Prospective multi-center trial utilizing electronic brachytherapy for the treatment of endometrial cancer

A dosimetric comparison of brachytherapy sources for endometrial cancer: an electronic brachytherapy and an iridium-192 source with multichannel cylinders and a three-dimensional technique

BACKGROUND AND PURPOSE

Ir192 vaginal brachytherapy (IBT) is commonly used for patients with postoperative endometrial cancer (EC). We devised a novel multichannel vaginal applicator that could be equipped with an electronic brachytherapy (EBT) device. We aimed to explore the differences in physical parameters between the EBT and IBT.

MATERIALS AND METHODS

This retrospective study included 20 EC patients who received adjuvant IBT from March 1, 2023, to May 1, 2023. Multichannel vaginal cylinders were used, and three-dimensional plans were generated. We designed an electronic multichannel vaginal applicator model and simulated a three-dimensional EBT plan. In order to ensure comparability, D90 of the CTV for the EBT plan was normalized to be equivalent to that of the IBT plan for the same patient.

RESULTS

Twenty EBT plans were compared with 20 IBT plans. Results showed, the mean D90 value of clinical target volume (CTV) was 536.1 cGy for both treatment plans. For the mean dose of CTV, the EBT was significantly greater (738.3 vs. 684.3 cGy, p = 0.000). There was no significant difference in CTV coverage between the EBT and IBT plans. For high-dose areas (V200% and V150%), the EBTs were significantly greater. There were no significant differences in the maximum doses to the vaginal mucosa between the EBT and IBT, whether at the apex or in the middle segment. For the bladder and rectum, both the low-dose area and high-dose area were significantly lower in the EBT plans. For the conformity index, there was no significant difference between the EBT and IBT plans. For the dose homogeneity index, the EBT value was lower.

CONCLUSION

In conclusion, under the premise of a three-dimensional brachytherapy plan, for patients receiving multichannel vaginal applicator brachytherapy, compared with IBT, EBT could reduce the dose to the surrounding organs at risk while maintaining the dose in the target area.

Electronic brachytherapy for gynecological cancers - a systematic review

Background

The purpose of this manuscript is to provide an in-depth literature review of the management of endometrial and cervical cancers with electronic brachytherapy.

Materials and methods

An extensive literature search was performed and 9 articles were selected based on preset criteria.

Results

The reviewed studies provided dosimetric and clinical results. Patient populations were diverse and prescribed doses varied. When treatment plans were compared to those using cobalt 60 (⁶⁰Co) and iridium 192 (¹⁹²Ir) sources researchers found lower or equivalent doses in organs at risk while the doses at the applicator surface were significantly higher for electronic brachytherapy. In the eligible studies, a total of 72 patients received treatment with AxxentXoft vaginal applicator, 29 were treated with the Intrabeam vaginal applicator, and 8 with AxxentXoft cervical applicator.

Conclusions

All authors found that electronic brachytherapy was safe and well tolerated as higher mucosal doses did not present as adverse clinical effects. Electronic brachytherapy for gynecological cancers has the potential to achieve equivalent tumor control while minimizing bowel and urinary toxicity thus improving the quality of life. More clinical data is needed to stratify patients who would benefit the most.

Feasibility and Safety of Intraoperative Radiotherapy with Low Energy X-ray Photon Therapy for Recurrent Gynecological Cancer: A Case Series

Objectives: To evaluate the feasibility and safety of low energy X-ray photon intraoperative radiotherapy (IORT) as an adjuvant therapy for recurrent gynecological cancer.Methods: Medical records of all recurrence gynecological cancer patients who underwent IORT were reviewed. Results: Between January 2018 and December 2021, five women (including cervical cancer (n = 2), endometrial cancer (n = 2), and uterine leiomyosarcoma (n = 1)), who underwent IORT and surgical resection for recurrent gynecologic cancer were reviewed. A median dose of 15.62 Gy (range, 12 to 20 Gy) was used for IORT. Repeated IORT and surgical resection was performed in two women. Three women experienced local recurrence, and three women died during follow-up. The 1-year local control rate was 60%. The 2-year overall survival rate was 30%. There was no Clavien–Dindo classification grade III–V complication. Conclusion: IORT using low energy X-ray photon therapy seems to be feasible and safe as an adjuvant therapy in women who underwent salvage surgery for recurrent gynecologic cancer. However, large-scale prospective studies are needed to confirm our findings and evaluate its efficacy.

Adjuvant electronic brachytherapy for endometrial carcinoma: A 4-year outcomes report

PURPOSE

The purpose of the study was to report the outcomes of a single-center adjuvant electronic brachytherapy (e-BT) experience for patients with endometrial carcinoma.

METHODS AND MATERIALS

Patients were retrospectively assessed. Intracavitary e-BT was applied through a cylindrical applicator (diameters 2.5-3.5 cm). e-BT single doses ranged between 4 and 7 Gy (EQD2 ∼ 6-12, α/β of 10 Gy and an relative biological effectiveness of 1.3) at 5-mm depth. Adverse events are reported at first week, 1-3 months, 3-12 months, 12-24 months, and >24 months. The overall survival, disease-free survival, distant disease control rate, and local control rate were estimated using the Kaplan-Meier method.

RESULTS

Twenty-nine patients were assessed. The median age was 68 [48-86] years. External beam radiotherapy was added in n = 8 (27.6%) patients. Staging was 13.8% for T1a, 51.7% for T1b, 24.1% for T2, 6.9% for T3a, and 3.4% for T3b. Grading was G3 in 51.7% (n = 15), G2 in 20.7% (n = 6), and G1 in 27.6% (n = 8). Median followup was 47 months [5-88]. Overall Grade 1, 2, and 3 toxicity was 89.7% (n = 26), 17.2% (n = 5), and 6.9% (n = 2), respectively. No Grade 3 cystitis or proctitis or any Grade 4 or 5 toxicity occurred during followup. No local recurrences were detected. Estimated distant disease control rate was 92.1% (n = 2, distant metastasis at 7 and 11 months). Estimated 4-year overall survival was 84.8% (n = 4 events, two unrelated to disease) and disease-free survival was 84.6%.

CONCLUSIONS

Our data suggest that e-BT resembles a very-low-toxicity profile and a high local control rate in the adjuvant scenario for patients with endometrial carcinoma.

Postoperative endometrial cancer treatments with electronic brachytherapy source

Purpose

This study is a dosimetric and acute toxicity comparison of endometrial cancer patients treated with either Axxent (Xoft, Inc., San José, CA, USA) electronic and interstitial brachytherapy versus interstitial high dose rate brachytherapy (HDRBT).

Materials and Methods

Between 2015 and 2017, 94 patients with postoperative endometrial cancer were treated in our centre with the Axxent electronic brachytherapy (eBT) system. The V150 and V200 are evaluated prospectively for each plan. The mean age of patients was 65.9 years (age range 33–84 years), with different tumour staging. Of the 94 patients, 37 received exclusive adjuvant brachytherapy (25 Gy in five sessions); the remaining patients received external beam radiotherapy (EBRT) with a regimen of 23 sessions of 2 Gy each to the entire pelvis, followed by eBT (15 Gy in three sessions). Additionally, the absorbed doses received by the organs at risk (OAR), urinary bladder, rectum and sigmoid colon were compared with HDRBT plans, evaluating D2cc, V50% and V35%. Median follow-up was done for each of the 94 patients to assess the toxicity of the treatment: vaginal mucosa toxicity, rectal and urinary toxicity; and results are presented for acute toxicity, toxicity at 1 month after the end of treatment and follow-up after 12 months for a portion of patients according to the Radiation Therapy Oncology Group (RTOG) toxicity criteria.

Results

The doses in OAR for eBT plans were lower than that for HDRBT plans, both Ir-192 and Co-60 plans, whose doses were similar. The dose in bladder with eBT was 63.8% of the prescribed dose for D2cc versus 70.1% for HDRBT Ir-192, for V50% was 7.2% versus 12.7% and for V35% was 15.2% versus 28.2%. In rectum the D2cc was 61.2% versus 68.4%, for V50% was 7.9% versus 14.3% and for V35% was 16.7% versus 32%. Results demonstrated lower doses to OAR in all eBT plans. Acute toxicity in eBT was very low in cases of mucositis, with only one case of toxicity greater than grade 1, rectal toxicity and urinary toxicity; results at 1 month are equally good, toxicity symptoms disappeared and no relapses have occurred to date.

Conclusions

The results of treatment with the Axxent eBT unit for 94 patients are very good, as no recurrence has been observed and the toxicity of the treatment is very low. The increase in V150 and V200 has not produced an increase in vaginal mucosa toxicity, and the doses in the OAR are lower than in the plans implemented for HDRBT with Ir-192 or Co-60. eBT is a good alternative to treat endometrial cancer in centres without conventional HDR availability. To date, there are limited published studies reporting on outcomes from patients treated with eBT.

Clinical and cosmetic outcomes in patients treated with high-dose-rate electronic brachytherapy for nonmelanoma skin cancer

PURPOSE

To retrospectively analyze clinical and cosmetic outcomes in patients treated for nonmelanoma skin cancer (NMSC) with high-dose-rate (HDR) electronic brachytherapy (EBT) using surface applicators.

METHODS AND MATERIALS

We identified 127 patients who had 154 NMSC lesions, 149 of which were basal cell carcinoma, treated with HDR EBT at our institution between July 2012 and March 2014. Lesions were treated to 40 Gy in 8 fractions. Local control, acute toxicity, late toxicity, and cosmetic outcomes were analyzed retrospectively. Acute and late toxicities were graded using the Common Terminology Criteria for Adverse Events, version 4.0. Cosmetic outcomes were graded using a standard scale based on the Radiation Therapy Oncology Group and European Organization for Research and Treatment of Cancer Late Radiation Morbidity Scoring Schema.

RESULTS

Median (range) follow-up from completion of treatment was 16.1 (3.4-34.8 months). The overall crude recurrence rate was 1.3% (n = 2). Grade 0 to 1 acute radiation dermatitis was observed in 52.6% of treated lesions (n = 81), grade 2 in 34.4% (n = 53), and grade 3 in 13.0% (n = 20). No acute toxicity greater than grade 3 was observed and all acute toxic events resolved after treatment. Grade 0 to 1 late toxicity was observed in 94.2% of cases (n = 145), and grade 2 in 5.8% (n = 9). No late toxicity greater than grade 2 was observed. Across the 152 controlled lesions, cosmetic results were excellent in 94.2% of treated lesions (n = 145), good in 3.3% (n = 5), fair in 0.7% (n = 1), and poor in 0.7% (n = 1).

CONCLUSIONS

HDR EBT confers promising local control, minimal toxicity, and excellent cosmesis in our institutional experience. It should be considered ideal for NMSC of the head and neck, particularly for basal cell carcinoma involving central facial locations where surgical cosmesis may be inferior.

Topical KGF treatment as a therapeutic strategy for vaginal atrophy in a model of ovariectomized mice

One of the most frequent complaints for post-menopausal women is vaginal atrophy, because of reduction in circulating oestrogens. Treatments based on local oestrogen administration have been questioned as topic oestrogens can reach the bloodstream, thus leading to consider their safety as controversial, especially for patients with a history of breast or endometrial cancers. Recently, growth factors have been shown to interact with the oestrogen pathway, but the mechanisms still need to be fully clarified. In this study, we investigated the effect of keratinocyte growth factor (KGF), a known mitogen for epithelial cells, on human vaginal mucosa cells, and its potential crosstalk with oestrogen pathways. We also tested the in vivo efficacy of KGF local administration on vaginal atrophy in a murine model. We demonstrated that KGF is able to induce proliferation of vaginal mucosa, and we gained insight on its mechanism of action by highlighting its contribution to switch ERα signalling towards non-genomic pathway. Moreover, we demonstrated that KGF restores vaginal trophism in vivo similarly to intravaginal oestrogenic preparations, without systemic effects. Therefore, we suggest a possible alternative therapy for vaginal atrophy devoid of the risks related to oestrogen-based treatments, and a patent (no. RM2012A000404) has been applied for this study.

Nonmelanoma skin cancer treated with electronic brachytherapy: results at 1 year

PURPOSE

We report clinical outcomes at 1 year or more after high-dose-rate (HDR) electronic brachytherapy (EBT) using surface applicators for the treatment of nonmelanoma skin cancer (NMSC).

METHODS AND MATERIALS

From July 2009 to April 2012, 122 patients with 171 NMSC lesions were treated with EBT to a dose of 40Gy in eight fractions, delivered twice weekly. At followup, patients were assessed for acute and late toxicities, cosmesis, and local control.

RESULTS

Treatment of 171 lesions was completed in 122 patients with a mean age 73 years. There have been no recurrences to date with a mean followup of 10 months (range, 1-28 months). Followup data at 1 year or more were available for 46 lesions in 42 patients. Hypopigmentation (all Grade 1) was present in 5 (10.9%) of 46 lesions at 1 year. Other late effects at 1 year included dry desquamation, alopecia, and rash dermatitis, which occurred in 1 (2.2%), 1 (2.2%), and 3 (6.5%) of 46 lesions, respectively. No Grade 3 or higher adverse events were observed at any time point. Cosmesis was evaluated at 1 year for 42 of 46 lesions and was excellent for 39 (92.9%) and good for 3 (7.1%) of the 42 evaluable lesions.

CONCLUSIONS

Treatment of NMSC with HDR EBT using surface applicators was effective with no recurrences, good to excellent cosmesis, and acceptable toxicities at 1 year or more after treatment. HDR EBT provides a convenient nonsurgical treatment option for NMSC patients.

Adjuvant radiotherapy for stage I endometrial cancer

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 2, 2007. The role of radiotherapy (both pelvic external beam radiotherapy (EBRT) and vaginal intracavity brachytherapy (VBT)) in stage I endometrial cancer following hysterectomy remains controversial.

OBJECTIVES

To assess the efficacy of adjuvant radiotherapy following surgery for stage I endometrial cancer.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Specialised Register to end-2005 for the original review, and extended the search to January 2012 for the update.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared post-operative adjuvant radiotherapy (either EBRTor VBT, or both) versus no radiotherapy or VBT in women with stage I endometrial cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials and extracted data to a specifically designed data collection form. The primary outcome was overall survival. Secondary outcomes were endometrial cancer-related deaths, locoregional recurrence and distant recurrence. Meta-analyses were performed using Cochrane Review Manager Software 5.1.

MAIN RESULTS

We included eight trials. Seven trials (3628 women) compared EBRT with no EBRT (or VBT), and one trial (645 women) compared VBTwith no additional treatment. We considered six of the eight trials to be of a high quality. Time-to-event data were not available for all trials and all outcomes.EBRT (with or without VBT) compared with no EBRT (or VBT alone) for stage I endometrial carcinoma significantly reduced locoregional recurrence (time-to-event data: five trials, 2965 women; Hazard Ratio (HR) 0.36, 95% Confidence Interval (CI) 0.25 to 0.52; and dichotomous data: seven trials, 3628 women; Risk Ratio (RR) 0.33, 95% CI 0.23 to 0.47). This reduced risk of locoregional recurrence did not translate into improved overall survival (time-to-event data: five trials, 2,965 women; HR 0.99, 95% CI 0.82 to1.20; and dichotomous data: seven trials, 3628 women; RR 0.98, 95% CI 0.83 to 1.15) or improved endometrial cancer-related survival (time-to-event data: five trials, 2965 women; HR 0.96, 95% CI 0.72 to 1.28; and dichotomous data: seven trials, 3628 women; RR 1.02, 95% CI 0.81 to 1.29) or improved distant recurrence rates (dichotomous data: seven trials, 3628 women; RR 1.04, 95% CI 0.80 to 1.35).EBRT did not improve survival outcomes in either the intermediate-risk or high-risk subgroups, although high-risk data were limited, and a benefit of EBRT for high-risk women could not be excluded. One trial (PORTEC-2) compared EBRT with VBT in the high-intermediate risk group and reported that VBT was effective in ensuring vaginal control with a non-significant difference in loco-regional relapse rate compared to EBRT (5.1% versus 2.1%; HR 2.08, 95% CI 0.71 to 6.09; P = 0.17). In the subgroup of low-risk patients (IA/B and grade 1/2), EBRT increased the risk of endometrial carcinoma-related deaths (including treatment-related deaths) (two trials, 517 women; RR 2.64, 95% CI 1.05 to 6.66) but there was a lack of data on overall survival. We considered the evidence for the low-risk subgroup to be of a low quality.EBRT was associated with significantly increased severe acute toxicity (two trials, 1328 patients, RR 4.68, 95% CI 1.35 to 16.16), increased severe late toxicity (six trials, 3501 women; RR 2.58, 95% CI 1.61 to 4.11) and significant reductions in quality of life scores and rectal and bladder function more than 10 years after randomisation (one trial, 351 women) compared with no EBRT.One trial of VBT versus no additional treatment in women with low-risk lesions reported a non-significant reduction in locoregional recurrence in the VBT group compared with the no additional treatment group (RR 0.39, (95% CI 0.14 to 1.09). There were no significant differences in survival outcomes in this trial.

AUTHORS' CONCLUSIONS

EBRT reduces the risk of locoregional recurrence but has no significant impact on cancer-related deaths or overall survival. It is associated with significant morbidity and a reduction in quality of life. There is no demonstrable survival advantage from adjuvant EBRT for high-risk stage I endometrial cancer, however, the meta-analyses of this subgroup were underpowered and also included high-intermediate risk women, therefore we cannot exclude a small benefit in the high-risk subgroup. EBRT may have an adverse effect on endometrial cancer survival when used to treat uncomplicated low-risk (IA/B grade 1/2) endometrial cancer. For the intermediate to high-intermediate risk group, VBT alone appears to be adequate in ensuring vaginal control compared to EBRT. Further research is needed to guide practice for lesions that are truly high risk. In addition, the definitions of risk should be standardised.

Adjuvant radiotherapy for stage I endometrial cancer

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 2, 2007. The role of radiotherapy (both pelvic external beam radiotherapy (EBRT) and vaginal intracavity brachytherapy (VBT)) in stage I endometrial cancer following hysterectomy remains controversial.

OBJECTIVES

To assess the efficacy of adjuvant radiotherapy following surgery for stage I endometrial cancer.

SEARCH METHODS

We searched The Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Specialised Register to end-2005 for the original review, and extended the search to January 2012 for the update.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that compared post-operative adjuvant radiotherapy (either EBRT or VBT, or both) versus no radiotherapy or VBT in women with stage I endometrial cancer.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials and extracted data to a specifically designed data collection form. The primary outcome was overall survival. Secondary outcomes were endometrial cancer-related deaths, locoregional recurrence and distant recurrence. Meta-analyses were performed using Cochrane Review Manager Software 5.1.

MAIN RESULTS

We included eight trials. Seven trials (3628 women) compared EBRT with no EBRT (or VBT), and one trial (645 women) compared VBT with no additional treatment. We considered six of the eight trials to be of a high quality. Time-to-event data were not available for all trials and all outcomes.EBRT (with or without VBT) compared with no EBRT (or VBT alone) for stage I endometrial carcinoma significantly reduced locoregional recurrence (time-to-event data: five trials, 2965 women; Hazard Ratio (HR) 0.36, 95% Confidence Interval (CI) 0.25 to 0.52; and dichotomous data: seven trials, 3628 women; Risk Ratio (RR) 0.33, 95% CI 0.23 to 0.47). This reduced risk of locoregional recurrence did not translate into improved overall survival (time-to-event data: five trials, 2,965 women; HR 0.99, 95% CI 0.82 to 1.20; and dichotomous data: seven trials, 3628 women; RR 0.98, 95% CI 0.83 to 1.15) or improved endometrial cancer-related survival (time-to-event data: five trials, 2965 women; HR 0.96, 95% CI 0.72 to 1.28; and dichotomous data: seven trials, 3628 women; RR 1.02, 95% CI 0.81 to 1.29) or improved distant recurrence rates (dichotomous data: seven trials, 3628 women; RR 1.04, 95% CI 0.80 to1.35).EBRT did not improve survival outcomes in either the intermediate-risk or high-risk subgroups, although high-risk data were limited, and a benefit of EBRT for high-risk women could not be excluded. In the subgroup of low-risk patients (IA/B and grade 1/2), EBRT increased the risk of endometrial carcinoma-related deaths (including treatment-related deaths) (two trials, 517 women; RR 2.64, 95% CI 1.05 to 6.66) but there was a lack of data on overall survival. We considered the evidence for the low-risk subgroup to be of a low quality.EBRT was associated with significantly increased severe acute toxicity (two trials, 1328 patients, RR 4.68, 95% CI 1.35 to 16.16), increased severe late toxicity (six trials, 3501 women; RR 2.58, 95% CI 1.61 to 4.11) and significant reductions in quality of life scores and rectal and bladder function more than 10 years after randomisation (one trial, 351 women) compared with no EBRT.One trial of VBT versus no additional treatment in women with low-risk lesions reported a non-significant reduction in locoregional recurrence in the VBT group compared with the no additional treatment group (RR 0.39, (95% CI 0.14 to 1.09). There were no significant differences in survival outcomes in this trial.

AUTHORS' CONCLUSIONS

EBRT reduces the risk of locoregional recurrence but has no significant impact on cancer-related deaths or overall survival. It is associated with significant morbidity and a reduction in quality of life, and bladder and rectal function. EBRT may have an adverse effect on endometrial cancer survival when used to treat uncomplicated low-risk (IA/B grade 1/2) endometrial cancer. There is no demonstrable survival advantage from adjuvant EBRT for high-risk stage I endometrial cancer, however, the meta-analyses of this subgroup were underpowered and also included high-intermediate risk women. Further research is likely to have an important impact on our confidence in the estimates of effects and may change the estimates. Therefore, whilst there appears to be no survival benefit in the routine use of EBRT in women with stage I endometrial cancer, we cannot exclude a benefit in high-risk women. VBT is potentially useful in intermediate-risk and high-risk subgroups but evidence from further RCTs is needed. In addition, the definitions of risk should be standardised.

Sequential chemotherapy and radiotherapy as sandwich therapy for the treatment of high risk endometrial cancer

Objective

The purpose of this retrospective study was to assess the tolerability and efficacy of sequential chemotherapy and radiotherapy for the treatment of high risk endometrial cancer.

Methods

We conducted a retrospective study of previously untreated high risk endometrial cancer patients who received sequential chemotherapy and radiotherapy in accordance with the sandwich approach from June 2008 until June 2011. High risk endometrial cancer patients underwent complete surgical staging followed by adjuvant therapy encompassing sequential chemotherapy, radiation therapy and consolidation chemotherapy.

Results

The study analysis comprised 32 endometrial cancer patients. All subjects were treated with carboplatin and paclitaxel chemotherapy; currently, 186 cycles have been administered and 94% of patients have completed the planned number of cycles. Grade 3 neutropenia developed in 1 (3.1%) patient; there was no incidence of grade 4 neutropenia. Moreover, we observed grade 3 anemia in four (12.5%) patients and grade 4 anemia in one (3.1%) patient. One (3.1%) patient developed grade 3 thrombocytopenia; grade 4 thrombocytopenia was not observed. Five patients exhibited progressive disease, three of whom have since expired; mean progression free survival and follow-up were 17.4 months and 18.9 months, respectively.

Conclusion

The preliminary results from our study suggest that the sandwich approach to treating high risk endometrial cancer patients is feasible. Hematologic toxicity was well tolerated and non-hematologic toxicity was mild and easily managed. Further study of this novel regimen in a larger patient population with extended follow-up is necessary.

Endometrial cancer - reduce to the minimum. A new paradigm for adjuvant treatments?

BACKGROUND

Up to now, the role of adjuvant radiation therapy and the extent of lymph node dissection for early stage endometrial cancer are controversial. In order to clarify the current position of the given adjuvant treatment options, a systematic review was performed.

MATERIALS AND METHODS

Both, Pubmed and ISI Web of Knowledge database were searched using the following keywords and MESH headings: "Endometrial cancer", "Endometrial Neoplasms", "Endometrial Neoplasms/radiotherapy", "External beam radiation therapy", "Brachytherapy" and adequate combinations.

CONCLUSION

Recent data from randomized trials indicate that external beam radiation therapy - particularly in combination with extended lymph node dissection - or radical lymph node dissection increases toxicity without any improvement of overall survival rates. Thus, reduced surgical aggressiveness and limitation of radiotherapy to vaginal-vault-brachytherapy only is sufficient for most cases of early stage endometrial cancer.

A comparison of the biological effective dose of 50-kV electronic brachytherapy with (192)Ir high-dose-rate brachytherapy for vaginal cuff irradiation

PURPOSE

Advantages for electronic brachytherapy (EBT) of the vaginal cuff include decreased physical dose to the bladder and rectum. Here we compare (192)Ir with EBT using biological effective dose (BED) to account for the different radiobiological effectiveness (RBE) predicted for low-energy x-rays.

METHODS AND MATERIALS

Fifteen data sets from five consecutive postoperative endometrial cancer patients treated with EBT were analyzed. Treatment planning was performed using PLATO software. The dose was prescribed as 21Gy in three fractions to a depth of 0.5cm. Physical dose, BED(3), and BED(10) were evaluated for the mucosa, bladder, and rectum. An RBE value of 1.5 was used for BED calculations.

RESULTS

Mucosal physical dose is 28.4% greater with EBT (36.6 vs. 28.5Gy, p<0.05). However, the BED(10) is increased by 79.1% (55.6 vs. 99.6Gy, p<0.05) and the BED(3) by 71.5% (118.8 vs. 203.7Gy, p<0.05). The physical dose (dose to 50% volume of the organ) to the bladder (9.3 vs. 6.6Gy, p<0.05) and rectum (7.2 vs. 4.2Gy, p<0.05) are reduced with EBT. BED(3) to the rectum and bladder are also reduced but to a lesser extent (13 vs. 8.3Gy, p<0.05; 18.9 vs. 14.7Gy, p=0.06, respectively).

CONCLUSIONS

BED takes into account the higher RBE of low-energy photons generated with EBT and provides a more accurate estimate of the biological effect. When using EBT, physical dose may underestimate the biological effect on the vaginal mucosa and overestimate the benefit for the bladder and rectum. Dose adjustment for EBT based on BED should be considered.

Use of electronic brachytherapy to deliver postsurgical adjuvant radiation therapy for endometrial cancer: a retrospective multicenter study

BACKGROUND

This retrospective, multicenter study evaluated the feasibility and safety of high-dose rate electronic brachytherapy (EBT) as a postsurgical adjuvant radiation therapy for endometrial cancer.

METHODS

Medical records were reviewed from 41 patients (age 40-89 years) with endometrial cancer (Federation of International Gynecology and Obstetrics stages IA-IIIC) treated at nine centers between April 2008 and October 2009. Treatment included intracavitary vaginal EBT alone (n = l6) at doses of 18.0-24.0 Gy in 3-4 fractions and EBT in combination with external beam radiation therapy (EBRT, n = 25) at a total radiation dose range of 40.0-80.4 Gy. Doses were prescribed to a depth of 5 mm from the applicator surface and to the upper third (n = 15) and the upper half (n = 26) of the vagina.

RESULTS

Median follow-up was 3.8 (range 0.5-12.0) months. All 41 patients received the intended dose of radiation as prescribed. Adverse events occurred in 13 of 41 patients and were mild to moderate (Grade 1-2), consisting primarily of vaginal mucositis, rectal mucosal irritation and discomfort, and temporary dysuria and diarrhea. There were no Grade 3 adverse events in the EBT-only treatment group. One patient, who was being treated with the combination of EBT and EBRT for recurrent endometrial cancer, had a Grade 3 adverse event. No recurrences have been reported to date.

CONCLUSION

Electronic brachytherapy provides a feasible treatment option for postoperative adjuvant vaginal brachytherapy as sole radiation therapy and in combination with EBRT for primary endometrial cancer. Early and late toxicities were mild to moderate.