIVE: To report clinical outcomes and dosimetric predictors of late toxicity for patients with vaginal recurrence of endometrial cancer treated with brachytherapy in the re-irradiation setting. METHODS: On retrospective review, 32 patients with vaginal recurrence of endometrial cancer received salvage brachytherapy with or without pelvic radiotherapy (RT) from 06/2003-12/2017. Prior RT modalities were vaginal brachytherapy (19, 59%), pelvic RT (7, 22%) or both (6, 19%). Image-guided brachytherapy was performed with CT- (25, 78%) or MR-guidance (7, 22%). Vaginal control, recurrence-free survival (RFS) and overall survival (OS) were estimated by Kaplan-Meier method. Late toxicity was graded by Common Toxicity Criteria for Adverse Events. RESULTS: Median time from prior RT to re-irradiation was 22 months (range, 4-140). Salvage RT modalities were pelvic RT and brachytherapy (25, 78%) or brachytherapy alone (7, 22%). With median follow-up of 47 months, 3/5-year vaginal control, RFS and OS rates were 64/56%, 47/41% and 68/42%, respectively. Six patients (19%) had no evidence of disease at 85-155 months. Late grade 2/3 GI, GU and vaginal toxicity rates were 13%/16%, 19%/13%, and 9%/16%. Cumulative D2cc rectum (sum of prior and salvage RT courses) was predictive of grade 2+ and grade 3 GI toxicity. Cumulative D2cc rectum for an estimated 10% risk of late grade 2+ and 3 GI toxicity was 86 Gy and 92 Gy, respectively. CONCLUSIONS: Salvage image-guided brachytherapy in the re-irradiation setting results in modest local control and increased late toxicity for localized recurrent endometrial cancer. With long-term disease control, cumulative D2cc rectum may be used to reduce late GI complication risk.

Adjuvant Radiation Field Extent and Sites of Failure in Node Positive Endometrioid Endometrial Cancer.

PURPOSE: In patients with node-positive endometrial cancer, adjuvant radiation therapy with chemotherapy decreases local-regional recurrence compared with chemotherapy alone. However, the optimal radiation field borders and extent of nodal coverage have not been well studied. In a multi-institutional cohort, survival outcomes and sites of failure were analyzed for patients with International Federation of Gynaecology and Obstetrics (FIGO) stage IIIC endometrioid endometrial cancer treated with pelvic radiation therapy (PRT) versus extended-field radiation therapy (EFRT), which encompassed high para-aortic lymph nodes. METHODS AND MATERIALS: In a multi-institutional retrospective study, 143 patients with FIGO stage IIIC1 or IIIC2 endometrioid endometrial cancer treated with adjuvant radiation therapy from 2000 to 2016 were identified. Patient subgroups were classified by substage and radiation field extent: stage IIIC1 received EFRT, stage IIIC1 received PRT, and stage IIIC2 received EFRT. Recurrence-free survival (RFS), overall survival (OS), and out-of-field recurrence were calculated by the Kaplan-Meier method. Multivariate analysis was performed using the Cox proportional hazards model. Sites of failure were categorized as within or outside the radiation field. RESULTS: The median follow-up was 59 months; 87% of patients received chemotherapy. The 5-year RFS and OS rates were 73% and 87%, respectively. By subgroup, 5-year RFS rates were 79% for stage IIIC1 EFRT, 73% for stage IIIC1 PRT, and 69% for stage IIIC2 EFRT (P = .4). On multivariate analysis, the recurrence risk was highest for stage IIIC2 EFRT, although this result was not statistically significant (adjusted hazard ratio, 2.0; P = .4). In-field vaginal and nodal recurrences were observed in 2 patients (1%) and 4 patients (3%), respectively. Of 78 patients with stage IIIC1 cancer treated with PRT, 5 (6%) had isolated para-aortic nodal relapse outside the radiation field; 3 were long-term survivors (more than 6 years after salvage therapy). For patients with para-aortic recurrence, 86% had lymphovascular invasion, 71% had myometrial invasion of ≥50%, and 57% had grade 3 disease. CONCLUSIONS: Adjuvant chemoradiation therapy resulted in excellent survival outcomes for patients with FIGO stage IIIC endometrioid endometrial cancer. For patients with positive pelvic nodes, isolated para-aortic relapse outside the PRT field was uncommon and amenable to salvage therapy.

Low-Dose Adjuvant Cylinder Brachytherapy for Endometrioid Endometrial Cancer.

PURPOSE: Our purpose was to evaluate outcomes and sites of failure for women with early stage endometrial adenocarcinoma treated with adjuvant high-dose-rate (HDR) vaginal brachytherapy (VB) with a low dose scheme. METHODS AND MATERIALS: Retrospective review identified 318 patients with International Federation of Gynecology and Obstetrics (FIGO) stage I-II endometrioid endometrial cancer who received adjuvant HDR VB to a dose of 24 Gray (Gy) in 6 fractions from 2005 to 2017. Patients with <6 months follow-up were excluded. Dose was prescribed to cylinder surface and computerized tomography (CT) imaging was performed before each fraction to assess cylinder placement. Rates of vaginal relapse (VR), pelvic nodal relapse, distant metastasis, recurrence-free survival, and overall survival were calculated by Kaplan-Meier method. Univariate analysis was performed by log rank test or Cox proportional hazards. Pretreatment CT images were analyzed for patients with VR. RESULTS: Median follow-up was 42 months for 243 patients. The 3-year rates of VR, pelvic nodal relapse, distant metastasis, recurrence-free survival, and overall survival were 1.9%, 1.5%, 4.3%, 94.1%, and 98.9%, respectively. The 3-year VR rates by Gynecologic Oncology (GOG)-99 risk groups were 0%, 1.4%, and 3.2% for low risk, low-intermediate risk, and high-intermediate risk (HIR) disease (P = .5). By Post-operative Radiation Therapy in Endometrial Carcinoma (PORTEC) risk stratification, 3-year VR rate was 1.3% for HIR disease. On review of pretreatment CT images of the 6 patients with VR, 3 patients had relapse at the introitus outside of the treated vaginal length, and 3 had in-field recurrence at the vaginal apex. Higher body mass index (BMI) was associated with VR, with a 14% increase in risk per BMI unit (kg/m2, P = .02). There were no reported grade 2 GI or any grade 3 toxicities. CONCLUSIONS: Adjuvant HDR VB with a low-dose regimen results in excellent clinical outcomes for patients with early stage endometrioid endometrial cancer. Patients with higher BMI may be at increased risk of VR, and additional study is needed to optimize brachytherapy treatment parameters.