GEC-ESTRO multicenter phase 3-trial: Accelerated partial breast irradiation with interstitial multicatheter brachytherapy versus external beam whole breast irradiation: Early toxicity and patient compliance

Very accelerated partial breast irradiation in 1 or 2 days: Late toxicity and early oncological outcome of the GEC-ESTRO VAPBI cohort

PURPOSE

To analyze late toxicity after very accelerated partial breast irradiation (VAPBI) for low-risk breast cancer.

MATERIALS

Methods: In this retrospective, observational, international multicenter study (HDH F20220713143949), patients with low-risk breast cancer underwent lumpectomy + vAPBI (high-dose rate multicatheter interstitial brachytherapy-MIBT). VAPBI was performed with 4(4x6.2 Gy/2d), 3(3x7.45 Gy/2d) or 1 fraction (1x16Gy or 1x18Gy/1d). Primary endpoint was late toxicity. Secondary endpoints were cumulative incidence of breast cancer local relapse (LR) and distant metastatic relapse (DMR) and specific (SS) and overall (OS) survivals. Prognostic factors for late toxicity were analyzed.

RESULTS

From 01/2012 to 06/2022, 516 pts with early breast cancer were enrolled. Median follow-up was 44 months [95 %CI 39-46]. Median age was 71 years [40-100]. Median tumor size was 12 mm [1-35]. VAPBI delivered 1, 3 and 4 fractions for 205pts (39.7 %), 167pts (32.4 %) and 144pts (28 %) respectively. 221 late toxicity events were observed in 168pts (32.6 %) (Fibrosis, dyschromia, pain and telangiectasia). Grade 2 and 3 late toxicities were observed in 7.2 and 0.6 % respectively (no G4) with no difference between 1 and ≥ 2 treatment days. CTV > 50 cc (p = 0.007) and V150 > 40 % (p = 0.027) were prognostic factors for G ≥ 2 late toxicity. Four-year cumulative incidence rates of LR and DMR were 2 % [95 %CI 0-3] and 1 % [95 %CI 0-2] respectively.

CONCLUSIONS

VAPBI based on 1 or ≥ 2 days of MIBT represents an attractive de-escalation of irradiation approach for low-risk breast cancer. Late toxicity profile appears acceptable while early oncological outcome shows encouraging local control. Longer follow-up is warranted in order to confirm these preliminary results.

Brachytherapy on-a-chip: a clinically-relevant approach for radiotherapy testing in 3d biology

We describe the first microfluidic device for in vitro testing of brachytherapy (BT), with applications in translational cancer research. Our PDMS-made BT-on-chip system allows highly precise manual insertion of clinical BT seeds, reliable dose calculation using standard clinically-used TG-43 formalism and easy culture of naturally hypoxic spheroids in less than 3 days, thereby increasing the translational potential of the device. As the BT-on-chip platform is designed to be versatile, we showcase three different gold-standard post-irradiation bioassays and recapitulate, for the first time on-chip, key clinical observations such as dose rate effect and hypoxia-induced radioresistance. Our results suggest that BT-on-chip can be used to safely and efficiently integrate BT and radiotherapy to translational research and drug development pipelines, without expensive equipment or complex workflows.

Partial-accelerated irradiation with stereotactic radiotherapy at a dose of 30 Gy in 5 fractions in early breast cancer

PURPOSE

To evaluate feasibility of accelerated partial breast irradiation (APBI) using stereotactic radiotherapy (SBRT) Thirty Gy delivered in 5 fractions for patients with early breast cancer.

METHODS

Between January 1st, 2018, and December 31s, 2022, we conducted 117 treatments for patients with early-stage breast cancer. All patients underwent conservative surgery followed by APBI using stereotactic external beam radiotherapy. We analyzed local, regional, distant control, overall survival, toxicity, and cosmetic outcomes.

RESULTS

The average age was 62 years. 21.3% ductal and 78.7% invasive carcinomas. Regarding the PTV volume, the median was 198.8 cc (38-794 cc). Treatments were completed in all cases. The median follow-up period was of 21 months (1-62 months). Regarding acute toxicity, no Grade 3-4 toxicities were recorded. One patient experienced Grade 2 neuropathic pain. One patient developed subacute fibrosis and two patients developed telangiectasia as subacute and chronic toxicity. Cosmetic results were "good" or "very good" in 96.3% of cases. None of the patients relapsed at any level (local, regional, or distant) and overall survival during follow.up was 100%.

CONCLUSION

APBI with SBRT 30 Gy in 5 fractions in early-stage breast cancer is a feasible technique, very-well tolerated and has excellent oncologic and cosmetic outcome during our follow-up period.

Toxicity of external beam accelerated partial-breast irradiation (APBI) in adjuvant therapy of early-stage breast cancer: prospective randomized study

BACKGROUND

Accelerated partial breast irradiation (APBI) is an alternative breast-conserving therapy approach where radiation is delivered in less time compared to whole breast irradiation (WBI), resulting in improved patient convenience, less toxicity, and cost savings. This prospective randomized study compares the external beam APBI with commonly used moderate hypofractionated WBI in terms of feasibility, safety, tolerance, and cosmetic effects.

METHODS

Early breast cancer patients after partial mastectomy were equally randomized into two arms- external APBI and moderate hypofractionated WBI. External beam technique using available technical innovations commonly used in targeted hypofractionated radiotherapy to minimize irradiated volumes was used (cone beam computed tomography navigation to clips in the tumor bed, deep inspiration breath hold technique, volumetric modulated arc therapy dose application, using flattening filter free beams and the six degrees of freedom robotic treatment couch). Cosmetics results and toxicity were evaluated using questionnaires, CTCAE criteria, and photo documentation.

RESULTS

The analysis of 84 patients with a median age of 64 years showed significantly fewer acute adverse events in the APBI arm regarding skin reactions, local and general symptoms during a median follow-up of 37 months (range 21-45 months). A significant difference in favor of the APBI arm in grade ≥ 2 late skin toxicity was observed (p = 0.026). Late toxicity in the breast area (deformation, edema, fibrosis, and pain), affecting the quality of life and cosmetic effect, occurred in 61% and 17% of patients in WBI and APBI arms, respectively. The cosmetic effect was more favorable in the APBI arm, especially 6 to 12 months after the radiotherapy.

CONCLUSION

External APBI demonstrated better feasibility and less toxicity than the standard regimen in the adjuvant setting for treating early breast cancer patients. The presented study confirmed the level of evidence for establishing the external APBI in daily clinical practice.

TRIAL REGISTRATION

NCT06007118.

Comparison of adverse events in partial- or whole breast radiotherapy: investigation of cosmesis, toxicities and quality of life in a meta-analysis of randomized trials

PURPOSE/OBJECTIVE

Adjuvant whole breast radiotherapy and systemic therapy are part of the current evidence-based treatment protocols for early breast cancer, after breast-conserving surgery. Numerous randomized trials have investigated the therapeutic effects of partial breast irradiation (PBI) compared to whole breast irradiation (WBI), limiting the treated breast tissue. These trials were designed to achieve equal control of the disease with possible reduction in adverse events, improvements in cosmesis and quality of life (QoL). In this meta-analysis, we aimed to investigate the differences between PBI and WBI in side effects and QoL.

MATERIAL/METHODS

We performed a systematic literature review searching for randomized trials comparing WBI and PBI in early-stage breast cancer with publication dates after 2009. The meta-analysis was performed using the published event rates and the effect-sizes for available acute and late adverse events. Additionally, we evaluated cosmetic outcomes as well as general and breast-specific QoL using the EORTC QLQ-C30 and QLQ-BR23 questionnaires.

RESULTS

Sixteen studies were identified (n = 19,085 patients). PBI was associated with a lower prevalence in any grade 1 + acute toxicity and grade 2 + skin toxicity (OR = 0.12; 95% CI 0.09-0.18; p < 0.001); (OR = 0.16; 95% CI 0.07-0.41; p < 0.001). There was neither a significant difference in late adverse events between the two treatments, nor in any unfavorable cosmetic outcomes, rated by either medical professionals or patients. PBI-technique using EBRT with twice-daily fractionation schedules resulted in worse cosmesis rated by patients (n = 3215; OR = 2.08; 95% CI 1.22-3.54; p = 0.007) compared to WBI. Maximum once-daily EBRT schedules (n = 2071; OR = 0.60; 95% CI 0.45-0.79; p < 0.001) and IORT (p = 0.042) resulted in better cosmetic results grade by medical professionals. Functional- and symptom-based QoL in the C30-scale was not different between PBI and WBI. Breast-specific QoL was superior after PBI in the subdomains of "systemic therapy side effects" as well as "breast-" and "arm symptoms".

CONCLUSION

The analysis of multiple randomized trials demonstrate a superiority of PBI in acute toxicity as well breast-specific quality of life, when compared with WBI. Overall, late toxicities and cosmetic results were similar. PBI-technique with a fractionation of twice-daily schedules resulted in worse cosmesis rated by patients.

Partial breast irradiation compared with whole breast irradiation: a systematic review and meta-analysis

BACKGROUND

Early-stage breast cancer is among the most common cancer diagnoses. Adjuvant radiotherapy is an essential component of breast-conserving therapy, and several options exist for tailoring its extent and duration. This study assesses the comparative effectiveness of partial-breast irradiation (PBI) compared with whole-breast irradiation (WBI).

METHODS

A systematic review was completed to identify relevant randomized clinical trials and comparative observational studies. Independent reviewers working in pairs selected studies and extracted data. Randomized trial results were pooled using a random effects model. Prespecified main outcomes were ipsilateral breast recurrence (IBR), cosmesis, and adverse events (AEs).

RESULTS

Fourteen randomized clinical trials and 6 comparative observational studies with 17 234 patients evaluated the comparative effectiveness of PBI. PBI was not statistically significantly different from WBI for IBR at 5 years (RR = 1.34, 95% CI = 0.83 to 2.18; high strength of evidence [SOE]) and 10 years (RR = 1.29, 95% CI = 0.87 to 1.91; high SOE). Evidence for cosmetic outcomes was insufficient. Statistically significantly fewer acute AEs were reported with PBI compared with WBI, with no statistically significant difference in late AEs. Data from subgroups according to patient, tumor, and treatment characteristics were insufficient. Intraoperative radiotherapy was associated with higher IBR at 5, 10, and over than 10 years (high SOE) compared with WBI.

CONCLUSIONS

Ipsilateral breast recurrence was not statistically significantly different between PBI and WBI. Acute AEs were less frequent with PBI. This evidence supports the effectiveness of PBI among selected patients with early-stage, favorable-risk breast cancer who are similar to those represented in the included studies.

Whole Breast Irradiation in Comparison to Endocrine Therapy in Early Stage Breast Cancer-A Direct and Network Meta-Analysis of Published Randomized Trials

BACKGROUND

Multiple randomized trials have established adjuvant endocrine therapy (ET) and whole breast irradiation (WBI) as the standard approach after breast-conserving surgery (BCS) in early-stage breast cancer. The omission of WBI has been studied in multiple trials and resulted in reduced local control with maintained survival rates and has therefore been adapted as a treatment option in selected patients in several guidelines. Omitting ET instead of WBI might also be a valuable option as both treatments have distinctly different side effect profiles. However, the clinical outcomes of BCS + ET vs. BCS + WBI have not been formally analyzed.

METHODS

We performed a systematic literature review searching for randomized trials comparing BCS + ET vs. BCS + WBI in low-risk breast cancer patients with publication dates after 2000. We excluded trials using any form of chemotherapy, regional nodal radiation and mastectomy. The meta-analysis was performed using a two-step process. First, we extracted all available published event rates and the effect sizes for overall and breast-cancer-specific survival (OS, BCSS), local (LR) and regional recurrence, disease-free survival, distant metastases-free interval, contralateral breast cancer, second cancer other than breast cancer and mastectomy-free interval as investigated endpoints and compared them in a network meta-analysis. Second, the published individual patient data from the Early Breast Cancer Trialists' Collaborative Group (EBCTCG) publications were used to allow a comparison of OS and BCSS.

RESULTS

We identified three studies, including a direct comparison of BCS + ET vs. BCS + WBI (n = 1059) and nine studies randomizing overall 7207 patients additionally to BCS only and BCS + WBI + ET resulting in a four-arm comparison. In the network analysis, LR was significantly lower in the BCS + WBI group in comparison with the BCS + ET group (HR = 0.62; CI-95%: 0.42-0.92; p = 0.019). We did not find any differences in OS (HR = 0.93; CI-95%: 0.53-1.62; p = 0.785) and BCSS (OR = 1.04; CI-95%: 0.45-2.41; p = 0.928). Further, we found a lower distant metastasis-free interval, a higher rate of contralateral breast cancer and a reduced mastectomy-free interval in the BCS + WBI-arm. Using the EBCTCG data, OS and BCSS were not significantly different between BCS + ET and BCS + WBI after 10 years (OS: OR = 0.85; CI-95%: 0.59-1.22; p = 0.369) (BCSS: OR = 0.72; CI-95%: 0.38-1.36; p = 0.305).

CONCLUSION

Evidence from direct and indirect comparison suggests that BCS + WBI might be an equivalent de-escalation strategy to BCS + ET in low-risk breast cancer. Adverse events and quality of life measures have to be further compared between these approaches.

External-Beam-Accelerated Partial-Breast Irradiation Reduces Organ-at-Risk Doses Compared to Whole-Breast Irradiation after Breast-Conserving Surgery

In order to evaluate organ-at-risk (OAR) doses in external-beam-accelerated partial-breast irradiation (APBI) compared to standard whole-breast irradiation (WBI) after breast-conserving surgery. Between 2011 and 2021, 170 patients with early breast cancer received APBI within a prospective institutional single-arm trial. The prescribed dose to the planning treatment volume was 38 Gy in 10 fractions on 10 consecutive working days. OAR doses for the contralateral breast, the ipsilateral, contralateral, and whole lung, the whole heart, left ventricle (LV), and the left anterior descending coronary artery (LAD), and for the spinal cord and the skin were assessed and compared to a control group with real-world data from 116 patients who underwent WBI. The trial was registered at the German Clinical Trials Registry, DRKS-ID: DRKS00004417. Compared to WBI, APBI led to reduced OAR doses for the contralateral breast (0.4 ± 0.6 vs. 0.8 ± 0.9 Gy, p = 0.000), the ipsilateral (4.3 ± 1.4 vs. 9.2 ± 2.5 Gy, p = 0.000) and whole mean lung dose (2.5 ± 0.8 vs. 4.9 ± 1.5 Gy, p = 0.000), the mean heart dose (1.6 ± 1.6 vs. 1.7 ± 1.4 Gy, p = 0.007), the LV V23 (0.1 ± 0.4 vs. 1.4 ± 2.6%, p < 0.001), the mean LAD dose (2.5 ± 3.4 vs. 4.8 ± 5.5 Gy, p < 0.001), the maximum spinal cord dose (1.5 ± 1.1 vs. 4.5 ± 5.7 Gy, p = 0.016), and the maximum skin dose (39.6 ± 1.8 vs. 49.1 ± 5.8 Gy, p = 0.000). APBI should be recommended to suitable patients to minimize the risk of secondary tumor induction and the incidence of consecutive major cardiac events.

Preliminary outcomes of accelerated partial breast irradiation by interstitial multicatheter brachytherapy with intraoperative free-hand catheter implantation in early breast cancer

BACKGROUND

To evaluate the clinical feasibility of interstitial brachytherapy by intraoperative free-hand catheter implantation in the treatment of early breast cancer after breast-conserving surgery (BCS).

METHODS

Between January 2018 and December 2019, 44 patients with early breast cancer after BCS who met the inclusion criteria ≥45 years old, invasive carcinoma ≤3 cm or ductal carcinoma in situ <2.5 cm, estrogen receptor positive, lymph node negative, surgical margin negative, no distant metastasis, and an ECOG performance score ≤1 were enrolled in this phase II single-arm study. The postoperative irradiation field includes the tumor bed plus 2-cm margin in all directions, except in the anterior-posterior direction. The total prescribed tumor dose was 3400 cGy delivered in 10 fractions twice daily at 6-hour intervals. The primary endpoints were acute side effects, late treatment-related toxicity, and cosmetic outcome. The secondary endpoints were local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), distant metastasis-free survival (DMFS), and overall survival (OS).

RESULTS

The median follow-up time was 33.5 months (mean, 32.9 months; range, 20-43 months). The cosmetic results were good to very good in 92.3% of the questionnaire respondents. The acute toxicities were mild, and no acute grade 3-4 toxicity was noted. Wound infection was noted in two patients (4.5%). There was only one event of regional lymph node recurrence in one patient. The 3-year LRFS, DMFS, and OS were 100%, and RRFS was 94.7%. For two patients who had a positive lymph node based on their final pathology reports, postoperative irradiation, including whole breast and regional lymph nodes, was added.

CONCLUSION

Accelerated partial breast irradiation using interstitial brachytherapy with the intraoperative free-hand catheter implantation technique provides an alternative method of postoperative radiotherapy for selected patients with early breast cancer after BCS with acceptable toxicities.

DCIS: When is accelerated partial breast irradiation an option? A meta-analysis on outcomes and eligibility

BACKGROUND

The natural history of DCIS may not be progression to invasive breast cancer (IBC). Accelerated partial breast irradiation (APBI) has emerged as an alternative to whole breast radiotherapy (WBRT). The purpose of this study was to assess the impact of APBI on DCIS patients.

MATERIALS AND METHODS

Eligible studies from 2012 to 2022 were identified in PubMed, Cochrane Library, ClinicalTrials, and ICTRP. A meta-analysis was done comparing recurrence rates, breast-related mortality rates, and adverse events of APBI versus WBRT. A subgroup analysis of 2017 ASTRO Guidelines "Suitable" and "Unsuitable" groups was performed. Forest plots and quantitative analysis were done.

RESULTS

Six studies were eligible (3 on APBI versus WBRT, 3 on APBI suitability). All had a low risk of bias and publication bias. The cumulative incidence was the following for APBI and WBRT respectively: IBTR was 5.7% and 6.3% with odds ratio of 1.09, 95% CI [0.84, 1.42], mortality rate was 4.9% and 5.05%, and adverse events was 48.87% and 69.63%. All had no statistical significance between groups. Adverse events were found to favor the APBI arm. Recurrence rate was significantly less in the Suitable group with an odds ratio 2.69, 95% CI [1.56, 4.67], favoring it over the Unsuitable group.

CONCLUSION

APBI was comparable to WBRT in terms of recurrence rate, breast cancer-related mortality rate, and adverse events. APBI was not inferior to WBRT and showed better safety in terms of skin toxicity. Patients classified as suitable for APBI had significantly lesser recurrence rate.

Breast brachytherapy: Building a bright future on the foundation of a rich history of advancement in technology, technique, and patient-centered care

For over 20 years, the concept of accelerated partial breast irradiation (APBI) has received considerable attention. Initially concentrating on the appropriateness of APBI as an alternative treatment to whole breast radiotherapy, investigation and innovation evolved towards dose delivery and technique appropriateness. The purpose of this article is to review the pertinent literature that supports the role brachytherapy serves in delivering APBI and the recognized brachytherapy techniques for dose delivery. Publications establishing techniques utilizing multicatheter brachytherapy, single-entry brachytherapy applicators, permanent breast seed implantation brachytherapy, noninvasive breast brachytherapy and electronic brachytherapy are described. The use of brachytherapy for repeat breast conservation therapy is additionally reviewed. A historical perspective and potential direction of future investigation and innovation are presented.

Cosmetic Results and Side Effects of Accelerated Partial-Breast Irradiation Versus Whole-Breast Irradiation for Low-Risk Invasive Carcinoma of the Breast: The Randomized Phase III IRMA Trial

PURPOSE

The results in terms of side effects vary among the published accelerated partial-breast irradiation (APBI) studies. Here, we report the 5-year results for cosmetic outcomes and toxicity of the IRMA trial.

METHODS

We ran this randomized phase III trial in 35 centers. Women with stage I-IIA breast cancer treated with breast-conserving surgery, age ≥ 49 years, were randomly assigned 1:1 to receive either whole-breast irradiation (WBI) or external beam radiation therapy APBI (38.5 Gy/10 fraction twice daily). Patients and investigators were not masked to treatment allocation. The primary end point was ipsilateral breast tumor recurrence. We hereby present the analysis of the secondary outcomes, cosmesis, and normal tissue toxicity. All side effects were graded with the Radiation Therapy Oncology Group/European Organisation for Research and Treatment of Cancer Radiation Morbidity Scoring Schema. Analysis was performed with both intention-to-treat and as-treated approaches.

RESULTS

Between March 2007 and March 2019, 3,309 patients were randomly assigned to 1,657 WBI and 1,652 APBI; 3,225 patients comprised the intention-to-treat population (1,623 WBI and 1,602 APBI). At a median follow-up of 5.6 (interquartile range, 4.0-8.4) years, adverse cosmesis in the APBI patients was higher than that in the WBI patients at 3 years (12.7% v 9.2%; P = .009) and at 5 years (14% v 9.8%; P = .012). Late soft tissue toxicity (grade ≥ 3: 2.8% APBI v 1% WBI, P < .0001) and late bone toxicity (grade ≥ 3: 1.1% APBI v 0% WBI, P < .0001) were significantly higher in the APBI arm. There were no significant differences in late skin and lung toxicities.

CONCLUSION

External beam radiation therapy-APBI with a twice-daily IRMA schedule was associated with increased rates of late moderate soft tissue and bone toxicities, with a slight decrease in patient-reported cosmetic outcomes at 5 years when compared with WBI, although overall toxicity was in an acceptable range.

A Meta-Analysis of Trials of Partial Breast Irradiation

PURPOSE

Partial breast irradiation (PBI) is the delivery of radiation therapy (RT) limited to the tumor bed after breast conserving surgery. The results of recent trials of PBI compared with whole breast irradiation (WBI) have suggested conflicting results with respect to local control and toxicity. The purpose of this meta-analysis was to assess effectiveness of PBI and to compare the different techniques.

METHODS AND MATERIALS

A meta-analysis of aggregate data from published randomized trials was performed to examine the effectiveness of PBI compared with WBI in patients with invasive breast cancer and ductal carcinoma in situ. Relevant data were extracted. The primary outcome was any ipsilateral breast event (invasive or noninvasive). Secondary outcomes included acute and late toxicity. The results of randomized trials were pooled using a fixed effects model and the inverse variance method.

RESULTS

Fifteen trials involving 16,474 patients were identified. The majority of enrolled patients were >60 years of age and had T1N0 grade 1 to 2 disease treated with hormone therapy. The percent of ipsilateral breast events was higher in patients treated with PBI compared with WBI (5.0% vs 2.8%; risk ratio [RR], 1.72; 95% confidence interval [CI], 1.47-2.02). Heterogeneity (P = .0002) was observed between the 4 PBI techniques: external beam RT without computed tomography (CT) planning (RR, 2.06; 95% CI, 1.36-3.12); brachytherapy (RR, 1.21; 95% CI, 0.65-2.25); intraoperative RT (RR, 2.79; 95% CI, 2.08-3.73); and external beam RT with CT planning (RR, 1.25; 95% CI, 0.99-1.58). When external beam RT without CT planning and intraoperative RT trials were excluded, the percent of ipsilateral breast events was 3.3% versus 2.6%, respectively (RR, 1.25; 95% CI, 1.00-1.55; P = .05), and no heterogeneity was observed (P = .92). Overall, acute toxicity was less with PBI, and the effect on late toxicity varied by technique.

CONCLUSIONS

Overall, WBI was more effective than PBI, but the effectiveness of PBI was technique related. PBI was less effective when given by external beam RT without CT planning or intraoperative therapy. Although PBI given by multicatheter brachytherapy or external beam RT with CT planning tended to be statistically less effective than WBI, the absolute difference between groups for ipsilateral breast events was very small (<1%), supporting these approaches for women considering PBI.

Intraoperative electron radiotherapy in early invasive ductal breast cancer: 6-year median follow-up results of a prospective monocentric registry

Background

Intraoperative electron radiotherapy (IOERT) can be used to treat early breast cancer during the conservative surgery thus enabling shorter overall treatment times and reduced irradiation of organs at risk. We report on our first 996 patients enrolled prospectively in a registry trial.

Methods

At Jules Bordet Institute, from February 2010 onwards, patients underwent partial IOERT of the breast. Women with unifocal invasive ductal carcinoma, aged 40 years or older, with a clinical tumour size ≤ 20 mm and tumour-free sentinel lymph node (on frozen section and immunohistochemical analysis). A 21 Gy dose was prescribed on the 90% isodose line in the tumour bed with the energy of 6 to 12 MeV (Mobetron®-IntraOp Medical).

Results

Thirty-seven ipsilateral tumour relapses occurred. Sixteen of those were in the same breast quadrant. Sixty patients died, and among those, 12 deaths were due to breast cancer. With 71.9 months of median follow-up, the 5-year Kaplan–Meier estimate of local recurrence was 2.7%.

Conclusions

The rate of breast cancer local recurrence after IOERT is low and comparable to published results for IORT and APBI. IOERT is highly operator-dependent, and appropriate applicator sizing according to tumour size is critical. When used in a selected patient population, IOERT achieves a good balance between tumour control and late radiotherapy-mediated toxicity morbidity and mortality thanks to insignificant irradiation of organs at risk.

Accelerated partial breast irradiation in early stage breast cancer

Accelerated partial breast irradiation (APBI) is increasingly used to treat select patients with early stage breast cancer. However, radiation technique, dose and fractionation as well as eligibility criteria differ between studies. This has led to controversy surrounding appropriate patients for APBI and an assessment of the toxicity and cosmetic outcomes of APBI as compared to whole breast irradiation (WBI). This paper reviews existing data for APBI, APBI delivery at our institution, and ongoing research to better define patient selection, treatment delivery, dosimetric considerations and toxicity outcomes.

Partial breast irradiation: An updated consensus statement from the American brachytherapy society

PURPOSE

In recent years, results with mature follow-up have been reported for several Phase III trials randomizing women to receive whole breast irradiation (WBI) versus varying modalities of partial breast irradiation (PBI). It is important to recognize that these methods vary in terms of volume of breast tissue treated, dose per fraction, and duration of therapy. As such, clinical and technical guidelines may vary among the various PBI techniques.

METHODS

Members of the American Brachytherapy Society with expertise in PBI performed an extensive literature review focusing on the highest quality data available for the numerous PBI options offered in the modern era. Data were evaluated for strength of evidence and published outcomes were assessed.

RESULTS

The majority of women enrolled on randomized trials of WBI versus PBI have been age >45 years with tumor size <3 cm, negative margins, and negative lymph nodes. The panel also concluded that PBI can be offered to selected women with estrogen receptor negative and/or Her2 amplified breast cancer, as well as ductal carcinoma in situ, and should generally be avoided in women with extensive lymphovascular space invasion.

CONCLUSIONS

This updated guideline summarizes published clinical trials of PBI methods. The panel also highlights the role of PBI for women facing special circumstances, such as history of cosmetic breast augmentation or prior breast irradiation, and discusses promising novel modalities that are currently under study, such as ultrashort and preoperative PBI. Updated consensus guidelines are also provided to inform patient selection for PBI and to characterize the strength of evidence to support varying PBI modalities.

Automating implant reconstruction in interstitial brachytherapy of the breast: A hybrid approach combining electromagnetic tracking and image segmentation

BACKGROUND AND PURPOSE

To develop a method for automatic reconstruction of catheter implants in interstitial brachytherapy (iBT) of the breast by means of electromagnetic tracking (EMT) with the goal of making treatment planning as time-effective and accurate as possible.

MATERIALS AND METHODS

The implant geometry of 64 patients was recorded using an afterloader prototype with EMT functionality immediately after the planning CT. EMT data were transferred to the CT image space by rigidly registering the catheter fixation buttons as landmarks. To further improve reconstruction accuracy, the EMT reconstruction points were used as starting points to define small regions of interest (ROI) in the CT image. Within these ROIs, the catheter track was segmented in the CT using image processing operations such as thresholding and blob detection, thus refining the reconstruction. The perpendicular distance between the refined EMT implant reconstruction points and the manually reconstructed catheters by an experienced treatment planner was calculated as a measure of their geometric agreement.

RESULTS

Geometrically, the refined EMT based implant reconstruction shows excellent agreement with the manual reconstruction. The median distance across all patients is 0.25 mm and the 95th percentile is 1 mm. Refinement takes approximately 0.5 s per reconstruction point and typically does not exceed 3 min per implant at no user interaction.

CONCLUSION

The refined EMT based implant reconstruction proved to be extremely accurate and fast compared to manual reconstruction. The presented procedure can in principle be easily transferred to clinical routine and therefore has enormous potential to provide significant time savings in iBT treatment planning whilst improving reconstruction accuracy.

External Beam Accelerated Partial Breast Irradiation in Early Breast Cancer and the Risk for Radiogenic Pneumonitis

In order to evaluate the risk for radiation-associated symptomatic pneumonitis in a prospective external beam accelerated partial breast irradiation (APBI) trial, between 2011 and 2021, 170 patients with early stage breast cancer were enclosed in the trial. Patients were eligible for study participation if they had a histologically confirmed breast cancer or an exclusive ductal carcinoma in situ (DCIS), a tumor size ≤3 cm, free safety margins ≥2 mm, no involved axillary lymph nodes, tumor bed clips, and were ≥50 years old. Patients received APBI with 38 Gy with 10 fractions in 10 consecutive working days. The trial was registered at the German Clinical Trials Registry, DRKS-ID: DRKS00004417. Median follow-up was 56 (1−129) months. Ipsilateral lung MLD, V20, and V30 were 4.3 ± 1.4 Gy, 3.0 ± 2.0%, and 1.0 ± 1.0%, respectively. Radiogenic pneumonitis grade 2 appeared in 1/170 (0.6%) patients two months after radiotherapy. Ipsilateral MLD, V20, and V30 were 6.1 Gy, 7, and 3% in this patient. Additionally, individual radiosensitivity was increased in this specific patient. Compared to WBI, APBI leads to lower lung doses. Using APBI, the risk of symptomatic radiogenic pneumonitis is very low and may be limited, with an ipsilateral V20 < 3% to very exceptional cases associated with innate risk factors with an increased radiation susceptibility.

CyberKnife versus multicatheter interstitial brachytherapy for accelerated partial breast irradiation: a dosimetrical assessment with focus on organs at risk

Background

The purpose of the study was to dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and stereotactic radiotherapy with CyberKnife (CK) for accelerated partial breast irradiation with special focus on dose to organs at risk (OARs).

Materials and methods

Treatment plans of thirty-one patients treated with MIBT were selected and additional CK plans were created on the same CT images. The OARs included ipsilateral non-target and contralateral breast, ipsilateral and contralateral lung, skin, ribs, and heart for left sided cases. The fractionation was identical (4 × 6.25 Gy). Dose-volume parameters were calculated for both techniques and compared.

Results

The D90 of the PTV for MIBT and CK were similar (102.4% vs. 103.6%, p = 0.0654), but in COIN the MIBT achieved lower value (0.75 vs. 0.91, p < 0.001). Regarding the V100 parameter of non-target breast CK performed slightly better than MIBT (V100: 1.1% vs. 1.6%), but for V90, V50 and V25 MIBT resulted in less dose. Every examined parameter of ipsilateral lung, skin, ribs and contralateral lung was significantly smaller for MIBT than for CK. Protection of the heart was slightly better with MIBT, but only the difference of D2cm³ was statistically significant (17.3% vs. 20.4%, p = 0.0311). There were no significant differences among the dose-volume parameters of the contralateral breast.

Conclusion

The target volume can be properly irradiated by both techniques with high conformity and similar dose to the OARs. MIBT provides more advantageous plans than CK, except for dose conformity and the dosimetry of the heart and contralateral breast. More studies are needed to analyze whether these dosimetrical findings have clinical significance.

Four-fraction ultra-accelerated minimal breast irradiation in early breast cancer: The initial feasibility results of an institutional experience

PURPOSE

To evaluate the feasibility, early toxicity, and clinical outcomes of early-breast cancer patients in a single-arm, phase I/II study of an ultra-accelerated, four-fraction schedule of minimal breast irradiation (4f-AMBI) using a multicatheter, minimally-invasive, intraoperative tumor bed implant (MITBI) during breast-conserving surgery (BCS).

METHODS AND MATERIALS

Eligible women aged >40 years with clinically and radiologically confirmed, unifocal invasive or in situ ≤3 cm tumors were considered as potential candidates for MITBI during BCS. After the pathology report, patients who met APBI criteria received ultra-accelerated four-fractions irradiation (6.2 Gy BID x 4fx over 2 days) with perioperative HDR-brachytherapy (PHDRBT). Early complications, toxicity, clinical outcomes, and cosmetic results were analyzed.

RESULTS

Of 89 patients initially implanted, 60(67.4%) were definitively included in the 4f-AMBI-protocol. The median age was 64.4 years; the median CTV was 32.1 cc (6.9-75.4 cc), and the external-V₁₀₀ was 43.1 cc (12.87-107 cc), representing 5% of the breast tissue irradiated with a median CTV D₉₀ of 6.2 Gy (5.6-6.28 Gy). The entire local treatment (BCS&MITBI-4f-AMBI) was completed at a median of 8 days (4-10 days). The rate of early complications was 11%. There were no major complications. Acute skin-subcutaneous G1 toxicity was reported in 11.7%, and late G1 toxicity on 36.7%. After a median follow-up of 27 months (11-51 months), the local, elsewhere, locoregional and distant-control rates were 100%, 98.3%, 100%, and 100% respectively. The early-cosmetic evaluation was excellent-good in 94.5% of patients evaluated.

CONCLUSIONS

Ultra-accelerated, four-fraction, minimal breast irradiation (4f-AMBI) using a minimally-invasive tumor bed implant procedure is safe, dosimetrically feasible, and shows small irradiated volumes. This program provides low toxicity rates and excellent short-term clinical and cosmesis outcomes.

First clinical experience with a novel, mobile cone-beam CT system for treatment quality assurance in brachytherapy

Background and purpose

On-site cone-beam computed tomography (CBCT) has gained in importance in adaptive brachytherapy during recent years. Besides treatment planning, there is increased need particularly for image-guidance during interventional procedures and for image-guided treatment quality assurance (QA). For this purpose, an innovative CBCT device was rolled out at our hospital as the first site worldwide. We present the first clinical images and experiences.

Materials and methods

The novel CBCT system is constructed of a 121 cm diameter ring gantry, and features a 43.2 × 43.2 cm² flat-panel detector, wireless remote-control via tablet-PC, and battery-powered maneuverability. Within the first months of clinical operation, we performed CBCT-based treatment QA for a total of 26 patients (8 with breast, 16 with cervix, and 2 with vaginal cancer). CBCT scans were analyzed regarding potential movements of implanted applicators in-situ during the brachytherapy course.

Results

With the presented device, treatment QA was feasible for the majority of patients. The CBCT scans of breast patients showed sufficient contrast between implanted catheters and tissue. For gynecologic patients, a distinct visualization of applicators was achieved in general. However, reasonable differentiations of organic soft tissues were not feasible.

Conclusion

The CBCT system allowed basic treatment QA measures for breast and gynecologic patients. For image-guidance during interventional brachytherapy procedures, the current image quality is not adequate. Substantial performance enhancements are required for intraoperative image-guidance.

Hypofractionated proton therapy in breast cancer: where are we? A critical review of the literature

PURPOSE

To critically review available literature on hypofractionated (≥ 3 Gy/fraction) proton therapy (PT) for breast cancer (BCa).

METHODS

A systematic screening of the literature was performed in April 2021 in compliance with the preferred reporting items for systematic reviews and meta-analyses recommendations. All full-text publication written in English were considered eligible. Acute and late toxicities, oncological outcomes and dosimetric features were considered for the analysis.

RESULTS

Twelve publications met the inclusion criteria; all studies but one focused on accelerated partial breast irradiation (APBI). Eleven works considered post-operative patients, one referred to ABPI as a curative-intent modality. The dosimetric profile of PT compared favorably with both photon-based 3D conformal and intensity-modulated techniques, while a more extended follow-up is warranted to fully assess both the long-term toxicities and the non-inferiority of oncological outcomes.

CONCLUSION

Our work shows that results on PT for BCa are currently only available for APBI applications, with dosimetric analyses demonstrating a clear advantage over both 3D conformal and intensity modulated X-rays techniques, especially when ≥ 2 treatment fields were used. However, further evidence is needed to define whether such theoretical benefit translates into clinical improvements, especially in the long-term.

Delivery of Adjuvant Radiation in 5 Days or Less After Lumpectomy for Breast Cancer: A Systematic Review

BACKGROUND

Recent data have been published supporting the application of ultra-short radiation therapy (RT) regimens for women with early stage breast cancer following breast conserving surgery (BCS). What has remained controversial is whether and how to apply accelerated whole breast irradiation (AWBI) or accelerated partial breast irradiation (APBI) approaches in these patients, as well as the consideration of intraoperative RT (IORT) for this population.

METHODS

We performed a systematic review of the literature searching for randomized and prospective data published evaluating ultra-short RT delivered in 5-days or less with APBI, AWBI, or IORT.

RESULTS

We identified two randomized studies applying AWBI (n=5,011 patients) with 5 to 10 year follow up, which supported the use of ultra-short course AWBI (5 fractions in one week) as compared to hypofractionated WBI. We identified six randomized trials evaluating APBI (as compared to WBI) in 5 days or less (n= 8,415) with numerous (n=55) prospective studies as well, with the data supporting short course APBI as compared to WBI. Finally, we identified two randomized trials evaluating IORT; however, both trials demonstrated elevated rates of recurrence with IORT as compared to WBI.

CONCLUSIONS

The current body of data available for ultra-short adjuvant RT regimens delivered in 5-days or less after BCS overwhelming support their utilization. While data for both exists, APBI regimens have, by far, greater numbers of patients and longer follow-up as compared to AWBI. Also, given increased rates of recurrence seen with IORT with long-term follow-up, this should not be considered a standard approach at this time.

Partial breast irradiation versus whole breast radiotherapy for early breast cancer

BACKGROUND

Breast-conserving therapy for women with breast cancer consists of local excision of the tumour (achieving clear margins) followed by radiotherapy (RT). Most true recurrences occur in the same quadrant as the original tumour. Whole breast radiotherapy (WBRT) may not protect against the development of a new primary cancer developing in other quadrants of the breast. In this Cochrane Review, we investigated the delivery of radiation to a limited volume of the breast around the tumour bed (partial breast irradiation (PBI)) sometimes with a shortened treatment duration (accelerated partial breast irradiation (APBI)).

OBJECTIVES

To determine whether PBI/APBI is equivalent to or better than conventional or hypofractionated WBRT after breast-conserving therapy for early-stage breast cancer.

SEARCH METHODS

On 27 August 2020, we searched the Cochrane Breast Cancer Group Specialised Register, CENTRAL, MEDLINE, Embase, CINAHL and three trial databases. We searched for grey literature: OpenGrey (September 2020), reference lists of articles, conference proceedings and published abstracts, and applied no language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) without confounding, that evaluated conservative surgery plus PBI/APBI versus conservative surgery plus WBRT. Published and unpublished trials were eligible.

DATA COLLECTION AND ANALYSIS

Two review authors (BH and ML) performed data extraction, used Cochrane's risk of bias tool and resolved any disagreements through discussion, and assessed the certainty of the evidence for main outcomes using GRADE. Main outcomes were local recurrence-free survival, cosmesis, overall survival, toxicity (subcutaneous fibrosis), cause-specific survival, distant metastasis-free survival and subsequent mastectomy. We entered data into Review Manager 5 for analysis.

MAIN RESULTS

We included nine RCTs that enrolled 15,187 women who had invasive breast cancer or ductal carcinoma in-situ (6.3%) with T1-2N0-1M0 Grade I or II unifocal tumours (less than 2 cm or 3 cm or less) treated with breast-conserving therapy with negative margins. This is the second update of the review and includes two new studies and 4432 more participants. Local recurrence-free survival is probably slightly reduced (by 3/1000, 95% CI 6 fewer to 0 fewer) with the use of PBI/APBI compared to WBRT (hazard ratio (HR) 1.21, 95% confidence interval (CI) 1.03 to 1.42; 8 studies, 13,168 participants; moderate-certainty evidence). Cosmesis (physician/nurse-reported) is probably worse (by 63/1000, 95% CI 35 more to 92 more) with the use of PBI/APBI (odds ratio (OR) 1.57, 95% CI 1.31 to 1.87; 6 studies, 3652 participants; moderate-certainty evidence). Overall survival is similar (0/1000 fewer, 95% CI 6 fewer to 6 more) with PBI/APBI and WBRT (HR 0.99, 95% CI 0.88 to 1.12; 8 studies, 13,175 participants; high-certainty evidence). Late radiation toxicity (subcutaneous fibrosis) is probably increased (by 14/1000 more, 95% CI 102 more to 188 more) with PBI/APBI (OR 5.07, 95% CI 3.81 to 6.74; 2 studies, 3011 participants; moderate-certainty evidence). The use of PBI/APBI probably makes little difference (1/1000 less, 95% CI 6 fewer to 3 more) to cause-specific survival (HR 1.06, 95% CI 0.83 to 1.36; 7 studies, 9865 participants; moderate-certainty evidence). We found the use of PBI/APBI compared with WBRT probably makes little or no difference (1/1000 fewer (95% CI 4 fewer to 6 more)) to distant metastasis-free survival (HR 0.95, 95% CI 0.80 to 1.13; 7 studies, 11,033 participants; moderate-certainty evidence). We found the use of PBI/APBI in comparison with WBRT makes little or no difference (2/1000 fewer, 95% CI 20 fewer to 20 more) to mastectomy rates (OR 0.98, 95% CI 0.78 to 1.23; 3 studies, 3740 participants, high-certainty evidence).

AUTHORS' CONCLUSIONS

It appeared that local recurrence-free survival is probably worse with PBI/APBI; however, the difference was small and nearly all women remain free of local recurrence. Overall survival is similar with PBI/APBI and WBRT, and we found little to no difference in other oncological outcomes. Some late effects (subcutaneous fibrosis) may be worse with PBI/APBI and its use is probably associated with worse cosmetic outcomes. The limitations of the data currently available mean that we cannot make definitive conclusions about the efficacy and safety or ways to deliver PBI/APBI. We await completion of ongoing trials.

Comparison between Accelerated Partial Breast Irradiation with multicatheter interstitial brachytherapy and Whole Breast Irradiation, in clinical practice

Purpose

The aim of this study was to compare accelerated partial breast irradiation (APBI) with multicatheter interstitial brachytherapy (BT) and whole breast irradiation (WBI), in terms of toxicity, aesthetic result, quality of life and survival, in clinical practice.

Materials and methods

A comparative study of two prospectively recorded cohorts of 76 breast cancer patients who complied with the recommendations of GEC-ESTRO for APBI was conducted. The main objective was toxicity, quality of life measured through validated questionnaires and the aesthetic results. Secondary objectives were overall survival and disease-free survival.

Results

Seventy-six stage I/II breast cancer patients, with a mean age of 66 years entered the study. APBI group showed less acute G1-2 dermatitis (51.4 vs 94.9%, p < 0.001) and late hyperpigmentation (0 vs 17.9%, p = 0.04). There were no differences in aesthetic results, both assessed by the patient herself and by the doctor. Statistically significant differences in measures of quality of life were observed in favour of the APBI, both in EORTC QLQ-BR23 and body image scale questionnaires. With a median follow-up of 72 months (6 years), the estimated overall survival at 5 and 10 years was 96.8 and 77.7%, respectively, and disease-free survival at 5 and 10 years was 91.1 and 69.4%, respectively, without statistically significant differences between groups.

Discussion

APBI is an attractive alternative in candidate patients with initial breast cancer, with benefits in acute toxicity and quality of life and fewer visits to the hospital, without compromising tumor control or survival.

Interstitial multi-catheter breast brachytherapy: Technical aspects and experience feedback in a comprehensive cancer center

PURPOSE

To focus on technical aspects of the implementation of interstitial high dose rate brachytherapy, with a step-by-step approach.

MATERIALS AND METHODS

Patients were selected during multidisciplinary tumor boards, according to inclusion criteria adapted from GEC-ESTRO guidelines. A CT scan was performed a few days before implantation. On pre-implant CT, using surgical scar and clips, surgical and pathological reports, and preoperative images, we delineated the tumor bed to be included in the Clinical Target Volume (CTV), according to GEC ESTRO Recommendations. A 3D virtual implant simulation of the best catheter positions was performed in order to cover the target volume. Implantation was then carried out under local anaesthetic using 3D projections of the catheter inlets and outlets. Dosimetry was performed on post-implantation CT scan. A dose of 34Gy was delivered in 10 fractions. Acute and late side effects, and local control were evaluated 2 and 8 months after treatment.

RESULTS

Between July 2017 and January 2020, 20 patients were treated with accelerated partial breast irradiation. Dose constraints regarding target volume coverage, overdose, dose homogeneity, conformation index and organs at risk were met in 94.7%, 100%, 63.2%, 0% and 89.5% of the treatment plans, respectively. Grade 1-2 acute adverse events were observed in 21% of patients, with no grade 3-4 events.

CONCLUSION

The first dosimetric results and early clinical tolerance and efficacy achieved by the implementation of breast interstitial multicatheter brachytherapy in routine clinical practice are very encouraging, and confirm the interest of extending this practice.

Multicatheter interstitial brachytherapy versus stereotactic radiotherapy with CyberKnife for accelerated partial breast irradiation: a comparative treatment planning study with respect to dosimetry of organs at risk

Background

The aim of the study was to dosimetrically compare multicatheter interstitial brachytherapy (MIBT) and stereotactic radiotherapy with CyberKnife (CK) for accelerated partial breast irradiation (APBI) especially concerning the dose of organs at risk (OAR-s).

Patients and methods

Treatment plans of thirty-two MIBT and CK patients were compared. The OAR-s included ipsilateral non-target and contralateral breast, ipsilateral and contralateral lung, skin, ribs, and heart for left-sided cases. The fractionation was identical (4 x 6.25 Gy) in both treatment groups. The relative volumes (e.g. V100, V90) receiving a given relative dose (100%, 90%), and the relative doses (e.g. D0.1cm³, D1cm³) delivered to the most exposed small volumes (0.1 cm³, 1 cm³) were calculated from dose-volume histograms. All dose values were related to the prescribed dose (25 Gy).

Results

Regarding non-target breast CK performed slightly better than MIBT (V100: 0.7% vs. 1.6%, V50: 10.5% vs. 12.9%). The mean dose of the ipsilateral lung was the same for both techniques (4.9%), but doses irradiated to volume of 1 cm³ were lower with MIBT (36.1% vs. 45.4%). Protection of skin and rib was better with MIBT. There were no significant differences between the dose-volume parameters of the heart, but with MIBT, slightly larger volumes were irradiated by 5% dose (V5: 29.9% vs. 21.2%). Contralateral breast and lung received a somewhat higher dose with MIBT (D1cm³: 2.6% vs. 1.8% and 3.6% vs. 2.5%).

Conclusions

The target volume can be properly irradiated by both techniques with similar dose distributions and high dose conformity. Regarding the dose to the non-target breast, heart, and contralateral organs the CK was superior, but the nearby organs (skin, ribs, ipsilateral lung) received less dose with MIBT. The observed dosimetric differences were small but significant in a few parameters at the examined patient number. More studies are needed to explore whether these dosimetric findings have clinical significance.

Long-Term Outcomes of Once-Daily Accelerated Partial-Breast Irradiation With Tomotherapy: Results of a Phase 2 Trial

PURPOSE

We report long-term outcomes of phase 2 trial on patients with invasive breast cancer treated with accelerated partial-breast irradiation (APBI) using tomotherapy after breast conservative surgery.

METHODS AND MATERIALS

From December 2010 to December 2018, we treated 338 women with APBI-tomotherapy: 38.5 Gy in 10 once-daily fractions. Patients selected were age ≥50 years old, with ≤3 cm in size unifocal tumor and at least 2 mm of clear margins. Disease outcomes were analyzed by clinicopathologic characteristics, molecular phenotypes, and American Society for Radiation Oncology (ASTRO) 2017 updated consensus groupings.

RESULTS

The median age was 65 years (range, 50-86). The invasive ductal (87.5%) and the luminal A-like molecular phenotype (70%) were the most common tumors. Overall 242 patients (71.6%) were considered "suitable" for enrollment in APBI according to the eligibility criteria of the ASTRO-2017 consensus statement. With a median follow-up of 76 months (range, 17-113), 2 patients (0.6%) had an invasive ipsilateral breast tumor recurrence (IBTR), and 2 patients (0.6%) had an axillary ipsilateral failure. The rate of local control in terms of free of IBTR was 99.4% and locoregional control (no recurrence in ipsilateral breast as well as in regional nodes) was 98.8%. Progression-free survival was 98.4% and 92% at 5 and 10 years, respectively. Acute and late skin toxicity, graded according to the Common Terminology Criteria for Adverse Events, were 7.7% (G1) and 0.6% (G2) and 4.4% (G1) and 1.1% (G2), respectively. There were no grade 3/4 toxicities, however. Very few patients (2%) or physicians (2%) assessed cosmetic outcome as fair or poor at the 2-year follow-up.

CONCLUSIONS

This phase 2 trial on APBI-tomotherapy shows excellent long-term results. Once-daily fractionation schedule was well tolerated with a low rate of adverse events and worse cosmetic outcome. In this series, even among those deemed cautionary or unsuitable for APBI by ASTRO criteria, we demonstrated a low rate of IBTR.

The Case for Brachytherapy: Why It Deserves a Renaissance

The recent global events related to the coronavirus disease of 2019 pandemic have significantly changed the medical landscape and led to a shift in oncologic treatment perspectives. There is a renewed focus on preserving treatment outcomes while maintaining medical accessibility and decreasing medical resource utilization. Brachytherapy, which is a vital part of the treatment course of many cancers (particularly prostate and gynecologic cancers), has the ability to deliver hypofractionated radiation and thus shorten treatment time. Studies in the early 2000s demonstrated a decline in brachytherapy usage despite data showing equivalent or even superior treatment outcomes for brachytherapy in disease sites, such as the prostate and cervix. However, newer data suggest that this trend may be reversing. The renewed call for shorter radiation courses based on data showing equivalent outcomes will likely establish hypofractionated radiation as the standard of care across multiple disease sites. With shifting reimbursement, brachytherapy represents the pinnacle in hypofractionated, conformal radiation therapy, and with extensive long-term data in support of the treatment modality brachytherapy is primed for a renaissance.

A meta-analysis of the efficacy and safety of accelerated partial breast irradiation versus whole-breast irradiation for early-stage breast cancer

OBJECTIVE

This meta-analysis evaluated the efficacy and safety of accelerated partial breast irradiation versus whole-breast irradiation for early-stage breast cancer after breast-conserving surgery.

MATERIALS AND METHODS

A systematic search of PubMed, Embase, and the Cochrane libraries was performed according to the PRISMA statement the last 10 years to April 7, 2020 to identify the randomized controlled trials of APBI versus WBI for treating patients with early-stage breast cancer. Two independent observers evaluated the identified studies. The obtained data were analyzed using the RevMan 5.3 software.

RESULTS

A total of 10 randomized controlled trials involving 15,500 patients with early-stage breast cancer were selected according to the inclusion and exclusion criteria and included in this meta-analysis. In this meta-analysis, we included ten studies that reported local recurrence and found significant differences in local recurrence rates (HR = 1.46; 95% CI 1.20-1.79, P = 0.0002). Further analysis showed that this difference may be related to the choice of treatment methods. No differences in distant metastasis, breast cancer deaths, contralateral breast cancer, disease-free survival, and overall survival rates were observed between WBI and APBI groups. There was no significant difference in late toxicity, cosmetic outcomes and quality of life between the two groups, the compliance and tolerance of the patients were well. Compared to whole breast irradiation, accelerated partial breast irradiation significantly reduced serious (≥ grade 2) early toxicities, especially regarding acute skin toxicity.

CONCLUSIONS

The analysis showed that patients receiving APBI had a higher local recurrence rate, but no differences in distant metastasis, breast cancer deaths, contralateral breast cancer, disease-free survival, and overall survival rates.

Breast brachytherapy

Accelerated partial breast irradiation with brachytherapy is a treatment method with a very low risk profile. In fact, accelerated partial breast irradiation brachytherapy has been proven in randomized trials to have fewer late side effects than whole-breast irradiation. Notably, Grade 3 late side effects are extremely rare, and excellent to good cosmetic results are observed in well over 90% of patients. In this article, published side effects of breast brachytherapy are reviewed and appropriate management discussed.

Management of ductal carcinoma in situ with accelerated partial breast irradiation brachytherapy: Implications for guideline expansion

PURPOSE

Accelerated partial breast irradiation (APBI) for patients with ductal carcinoma in situ (DCIS) is controversial, and the suitability criteria from the American Brachytherapy Society (ABS), American Society of Therapeutic Radiology and Oncology (ASTRO), and the European Society for Radiotherapy and Oncology (GEC-ESTRO) have important differences.

METHODS AND MATERIALS

This is a single-institution retrospective review of 169 consecutive patients with DCIS who underwent lumpectomy followed by APBI intracavitary brachytherapy from 2003 to 2018. Outcomes, including overall survival, recurrence-free survival (RFS), ipsilateral breast tumor recurrence, and distant metastasis, were estimated with the Kaplan-Meier method.

RESULTS

The median followup time was 62.5 months. Median age was 66 years (47-89 years). The majority of patients had estrogen receptor-positive disease (89%). Fifty patients (30%) had Grade 3 disease. Of the 142 patients with adequate pathology interpretation, 91 and 108 cases had margins ≥ 3 mm and ≥2 mm, respectively. Most patients (72%) were prescribed and started endocrine therapy. Of the patients evaluable for ABS criteria (N = 130), 97 met the suitability criteria. Of the patients evaluable for ASTRO criteria (N = 129), 42 were deemed cautionary and 33 were deemed unsuitable. Of the patients evaluable for GEC-ESTRO criteria (N = 143), 141 cases were at intermediate risk and two were at high risk. Five-year ipsilateral breast tumor recurrence, RFS, and overall survival were 0.6%, 97.7%, and 97.2%, respectively. The ABS, ASTRO, and GEC-ESTRO criteria failed to significantly predict for RFS.

CONCLUSIONS

These results, although limited by short-term followup, indicate that expansion of the eligibility criteria of APBI for patients with DCIS should be considered.

Very accelerated partial breast irradiation Phase I-II multicenter trial (VAPBI): Feasibility and early results

PURPOSE

This is a multicenter Phase I-II trial endorsed by the GEC-ESTRO Breast Working Group, to analyze if very accelerated partial breast irradiation (VAPBI) with multicatheter interstitial brachytherapy is feasible and safe compared with the standard APBI treatment in 4-5 days for early stage breast carcinomas.

METHODS AND MATERIALS

We have included 81 patients with pT1-2 pN0 invasive carcinomas after breast-conserving surgery. Between August 2017 and July 2019, 33 women received high-dose-rate brachytherapy, four fractions of 6.25 Gy in 2-3 days, and 48 patients received three fractions of 7.45 Gy in 2 days. Thirty-six patients were implanted perioperatively and 45 postoperatively. Mean age was 68 (51-90). Free surgical margins were of 2 mm or greater.

RESULTS

Acute effects were 11% dermatitis, 18.5% hematoma, 3.7% infection, and 14.8% pain. At a median followup of 20 months (range 8-35), no relapse has occurred. Pigmentation changes in the entrance and exit of tubes were visible in 16%, but 1 year later, few cases remained. Patients developed G1-2 induration or fibrosis in 18.5% and 2.5%, respectively. No patient developed telangiectasia. The cosmetic outcome was good/excellent in 97.5% and fair in 2.5%.

CONCLUSIONS

VAPBI with multicatheter interstitial brachytherapy using four fractions of 6.25 Gy or three fractions of 7.45 Gy in two or 3 days is feasible. No excess has been observed in acute effects. At a mean followup of 20 months, late side effects seem to be similar to standard fractionation. VAPBI in two to 3 days is beneficial for the patients and reduces the workload of the brachytherapy units.

Is it important to define skin sub-volumes in breast brachytherapy?

Aim:

To evaluate clinically pertinent skin dose and volume parameters for the development of toxicities following accelerated partial breast irradiation (APBI).

Methods:

Three skin structures of various thicknesses inside the body (2 mm, 3 mm, 4 mm) were contoured over the treated breast retrospectively in a cohort of 62 women who underwent APBI using multi-catheter interstitial brachytherapy. The correlation statistics between the various skin structures and acute and late skin sequelae were evaluated using the Mann–Whitney U test and receiver-operating characteristic analysis. A p-value of <0·05 was considered significant.

Results:

At a median follow-up period of 54 months (range: 28–86), a significant correlation was seen between dose received by 0·2 (D0·2) cc of skin 4 mm inside the body as well as volume receiving 100% dose (V100) of skin 3 mm inside the body with cosmesis at 2 years and at last follow-up. The threshold for the two parameters for prediction of excellent or good cosmesis was 90% of the prescribed dose and 0·05 cc, respectively. No significant dosimetric or volumetric correlation was seen with other sequelae like wound dehiscence, fat necrosis, telangiectasia and atrophy.

Conclusion:

The results of this study support the use of dose and volumetric indices of the sub-volumes of the skin for correlation with clinical endpoints. However, the same should be validated prospectively in a larger cohort of women undergoing breast brachytherapy.

A reliable skin toxicity predictor in permanent breast seed implant brachytherapy

PURPOSE

To establish skin dose-outcome relationships using a reliable metric in permanent breast seed implant (PBSI).

METHODS

Sixty-seven consecutive patients who underwent PBSI at our institution were included. Skin doses were calculated using two skin dose indices: maximum point dose to the skin surface, D_max, and D_0.2cc for a 2-mm internal skin rind (a surrogate to the dose to 1 cm² area of skin) from CT-based postoperative treatment plans. Toxicity data were extracted from patients' charts and photographs. The associations between skin dose and skin toxicity were investigated using the analysis of variance, and the predictive performance of skin dose measures was evaluated using receiver operating characteristic curves.

RESULTS

For acute reactions, 49.3% of patients had Grade 1, 4.5% Grade 2, and 1.5% Grade 3 toxicity. For telangiectasia at 3 years, very minor and minimally apparent telangiectasia was observed in 25% of patients. Moderate but asymptomatic telangiectasia was observed in 9.1% of cases. Both metrics were significantly associated with the occurrence of acute toxicity and telangiectasia at 3 years (p < 0.01). The predictive values for D_max and D_0.2cc were 0.779 and 0.763, respectively, (p < 0.0001) for acute skin toxicity and 0.786 and 0.810 for telangiectasia (p < 0.0002). Extreme dose outliers (up to 878 Gy) and a high variability were observed for D_max but not for D_0.2cc, illustrating the superior reliability of D_0.2cc.

CONCLUSION

D_0.2cc, as an alternate skin dose measure to D_max, is a robust metric for measuring skin dose that is simple to calculate, yet is clinically relevant and not prone to inaccuracies inherent to point dose measurement.

Treating Positive Axillary Disease in Elderly Breast Cancer Patients: The Impact of Age on Radiation Therapy

Introduction

Breast cancer is the second most common cause of cancer death in females, and 30% of these patients are over the age of 70 years. Studies have shown deviation from the standard treatment paradigms in the elderly, especially in regard to radiation treatment.

Methods

We performed a retrospective chart review on 118 patients over the age of 70 years diagnosed with breast cancer and pathologically proven axillary disease over an 8-year period at an urban academic hospital to examine which patient factors influenced radiotherapy.

Results

Increasing patient age was associated with a decrease in the probability of receiving radiotherapy, while HER2-negative patients were more likely to receive radiation. Neither race, number of coexisting medical conditions, or insurance status showed any influence on radiation treatment.

Conclusion

Patient age has a significant influence if elderly patients with axillary disease receive radiotherapy. Further investigation and validation are needed to understand why chronological age rather than biological age influences treatment modalities.

Modern development of high-dose-rate brachytherapy

Brachytherapy is an invasive therapy with placement of radiation source into or near the tumor. The difference between planning target volume and clinical target volume is minimal, and the dose out of the tumor reduces rapidly due to the inverse-square law. High-dose-rate brachytherapy enables three-dimensional image guidance, and currently, tumor dose as well as doses of the surrounding normal structures can be evaluated accurately. High-dose-rate brachytherapy is the utmost precision radiation therapy even surpassing carbon ion therapy. Biological disadvantages of high-dose rate have been overcome by the fractional irradiation. High-dose-rate brachytherapy is indispensable in the definitive radiation therapy of cervical cancer. Also in prostate cancer and breast cancer, high-dose-rate brachytherapy plays a significant role. Brachytherapy requires techniques and skills of radiation oncologists at the time of invasive placement of the radiation source into the tumor area. Education of young radiation oncologists is most urgent and important.

Radiochromic film in vivo dosimetry predicts early the risk of acute skin toxicity for brachytherapy partial breast irradiation

Brachytherapy accelerated partial breast irradiation (APBI) is well tolerated, but reported acute toxicities including moist desquamation rates range from 7% to 39%. Moist desquamation is correlated to long-term skin toxicity and high skin dose is the main risk factor. This study uses radiochromic films for in vivo skin dosimetry of low dose rate (LDR) APBI brachytherapy and prediction of skin toxicity. Patients participating in a clinical trial assessing skin toxicity of LDR seed brachytherapy were included in this study. Following the seed implantation procedure, patients were asked to wear a customized oval shaped radiochromic film on the skin projection of the planned target volume (PTV) for 24 h. Exposed films were collected, and maximum point doses were measured. In addition, maximum doses to a small skin volume (D_0.2cc) were calculated on the pre- and post-implant CT-scan. Acute skin toxicities (redness, pigmentation, induration and dermatitis) were scored by the treating physician for 2 months during follow-up visits. Skin dose measurements and acute toxicity were available for 18 consecutive patients. The post-implant calculated maximum skin doses (D_0.2cc), 60.8 Gy (SD ± 41.0), were on average 30% higher than those measured in vivo (D_max-film), 46.6 Gy (SD ± 19.3), but those values were highly significantly correlated (Spearman's rho 0.827, p < 0.001). Also, dermatitis and induration were significantly correlated with higher in vivo measured and post-implant calculated skin dose. Pre-implant dosimetry was not correlated with measured or post-implant skin dose or side effects. Radiochromic films can reliably diagnose excess dose to the skin during the first 24 h and predict skin toxicity, which enables preventative measures. Trial registration: Nederlands Trial Register (www.trialregister.nl), NTR6549, the trial was registered prospectively on 27 June 2017. ABR number: NL56210.078.16.

Accelerated Partial Breast Irradiation: A New Standard of Care?

Background

Breast-conserving therapy including lumpectomy and adjuvant whole breast irradiation (WBI) has become the standard therapy for early-stage breast cancer (EBC). Without WBI, the recurrence rate is significantly increased. However, when selecting patients at a low a priori risk of local recurrence only a small breast-cancer-specific mortality benefit, but no overall survival improvement, was detected for WBI. As most recurrences occur close to the lumpectomy cavity, accelerated partial breast irradiation (APBI) delivered exclusively to a limited volume of tissue around the initial lumpectomy site, has gained increased attention and is now discussed as an alternative to WBI for selected EBC patients.

Summary

Numerous techniques for APBI (interstitial brachytherapy, external beam-based APBI, intraoperative radiotherapy, MR-guided radiotherapy) allow treatment delivery in a shorter period of time, and radiation oncologists expect to further reduce side effects by using these new techniques, with improvements in cosmetics and quality of life. In this review, we aim to describe the existing evidence for the feasibility and effectiveness of different APBI techniques used in modern radiotherapy.

Key Messages

APBI has provided outcomes similar to WBI combined with potentially reduced toxicity. While appropriate patient selection persists to be crucial for acceptable recurrence rates, the precise definition of patients suitable for APBI remains a matter of discussion. As long-term data are often still lacking, special attention should be paid to late side effects and long-term outcomes. Decision-making on appropriate treatment techniques should take into account not only local control rates, but also the impact on the patient's quality of life.

Hypofractionated radiation therapy for invasive breast cancer: From moderate to extreme protocols

Adjuvant irradiation is the standard treatment after breast conservative surgery. Normofractionated regimen with an overall treatment time of 5 to 6 weeks is often considered as a limiting factor for irradiation compliance. In order to answer this issue, moderate and more recently extreme hypofractionated protocols appeared. We report here oncological outcomes and toxicity of hypofractionated breast irradiation. After defining the frame of moderate and extreme hypofractionated breast irradiations based on overall treatment time, patient selection criteria were listed. According to their levels of proof, the results of moderate and extreme hypofractionated breast irradiation were analysed. Overall treatment time for moderate hypofractionated breast irradiation ranged from 3 to 4 weeks, while for extreme hypofractionated breast irradiation, it was less than 1 week. For moderate hypofractionated breast irradiation, whole breast irradiation was currently performed with or without lymph node irradiation. Moderate hypofractionated breast irradiation has proven to be as safe and as efficient as normofractionated breast irradiation with level IA evidence. For extreme hypofractionated breast irradiation, phase III randomized trials confirmed that accelerated partial breast irradiation was non-inferior in terms of local control compared to normofractionated whole breast irradiation (with external beam radiation therapy and multicatheter brachytherapy), with similar acute and late toxicity. While the use of intraoperative breast irradiation remains under debate, new very accelerated partial breast irradiation (overall treatment time not exceeding 2 days) protocols emerged with encouraging results. Accelerated partial breast irradiation is warranted for extreme hypofractionated breast irradiation and is indicated for low-risk breast cancers. Moderate and extreme hypofractionated breast irradiation regimens are validated and can be routinely proposed according to patient selection criteria.

Modern Brachytherapy

Brachytherapy involves the placement of radioactive sources within or very close to the tumor. This placement allows a high dose of radiotherapy to be delivered to the tumor while sparing the surrounding normal tissue. The delivery of brachytherapy has changed markedly over the years, with newer radioactive sources making delivery safer, image guidance techniques allowing more accurate placement of sources, and advanced planning systems allowing brachytherapy to be truly adaptive. This article explores the most modern techniques and current uses of brachytherapy in the treatment of gynecological, prostate, breast, rectal, and skin cancers.

Is adaptive treatment planning in multi-catheter interstitial breast brachytherapy necessary?

PURPOSE

For 55 patients treated with interstitial multi-catheter breast brachytherapy the need for adaptive treatment planning was assessed.

METHODS AND MATERIALS

For all patients a treatment planning computed tomography (CT) and a follow-up CT were acquired and used for the retrospective evaluation. Keeping dwell time and dwell positions constant, the treatment plan assessed directly after catheter implantation was compared to the situation 48 h after implantation. Both manual catheter reconstructions, based on the planning and follow-up CT, were rigid registered to each other and the resulting deviations analyzed, like the difference between corresponding dwell positions (ΔDP) or the discrete Fréchet distance. Further, the dosimetric changes, e.g., coverage index (ΔCI), conformal index (ΔCOIN) and dose non-uniformity ratio (ΔDNR) were considered for a deformed planning target volume (PTV) and the rigid warped PTV structure. The PTV was deformed according to the vector field estimated between the two acquired CTs.

RESULTS

Over all patients with rigid aligned CTs a mean ΔDP, ΔCI, ΔCOIN and ΔDNR were determined to 2.41 ± 1.73 mm, 3.10 ± 3.17%, 0.009 ± 0.007 and 0.036 ± 0.040, respectively. Considering the deformed PTV ΔCI was estimated to 5.05 ± 4.14%.

CONCLUSION

In conclusion, in 4% of the cases re-planning would have been beneficial to ensure the planned dose delivery. Large PTV changes or large DP deviations were found to be the main reasons for dosimetric variations.

Image-guided high-dose-rate interstitial brachytherapy for recurrent rectal cancer after salvage surgery: a case report

Treatment options for patients with recurrent rectal cancer in pelvis represent a significant challenge because the balance of efficiency and toxicity needs to be pursued. This case report illustrates a treatment effect of image-guided high-dose-rate interstitial brachytherapy (HDR-ISBT) for locally relapsed rectal cancer after salvage surgery. A 61-year-old male who underwent laparoscopic high anterior resection (LAP-HAR) with D3 lymph node dissection as a primary treatment for rectal cancer (pT3N0M0, well-differentiated adenocarcinoma) had relapsed locally 8 months after initial surgery, for which he underwent salvage abdominal perineal resection (APR), followed by adjuvant 8 cycles of XELOX (capecitabine and oxaliplatin) chemotherapy. He developed pelvic recurrence 1 year after the second surgery. Image-guided HDR-ISBT was performed (30 Gy/5 fractions/3 days) followed by external beam radiation therapy with 39.6 Gy in 22 fractions. There were no severe complications related to salvage radiotherapy. CEA was decreased from 24.5 ng/ml to 0.7 ng/ml, 4 months after the salvage radiotherapy. Complete response was noted on follow-up MRIs done on 2, 5, 8, and 14 months after the treatment. Hence, HDR-ISBT appears to be effective for locally recurrent rectal cancer even after salvage surgery.