Recommendations from GEC ESTRO Breast Cancer Working Group (I): Target definition and target delineation for accelerated or boost Partial Breast Irradiation using multicatheter interstitial brachytherapy after breast conserving closed cavity surgery

Benefit of respiratory gating in the Danish Breast Cancer Group partial breast irradiation trial

BACKGROUND AND PURPOSE

Partial breast irradiation (PBI)has beenthe Danish Breast Cancer Group(DBCG) standard for selected breast cancer patients since 2016 based onearlyresults from the DBCG PBI trial.During trial accrual, respiratory-gated radiotherapy was introduced in Denmark. This study aims to investigate the effect of respiratory-gating on mean heart dose (MHD).

PATIENTS AND METHODS

From 2009 to 2016 the DBCG PBI trial included 230 patientswith left-sided breast cancer receiving external beam PBI, 40 Gy/15 fractions/3 weeks.Localization of the tumor bed on the planning CT scan, the use of respiratory-gating, coverage of the clinical target volume (CTV), and doses to organs at risk were collected.

RESULTS

Respiratory-gating was used in 123 patients (53 %). In 176 patients (77 %) the tumor bed was in the upper and in 54 patients (23 %) in the lower breast quadrants. The median MHD was 0.37 Gy (interquartile range 0.26-0.57 Gy), 0.33 Gy (0.23-0.49 Gy) for respiratory-gating, and 0.49 Gy (0.31-0.70 Gy) for free breathing, p < 0.0001. MHD was < 1 Gy in 206 patients (90 %) and < 2 Gy in 221 patients (96 %). Respiratory-gating led to significantly lower MHD for upper-located, but not for lower-located tumor beds, however, all MHD were low irrespective of respiratory-gating. Respiratory-gating did not improve CTV coverage or lower lung doses.

CONCLUSIONS

PBI ensured a low MHD for most patients. Adding respiratory-gating further reduced MHD for upper-located but not for lower-located tumor beds but did not influence target coverage or lung doses. Respiratory-gating is no longer DBCG standard for left-sided PBI.

Salvage brachytherapy for second ipsilateral breast tumor event: Relating dosimetric analysis to late side effects

PURPOSE

For second ipsilateral breast tumor event (2ndIBTE), conservative treatment (CT) involving wide local excision plus accelerated partial breast reirradiation (APBrI) is increasingly used as an alternative to mastectomy. This study investigates the impact of APBrI technique and multicatheter interstitial high dose-rate brachytherapy (MIB) dosimetry parameters on toxicity and survival in patients with 2ndIBTE.

MATERIALS-METHODS

Data from patients with 2ndIBTE treated with CT, were analyzed. Inclusion criteria specified 2ndIBTE occurring at least one year after 1st CT for primary breast cancer. Treatment details and dosimetry parameters were recorded. Primary endpoint was late toxicity. Secondary endpoints were late toxicity prognostic factors analysis and oncological outcome.

RESULTS

From 07/2005 and 07/2023, 201 patients (pts) received 2nd CT. With a median follow-up of 49.6 months (44.9-59.5), tumor size was less than 2 cm (88.1%), with estrogen receptor positive (92.7%). Patients were low (63.7%) or intermediate (29.8%) GEC-ESTRO APBI risk classification. Late toxicities were observed in 34.8% (G1 52.3%, G2 40.7%). Cutaneous fibrosis was the most common toxicity. Cosmetic outcomes were excellent in 64.1%. Dosimetry analysis revealed positive correlations between complications and absolute volumes of CTV, V100, V150, and V200. Volumes requiring higher needle number and lower DNR resulted in fewer complications. 5-year disease-free and overall survival were 88% and 95% respectively.

CONCLUSION

Second CT for 2ndIBTE showed favorable oncological outcomes and survival rates. Complications were correlated with specific dosimetric parameters, emphasizing the importance of tailored treatment planning. This study provides valuable insights in risk stratification and MIB optimization for APBrI.

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.

Ultra-hypofractionated one-week locoregional radiotherapy for patients with early breast cancer: Acute toxicity results

Purpose

Moderate hypofractionated radiotherapy is the standard of care for all patients with breast cancer, irrespective of stage or prior treatments. While extreme hypofractionation is accepted for early-stage tumours, its application in irradiating locoregional lymph nodes remains controversial.

Materials and methods

A prospective registry analysis from July 2020 to September 2023 included 276 patients with early-stage breast cancer treated with one-week ultra-hypofractionation (UHF) at 26 Gy in 5 fractions on the whole breast (58.3 %) or thoracic wall (41.7 %) and ipsilateral regional lymph nodes and simultaneous integrated boost (58.3 %). Primary endpoint was assessment of acute adverse events (AEs). Secondarily, onset of early-delayed toxicity was assessed. A minimum 6-month follow-up was required for assessing potential treatment-related early-delayed complications. Acute or late complications attributable to treatment were assessed at inclusion using the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 criteria.

Results

With a median follow-up of 19 months (range 1-49 months), 159 (57.6 %) patients reported AEs, predominantly grade (G) 1 (n = 139, 50.4 %) and G2 (n = 20, 7.8 %). Skin acute toxicity was common (G1/2: 134, G3: 14), while breast oedema occurred in 10 patients (G1: 9, G2: 1), and 15.9 % reported breast pain (G1: 42, G2: 2). Ipsilateral arm oedema was observed in 1.8 % patients. For patients with a follow-up beyond 6 months (n = 213), 23.4 % patients reported G1/G2 skin AEs, 8.8 % had G1/G2 breast/chest wall oedema, and 8.9 % experienced arm lymphedema. There were no cases of brachial plexopathy or G3 toxicity in this group of patients.

Conclusions

One-week UHF adjuvant locoregional radiation is well-tolerated, displaying low-toxicity profiles comparable to other studies using similar irradiation schedules.

Management of second ipsilateral breast tumor event: An advocacy for a randomized trial

For a second ipsilateral breast tumor event, salvage mastectomy is the standard of care while second conservative treatment is a possible option. However, level 1 proofs are missing, leading to perform salvage mastectomy for patients who could receive second conservative treatment and consequently avoid psychological/quality of life salvage mastectomy deleterious impacts. A phase 3 randomized trial comparing salvage mastectomy to second conservative treatment is needed. Here we discuss what would be to us the optimal design of such trial to confirm the non-inferiority between the two salvage options, with a focus on methodological aspects in terms of patient characteristics and statistical issues.

Investigating the impact of breast positioning control on physical treatment parameters in multi-catheter breast brachytherapy

PURPOSE

To assess the effects of a workflow for reproducible patient and breast positioning on implant stability during high-dose-rate multi-catheter breast brachytherapy.

METHODS

Thirty patients were treated with our new positioning control workflow. Implant stability was evaluated based on a comparison of planning-CTs to control-CTs acquired halfway through the treatment. To assess geometric stability, button-button distance variations as well as Euclidean dwell position deviations were evaluated. The latter were also quantified within various separated regions within the breast to investigate the location-dependency of implant alterations. Furthermore, dosimetric variations to target volume and organs at risk (ribs, skin) as well as isodose volume changes were analyzed. Results were compared to a previously treated cohort of 100 patients.

RESULTS

With the introduced workflow, the patient fraction affected by button-button distance variations > 5 mm and by dwell position deviations > 7 mm were reduced from 37% to 10% and from 30% to 6.6%, respectively. Implant stability improved the most in the lateral to medial breast regions. Only small stability enhancements were observed regarding target volume dosimetry, but the stability of organ at risk exposure became substantially higher. D0.2ccm skin dose variations > 12.4% and D0.1ccm rib dose variations > 6.7% were reduced from 11% to 0% and from 16% to 3.3% of all patients, respectively.

CONCLUSION

Breast positioning control improved geometric and dosimetric implant stability for individual patients, and thus enhanced physical plan validity in these cases.

Second Conservative Treatment for Local Recurrence Breast Cancer: A GEC-ESTRO Oncological Outcome and Prognostic Factor Analysis

PURPOSE

For second ipsilateral breast tumor event (2nd IBTE), second conservative treatment (2nd CT) combining lumpectomy plus accelerated partial breast reirradiation (APBrI) represents a curative option. The aim of this study was to analyze oncological prognostic factors for patients with a 2nd IBTE treated with 2nd CT.

METHODS AND MATERIALS

An analysis of clinical practices was conducted across 7 academic hospitals/cancer centers in 6 European countries based on the GEC-ESTRO database. Patients presenting a 2nd IBTE occurring after conservative surgery (lumpectomy + axillary evaluation) and irradiation performed for the primary tumor underwent a 2nd CT with brachytherapy-based APBrI. The main outcome was 5-year cumulative incidence (CI) rate of second local relapse. All analyzed patients were classified according to risk groups for Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) accelerated partial breast irradiation (APBI) and molecular classification and time interval between first and second breast surgery (TIS1S2). Finally, we combined GEC-ESTRO APBI, molecular, and TIS1S2 risk groups, leading to the definition of a new score (named TAM: score based on the combination of time interval [T] between first and second surgery and APBI [A] and molecular [M] classifications) specifically designed for 2nd IBTE oncological outcome analysis.

RESULTS

From July 1994 to January 2021, a total of 508 patients received a 2nd CT. At the time of 2nd IBTE, median age was 64.6 years (range, 56.2-72.6). With a median follow-up of 60.9 months (56.2-72.6), the 5-year second local relapse CI rate was 4% (95% confidence interval [95% CI], 2%-6%). The 5-year distant metastasis disease CI rate was 7% (95% CI, 4%-10%). Five-year disease-free and overall survival rates were 89% (95% CI, 86%-93%) and 91% (95% CI, 88%-94%), respectively. In multivariate analysis, TAM score was an independent prognostic factor for all the oncological items (P < .001) except disease-specific survival (P = .07) and overall survival (P = .09). The grade ≥3 late toxicity rate was 12.1%.

CONCLUSIONS

This analysis of 2nd CT combining lumpectomy with APBrI for 2nd IBTE confirmed the excellent oncological results obtained after 2nd CT. Furthermore, the GEC-ESTRO TAM score appears to be an important prognostic factor, assisting patients and physicians in the decision-making process.

Economic evaluation and budget-impact of accelerated partial breast irradiation (APBI) versus standard or hypofractionated whole breast irradiation (WBI) in postmenopausal women with early-stage breast cancer. Results from the French SHARE randomized trial

PURPOSE

This economic evaluation reports the incremental cost-utility ratio and national budget impact in France of accelerated partial breast irradiation (APBI) vs standard or hypofractionated whole breast irradiation (WBI) in breast cancer patients at low risk of local recurrence.

MATERIALS AND METHODS

We compared 490 women randomized to the APBI (ten fractions delivered twice daily over one week) with 488 women in the WBI arm (one fraction per day delivered five days per week over three or six weeks). We took the perspective of the French national health insurance with a three-year time horizon. The outcome was quality-adjusted life years (QALYs). The incremental cost-effectiveness ratio was estimated and uncertainty was explored by probabilistic bootstrapping. Transportation and sick leave costs were added in a sensitivity analysis and a national budget impact analysis based on the incidence of breast cancer estimates in France performed.

RESULTS

At three years, the average cost per patient was €2,549 (±1,954) in the APBI arm and €4,468 (±1,586) in the WBI arm (p-value < 0.001), radiotherapy was the main driver of the difference between the two arms. No significant difference was found in QALYs. For an average of 60,000 new cases of breast cancer diagnosed annually in France, 28,000 would be eligible for treatment with APBI. A 100% uptake of APBI would result in a yearly30 million€ cost saving.

CONCLUSION

APBI for the treatment of postmenopausal women with early-stage breast cancer is cost saving, with no difference in outcome measured by QALYs.

A single-institution retrospective analysis of intraoperative radiation boost during breast-conservation treatment for breast cancer

BACKGROUND

As part of a breast-conservation strategy for breast cancer, there are presently no data from randomized controlled studies on the use of intraoperative radiation (IORT) as a tumor bed boost. The effectiveness and safety of IORT as a boost therapy at a tertiary cancer center were retrospectively reviewed in this study.

METHODS

Patients had breast-conserving surgery from 2012 to 2016 that included staging of the axillary lymph nodes, a single dose of 20 Gy IORT with 50-kV photons, whole-breast irradiation (WBI), and (neo-)adjuvant systemic treatment (if applicable). During the follow-up patients were monitored for the assessment of acute and late toxicities (using the Common Terminology Criteria for Adverse Events version 4.03). Results included ipsilateral (IBTR), contralateral (CBE), and distant metastasis-free (DMFS) breast progression-free survival, as well as overall survival (OS).

RESULTS

The 68 patients had a median follow-up of 91.5 months (with a range of 9-125). Most patients (n = 51) had T1 disease and were clinically node negative. Only a small number of individuals had triple negative or high-grade illness. The majority of patients had sentinel node biopsy, and three (4.4%) had to have their tumors removed again since their original margins were positive. Finally, there were no distinct tumor bed margins. Neoadjuvant chemotherapy was administered to ten (14.7%). The median duration from BCS to WBI was 54.5 days, and conventionally fractionated WBI was used to accomplish WBI most frequently (n = 57, 96.6%). IORT was administered in a single 20 Gy dosage. 50 Gy was the median WBI dosage (range 40.05-50.4 Gy). There were no grade 4 adverse events for any patients in. Toxicities following surgery were minimal. There were only one patient with grade 3 toxicity (radiation dermatitis) to observe. Five tumor bed recurrences and two contralateral breast incident each occurred.

CONCLUSION

This work adds to the preliminary evidence already in the literature and supports the use of IORT in boost settings. When randomized trials like TARGIT-B are eventually published, these hopeful findings should be prospectively evaluated.

Workflow optimization of brachytherapy-based very accelerated partial breast irradiation

PURPOSE

For low-risk breast cancer, accelerated partial breast irradiation (APBI) is a level 1 evidence procedure. Brachytherapy based very APBI (vAPBI) makes it possible to perform adjuvant irradiation in 4 to 1 fraction. However, vAPBI organization is critical. The aim of this technical note is to report on its optimization.

METHODS AND MATERIALS

To offer to low-risk breast cancer patient an efficient, simple, rapid adjuvant irradiation with a reduced number of hospital visits, a new organization of vAPBI based on a single fraction was established, merging all the different steps (from first consultation to irradiation) into a 4-5-consecutive-hour period. This therapeutic program was developed in strong collaboration with radiation oncologists, medical physicists, radiation therapists, and the medical secretary.

RESULTS

After the validation of adjuvant breast irradiation, the patient was offered a telemedicine consultation with the radiation oncologist. Then, the day of vAPBI, the patient arrived at the brachytherapy unit at 08:00 AM for an in-person consultation followed by a preimplant CT scan (defining catheter number and position). After breast local anesthesia, catheter placement was performed followed by a postimplant CT scan for planning purposes. A total dose of 16 Gy in 1 fraction was delivered before removing the catheters. The patient was discharged from the brachytherapy unit around 12:30 PM with an upcoming surveillance consultation date.

CONCLUSIONS

VAPBI organization optimization makes it possible to propose a short 5-h procedure from medical consultation to treatment with only one round trip. Strict organization among staff is required.

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.

The role of the radiation therapy breast boost in the 2020s

Given that most local relapses of breast cancer occur proximal to the original location of the primary, the delivery of additional radiation dose to breast tissue that contained the original primary cancer (known as a "boost") has been a standard of care for some decades. In the context of falling relapse rates, however, it is an appropriate time to re-evaluate the role of the boost. This article reviews the evolution of the radiotherapy boost in breast cancer, discussing who to boost and how to boost in the 2020s, and arguing that, in both cases, less is more.

Modern Tools for Modern Brachytherapy

This review aims to showcase the brachytherapy tools and technologies that have emerged during the last 10 years. Soft-tissue contrast using magnetic resonance and ultrasound imaging has seen enormous growth in use to plan all forms of brachytherapy. The era of image-guided brachytherapy has encouraged the development of advanced applicators and given rise to the growth of individualised 3D printing to achieve reproducible and predictable implants. These advances increase the quality of implants to better direct radiation to target volumes while sparing normal tissue. Applicator reconstruction has moved beyond manual digitising, to drag and drop of three-dimensional applicator models with embedded pre-defined source pathways, ready for auto-recognition and automation. The simplified TG-43 dose calculation formalism directly linked to reference air kerma rate of high-energy sources in the medium water remains clinically robust. Model-based dose calculation algorithms accounting for tissue heterogeneity and applicator material will advance the field of brachytherapy dosimetry to become more clinically accurate. Improved dose-optimising toolkits contribute to the real-time and adaptive planning portfolio that harmonises and expedites the entire image-guided brachytherapy process. Traditional planning strategies remain relevant to validate emerging technologies and should continue to be incorporated in practice, particularly for cervical cancer. Overall, technological developments need commissioning and validation to make the best use of the advanced features by understanding their strengths and limitations. Brachytherapy has become high-tech and modern by respecting tradition and remaining accessible to all.

Low doses to the heart in daily practice for treating left-sided breast cancer using accelerated partial-breast irradiation by multicatheter brachytherapy and deep-inspiration breath-hold using a SIB

PURPOSE

The aim of this study was to analyze the heart dose for left-sided breast cancer that can be achieved during daily practice in patients treated with multicatheter brachytherapy (MCBT) accelerated partial-breast irradiation (APBI) and deep-inspiration breath-hold (DIBH) whole-breast irradiation (WBI) using a simultaneous integrated tumor bed boost (SIB)-two different concepts which nonetheless share some patient overlap.

MATERIALS AND METHODS

We analyzed the nominal average dose (Dmean) to the heart as well as the biologically effective dose (BED) and the equivalent dose in 2‑Gy fractions (EQD2) for an α/β of 3 in 30 MCBT-APBI patients and 22 patients treated with DIBH plus SIB. For further dosimetric comparison, we contoured the breast planning target volume (PTV) in each of the brachytherapy planning CTs according to the ESTRO guidelines and computed tangential field plans. Mean dose (Dmean), EQD2 Dmean, and BED Dmean for three dosing schemes were calculated: 50 Gy/25 fractions and two hypofractionated regimens, i.e., 40.05 Gy/15 fractions and 26 Gy/5 fractions. Furthermore, we calculated tangential field plans without a boost for the 22 cases treated with SIB with the standard dosing scheme of 40.05 Gy/15 fractions.

RESULTS

MCBT and DIBH radiation therapy both show low-dose exposure of the heart. As expected, hypofractionation leads to sparing of the heart dose. Although MCBT plans were not optimized regarding dose to the heart, Dmean differed significantly between MCBT and DIBH (1.28 Gy vs. 1.91 Gy, p < 0.001) in favor of MCBT, even if the Dmean in each group was very low. In MCBT radiation, the PTV-heart distance is significantly associated with the dose to the heart (p < 0.001), but it is not in DIBH radiotherapy using SIB.

CONCLUSION

In daily practice, both DIBH radiation therapy as well as MCBT show a very low heart exposure and may thus reduce long term cardiac morbidity as compared to currently available long-term clinical data of patients treated with conventional tangential field plans in free breathing. Our analysis confirms particularly good cardiac sparing with MCBT-APBI, so that this technique should be offered to patients with left-sided breast cancer if the tumor-associated eligibility criteria are fulfilled.

Sometimes it is better to just make it simple. De-escalation of oncoplastic and reconstructive procedures

Simple breast conservation surgery (sBCS) has technically advanced onto oncoplastic breast procedures (OBP) to avoid mastectomy and improve breast cancer patients' psychosocial well-being and cosmetic outcome. Although OBP are time-consuming and expensive, we are witnessing an increase in their use, even for cases that could be managed with sBCS. The choice between keeping it simple or opting for more complex oncoplastic procedures is difficult. This review proposes a pragmatic approach in assisting this decision. Medical literature suggests that OBP and sBCS might be similar regarding local recurrence and overall survival, and patients seem to have higher satisfaction levels with the aesthetic outcome of OBP when compared to sBCS. However, the lack of comprehensive high-quality research assessing their safety, efficacy, and patient-reported outcomes hinders these supposed conclusions. Postoperative complications after OBP may delay the initiation of adjuvant RT. In addition, precise displacement of the breast volume is not effectively recorded despite surgical clips placement, making accurate dose delivery tricky for radiation oncologists, and WBRT preferable to APBI in complex OBP cases. With a critical eye on financial toxicity, patient satisfaction, and oncological outcomes, OBP must be carefully integrated into clinical practice. The thoughtful provision of informed consent is essential for decision-making between sBCS and OBP. As we look into the future, machine learning and artificial intelligence can potentially help patients and doctors avoid postoperative regrets by setting realistic aesthetic expectations.

On the implant stability in adaptive multi-catheter breast brachytherapy: Establishment of a decision-tree for treatment re-planning

BACKGROUND AND PURPOSE

To assess implant stability and identify causes of implant variations during high-dose-rate multi-catheter breast brachytherapy.

MATERIALS AND METHODS

Planning-CTs were compared to control-CTs acquired halfway through the treatment for 100 patients. For assessing geometric stability, Fréchet-distance and button-to-button distance changes of all catheters as well as variations of Euclidean distances and convex hulls of all dwell positions were determined. The CTs were inspected to identify the causes of geometric changes. Dosimetric effects were evaluated by target volume transfers and re-contouring of organs at risk. The dose non-uniformity ratio (DNR), 100% and 150% isodose volumes (V₁₀₀ and V₁₅₀), coverage index (CI), and organ doses were calculated. Correlations between the examined geometric and dosimetric parameters were assessed.

RESULTS

Fréchet-distance and dwell position deviations >2.5 mm as well as button-to-button distance changes >5 mm were detected for 5%, 2%, and 6.3% of catheters, but for 32, 17, and 37 patients, respectively. Variations occurred enhanced in the lateral breast and close to the ribs, e.g. due to different arm positions. Only small dosimetric effects with median DNR, V₁₀₀, and CI variations of -0.01 ± 0.02, (-0.5 ± 1.3)ccm, and (-1.4 ± 1.8)% were observed in general. Skin dose exceeded recommended levels for 12 of 100 patients. Various correlations between geometric and dosimetric implant stability were found, based on which decision-tree regarding treatment re-planning was established.

CONCLUSION

Multi-catheter breast brachytherapy shows a high implant stability in general, but considering skin dose changes is important. To increase implant stability for individual patients, we plan to investigate patient immobilization aids during treatments.

Ten-year results of hypofractionated whole breast radiotherapy and intraoperative electron boost in premenopausal women

AIM

To evaluate outcome of intraoperative electron boost (IOERT) and hypofractionated whole breast irradiation (HWBI) for breast cancer (BC) in young women.

METHODS AND MATERIALS

Women aged ≤ 48 with pT1-2 N0-1 BC received 12 Gy IOERT boost during conservative surgery followed by 3-dimensional conformal HWBI in 13 fractions (2.85 Gy/die). Local relapses (LR) and survival (disease-free, DFS; specific, BCSS; overall, OS) were analyzed.

RESULTS

481 consecutive BC patients, mostly node negative, with median age of 42 were treated between 2004 and 2014. Median tumor size was 1.48 cm and median IOERT collimator was 4 cm. After 25-day mean interval, HWBI was delivered. At a median follow-up of 9.6 years, there were 23 LRs (4.8 %, 9 of which were in the boost region). Ten-year LR cumulative incidence was 4.1 % (95 %CI, 2.5-6.3). Over time, local control rate decreased for Luminal A and HER2 positive with negative hormonal receptors, while remained steady for triple negative. At multivariate analysis, LR predictors included age < 40, extensive intraductal component and the use of 4-cm IOERT collimator size. Ten-year survival outcomes were as follows: DFS 80.0 % (95 % CI, 75.8-83.5), BCSS 97.5 % (95 % CI, 95.5-98.6 %), OS 96.5 % (95 % CI, 94.3-97.9). Luminal B HER2 negative had the worse survival outcomes. Perioperative complications were uncommon (16.4 %), acute toxicity was mild (<2% Grade 3), but moderate/severe fibrosis was described in 40.8 % of the cases. Cosmesis was scored as excellent/good in 86 % of the cases.

CONCLUSIONS

ELIOT boost and HWBI achieved an excellent local control at the cost of tumor bed fibrosis. IOERT boost dose lower than 12 Gy is advisable.

The comparison of transforming growth factor beta-1 serum levels in early-stage breast cancer patients treated with external beam whole breast irradiation plus boost versus interstitial brachytherapy accelerated partial breast irradiation

PURPOSE

Transforming growth factor beta-1 (TGF-β1) is a profibrotic cytokine used as an early biomarker to develop radiation-induced fibrosis (RIF). This study aimed to compare TGF-β1 serum levels in early-stage breast cancer patients treated with whole-breast radiation therapy (WBRT) plus boost versus accelerated partial breast irradiation (APBI) using multicatheter interstitial brachytherapy.

METHODS AND MATERIALS

This clinical trial study was conducted on 20 women with early-stage breast cancer after breast-conserving surgery candidate for adjuvant radiotherapy in Golestan hospital, Ahvaz, in 2021. In one group APBI with high-dose-rate brachytherapy (n = 10), the other group WBRT with external beam radiation plus boost (n = 10) was performed. Serum level of TGF-β1 was evaluated before radiotherapy, immediately after the end of radiotherapy and three months after the end of radiotherapy by Enzyme-linked immunosorbent assay technique (ELISA).

RESULTS

Median serum TGF-β1 level before radiotherapy was not significantly different between the two groups (p = 0.971). In both APBI and WBRT groups, serum TGF-β1 levels significantly decreased immediately after radiotherapy compared to before treatment (p = 0.005 and p = 0.007, respectively); But three months after radiotherapy, serum TGF-β1 levels increased significantly in the WBRT group (40.50 to 77.41 pg/mL; p = 0.017), while no significant change was observed in the APBI group (24.75 to 30.50 pg/mL; p = 0.332).

CONCLUSIONS

Higher TGF-β1 values in the WBRT group after radiotherapy can be used as an early and vital biomarker in this treatment, and this data may corroborate links between TGF-beta1 and fibrosis and fibrosis rates between APBI and WBRT; It also shows the preference for using the brachytherapy technique in this group of patients. However, due to the small number of samples, definitive conclusions require further prospective studies.

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.

The Role of Interstitial Brachytherapy for Breast Cancer Treatment: An Overview of Indications, Applications, and Technical Notes

Simple Summary

Breast cancer is the most common cancer in the female population. Adjuvant radiotherapy has become increasingly important as conservative treatment. Muticatheter interstitial brachytherapy is a type of radiation technique wherein the radioactive sources are directly implanted into or close to the target tissue and may be considered an extremely precise, versatile, and variable radiation technique. Literature data support muticatheter interstitial brachytherapy as the only method with strong scientific evidence to perform partial breast irradiation and reirradiation after previous conservative surgery and external beam radiotherapy. The aim of our work is to provide a comprehensive view of the use of interstitial brachytherapy, with particular focus on the implant description, limits, and advantages of the technique.

Abstract

Breast cancer represents the second leading cause of cancer-related death in the female population, despite continuing advances in treatment options that have significantly accelerated in recent years. Conservative treatments have radically changed the concept of healing, also focusing on the psychological aspect of oncological treatments. In this scenario, radiotherapy plays a key role. Brachytherapy is an extremely versatile radiation technique that can be used in various settings for breast cancer treatment. Although it is invasive, technically complex, and requires a long learning curve, the dosimetric advantages and sparing of organs at risk are unequivocal. Literature data support muticatheter interstitial brachytherapy as the only method with strong scientific evidence to perform partial breast irradiation and reirradiation after previous conservative surgery and external beam radiotherapy, with longer follow-up than new, emerging radiation techniques, whose effectiveness is proven by over 20 years of experience. The aim of our work is to provide a comprehensive view of the use of interstitial brachytherapy to perform breast lumpectomy boost, breast-conserving accelerated partial breast irradiation, and salvage reirradiation for ipsilateral breast recurrence, with particular focus on the implant description, limits, and advantages of the technique.

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.

Artificial intelligence based treatment planning of radiotherapy for locally advanced breast cancer

Background and purpose

Treatment planning of radiotherapy for locally advanced breast cancer patients can be a time consuming process. Artificial intelligence based treatment planning could be used as a tool to speed up this process and maintain plan quality consistency. The purpose of this study was to create treatment plans for locally advanced breast cancer patients using a Convolutional Neural Network (CNN).

Materials and methods

Data of 60 patients treated for left-sided breast cancer was used with a training, validation and test split of 36/12/12, respectively. The in-house built CNN model was a hierarchically densely connected U-net (HD U-net). The inputs for the HD U-net were 2D distance maps of the relevant regions of interest. Dose predictions, generated by the HD U-net, were used for a mimicking algorithm in order to create clinically deliverable plans.

Results

Dose predictions were generated by the HD U-net and mimicked using a commercial treatment planning system. The predicted plans fulfilling all clinical goals while showing small (≤0.5 Gy) statistically significant differences (p < 0.05) in the doses compared to the manual plans. The mimicked plans show statistically significant differences in the average doses for the heart and lung of ≤0.5 Gy and a reduced D2% of all PTVs. In total, ten of the twelve mimicked plans were clinically acceptable.

Conclusions

We created a CNN model which can generate clinically acceptable plans for left-sided locally advanced breast cancer patients. This model shows great potential to speed up the treatment planning process while maintaining consistent plan quality.

The POLO (Partially Omitted Lobe) approach to safely treat in-breast recurrence after intraoperative radiotherapy with electrons

OBJECTIVES

The aim of this study is to evaluate feasibility of salvage 4-week hypofractionated whole breast radiotherapy (WBRT) in patients with in-breast recurrence after receiving intraoperative radiotherapy with electrons (IOERT) for primary breast cancer (BC).

METHODS

BC patients who had repeated quadrantectomy underwent modified WBRT with intensity-modulated radiotherapy using Helical Tomotherapy to underdose the IOERT region. This approach, called POLO (Partially Omitted Lobe), excluded the IOERT volume from receiving the full prescription dose.

RESULTS

Nine patients were treated with this approach, receiving 45 Gy in 20 fractions. A simultaneous integrated boost of 2.5 Gy in 20 fractions was delivered in 6/9 patients. Dose constraints and planning objectives were reported. No severe toxicity was reported while local control and overall survival were 100%.

CONCLUSION

The POLO approach is technically feasible and capable to achieve a significant reduction of radiation dose delivered to the previous treated IOERT area.

ADVANCES IN KNOWLEDGE

The study demonstrates the technical and dosimetric feasibility of conservative salvage whole breast radiotherapy, while sparing the area already treated with IORT, in patients with in-breast recurrence.

Should the management of radiation therapy for breast cancer be standardized? Results of a survey on current French practices in breast radiotherapy

Background

Breast cancer is the most frequent cancer in women in France. Its management has evolved considerably in recent years with a focus on reducing iatrogenic toxicity. The radiotherapy indications are validated in multidisciplinary consultation meetings; however, questions remain outstanding, particularly regarding hypofractionated radiotherapy, partial breast irradiation, and irradiation of the internal mammary chain and axillary lymph node area.

Materials and methods

An online survey was sent to 47 heads of radiotherapy departments in France. The survey consisted of 22 questions concerning indications for irradiation of the supraclavicular, internal mammary and axillary lymph node areas; irradiation techniques and modalities; prescribed doses; and fractionation.

Results

Twenty-four out of 47 centers responded (response rate of 51%). This survey demonstrated a wide variation in the prescribed dose regimen, monoisocentric radiotherapy, and indications of irradiation of the lymph node areas.

Conclusion

This survey provides insight into the current radiotherapy practice for breast cancer in France. It shows the need to standardize practices.

Tricks and tips for target volume definition and delineation in breast cancer: Lessons learned from ESTRO breast courses

Delineation of target and 'organ at risk' volumes is a critical part of modern radiation therapy planning, the next essential step after deciding the indication, patient discussion and image acquisition. Adoption of volume-based treatment planning for non-metastatic breast cancer has increased greatly along with the use of improved planning techniques, essential for modern therapy. However, identifying the volumes on a planning CT is no easy task. The current paper is written by ESTRO's breast course faculty, providing tricks and tips for target volume definition and delineation for optimal postoperative breast cancer irradiation.

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.

Interstitial multicatheter HDR-brachytherapy as accelerated partial breast irradiation after second breast-conserving surgery for locally recurrent breast cancer

Our aim was to evaluate the efficacy and toxicity of interstitial multicatheter high dose rate brachytherapy (imHDR-BRT) as accelerated partial breast irradiation (APBI) after second breast-conserving surgery (BCS) in patients with ipsilateral breast tumor recurrence (IBTR). Between January 2010 and December 2019, 20 patients with IBTR who refused salvage mastectomy (sMT) were treated with second BCS and post-operative imHDR-BRT as APBI. All patients had undergone primary BCS followed by adjuvant external beam radiotherapy. Median imHDR-BRT dose was 32 Gy delivered in twice-daily fractions of 4 Gy. Five-year IBTR-free survival, distant metastasis-free survival (DMFS), overall survival (OS) as well as toxicity and cosmesis were evaluated in the present retrospective analysis. Median age at recurrence and median time from the first diagnosis to IBTR was 65.1 years and 12.2 years, respectively. After a median follow-up of 69.9 months, two patients developed a second local recurrence resulting in 5-year IBTR free-survival of 86.8%. Five-year DMFS and 5-year OS were 84.6% and 92.3%, respectively. Grade 1-2 fibrosis was noted in 60% of the patients with no grade 3 or higher toxicity. Two (10%) cases of asymptomatic fat necrosis were documented. Cosmetic outcome was classified as excellent in 6 (37.5%), good in 6 (37.5%), fair in 3 (18.75%) and poor in 1 (6.25%) patient, respectively. We conclude that imHDR-BRT as APBI re-irradiation is effective and safe for IBTR and should be considered in appropriately selected patients.

Breast cancer

Breast cancer is still the most common cancer worldwide. But the way breast cancer is viewed has changed drastically since its molecular hallmarks were extensively characterised, now including immunohistochemical markers (eg, ER, PR, HER2 [ERBB2], and proliferation marker protein Ki-67 [MKI67]), genomic markers (eg, BRCA1, BRCA2, and PIK3CA), and immunomarkers (eg, tumour-infiltrating lymphocytes and PD-L1). New biomarker combinations are the basis for increasingly complex diagnostic algorithms. Neoadjuvant combination therapy, often including targeted agents, is a standard of care (especially in HER2-positive and triple-negative breast cancer), and the basis for de-escalation of surgery in the breast and axilla and for risk-adapted post-neoadjuvant strategies. Radiotherapy remains an important cornerstone of breast cancer therapy, but de-escalation schemes have become the standard of care. ER-positive tumours are treated with 5-10 years of endocrine therapy and chemotherapy, based on an individual risk assessment. For metastatic breast cancer, standard therapy options include targeted approaches such as CDK4 and CDK6 inhibitors, PI3K inhibitors, PARP inhibitors, and anti-PD-L1 immunotherapy, depending on tumour type and molecular profile. This range of treatment options reflects the complexity of breast cancer therapy today.

Intraoperative radiotherapy boost as part of breast-conservation therapy for breast cancer: a single-institution retrospective analysis

Background

There are currently no data from randomized controlled trials on the use of intraoperative radiotherapy (IORT) as a tumor bed boost as part of a breast-conservation approach for breast cancer. This study retrospectively reviewed the safety and efficacy of IORT as a boost treatment at a tertiary cancer center.

Methods

From 2015 to 2019, patients underwent breast-conserving surgery with axillary lymph node staging and a single dose of 20 Gy IORT with 50-kV photons, followed by whole-breast irradiation (WBI) and adjuvant systemic therapy (if applicable). Patients were followed for assessment of acute and late toxicities (using the Common Terminology Criteria for Adverse Events version 5.0) at 3–6-month intervals. Outcomes included ipsilateral (IBTR) and contralateral breast progression-free survival (CBE), distant metastasis-free survival (DMFS), and overall survival (OS).

Results

Median follow-up for the 214 patients was 28 (range 2–59) months. Most patients had T1 disease (n = 124) and were clinically node negative. Only few patients had high-grade and/or triple-negative disease. The vast majority of patients underwent sentinel node biopsy, and 32 (15%) required re-resection for initially positive margins. Finally, all tumor bed margins were clear. Nine (4.2%) and 48 (22.4%) patients underwent neoadjuvant and adjuvant chemotherapy, respectively. WBI was predominantly performed as conventionally fractionated WBI (n = 187, 87.4%), and the median time from BCS to WBI was 54.5 days. IORT was delivered with a single dose of 20 Gy. The median WBI dose was 50 Gy (range 29.4–50.4 Gy). No patients experienced grade 4 events; acute grade 3 toxicities were limited to 17 (8%) cases of radiation dermatitis. Postoperative toxicities were mild. After WBI only one case of late grade ≥ 2 events was reported. There were two recurrences in the tumor bed and one contralateral breast event.

Conclusion

This investigation provides additional preliminary data supporting the using of IORT in the boost setting and corroborates the existing literature. These encouraging results should be prospectively validated by the eventual publication of randomized studies such as TARGIT‑B.

APBI Versus Ultra-APBI in the Elderly With Low-Risk Breast Cancer: A Comparative Analysis of Oncological Outcome and Late Toxicity

PURPOSE

Accelerated partial breast irradiation (APBI) represents a validated technique for low-risk breast cancer. Recently, ultra-APBI (uAPBI) using fewer than 5 fractions was described in the literature. We compared clinical outcomes and late toxicity after APBI or uAPBI in older patients.

METHODS AND MATERIALS

Two cohorts of older patients (aged ≥70 years) with low-risk breast cancer treated with APBI (interstitial brachytherapy) were analyzed retrospectively. A total dose of 34 Gy in10 fractions (APBI) or 16 Gy in 1 fraction (uAPBI) was delivered from 2004 to 2012 and from 2013 to 2018, respectively. Oncologic outcome analyzed the cumulative incidence of local relapse, regional relapse, and distant metastases with disease-free survival, cause-specific survival, and overall survival. Late toxicity and cosmetic results were investigated.

RESULTS

One hundred fifty-seven patients (APBI, n = 109 patients; uAPBI, n = 48 patients) underwent APBI according to the same selection criteria. Apart from the median follow-up (97 vs 72 months for APBI and uAPBI; P < .002), no significant difference was noted between the 2 groups. Regarding 6-year oncologic outcome, no significant difference was observed between APBI and uAPBI for local recurrence (1.3% vs 0%; P = .4), regional recurrence (2.5% vs 2.3%; P = .9), distant metastases (4.3% vs. 2.4%; P = .6), disease-free survival (85.2% vs. 82.2%; P = .8), cause-specific survival (96.7% vs. 96.2%; P = .9), and overall survival (86.7% vs. 82.2%; P = .7). Regarding late toxicity, no significant difference was observed between APBI and uAPBI (total complication number, 45 vs 33%; P = .173) with only grade 1 (88.4% vs. 95%) and grade 2 (11.6% vs. 5%) late toxicities (P = .677). Similarly, no significant difference was observed for excellent/good cosmetic results between the 2 cohorts (P = .98).

CONCLUSIONS

We report the first study comparing APBI versus uAPBI in a cohort of older patients with low-risk breast cancer. No significant difference was found between the 2 treatment groups regarding oncologic outcome, late toxicity, and cosmetic result. uAPBI based on a single fraction of brachytherapy represents an attractive option for therapeutic de-escalation in older patients with breast cancer.

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.

Effective of Pre-operative 2-Deoxy-2-[fluorine-18] fluoro-d-glucose/Positron Emission Tomography/Computed Tomography in the Determination of Boost Volume in Adjuvant Radiotherapy after Breast-conserving Surgery

Objectives:

Determining boost volume (BV) during breast radiotherapy can be challenging at times. Therefore, surgical clips are now being widely used. At times, when surgical clips are inadequate in determining the BV, other additional imaging methods are required. In the present study, we aimed to demonstrate that pre-operative positron emission tomography/computed tomography (PET-CT) can be used to determine the BV after a breast-conversing surgery.

Methods:

We selected thirty patients who underwent breast-conserving surgery with surgical clips and had preoperative Fluorine-18-Fluorodeoxyglucose PET (18 FDG PET/CT). The BV in planning tomography (CT) and primary tumor volume (TV) in pre-operative F-18 FDG PET/CT was contoured by a radiation oncologist. These two volumes were superposed using rigid image fusion. In every patient, two BVs were measured. The mean shift between the two volumes by the calculation of the center of mass and percentage of the PET-CT TV (PET-CT TV) in planning the BV (planning target volume [PTV]-BV) was calculated.

Results:

The median age was 52 years (range 25–72 years). The pre-operative PET-CT TV median was 8.89 cm³ (range 1.00–64.30 cm³). The median PTV-BV was 62.92 cm³ (12.57–123.07 cm³). The median shifts between the center of volumes were 1.76 cm (range 0.90–3.50) in X(coronal), 1.73 cm (range 0.60–3.60) in the Y(axial), and 1.20 cm (0.40–2.80) in the Z(sagittal) directions, respectively. The shifts in these three planes were determined to be statistically significant (p<0.001). The percent volume of PET-CT TV included PTV TV, ranging from 35% to 100% (mean 54%, standard deviation 29.53) and 100% in two out of 31 patients.

Conclusion:

Our study has shown that pre-operative PET-CT cannot be used to determine the BV in patients who replaced surgical clips and had undergone breast-conserving surgery. To define a more accurate BV, surgical clips should be placed in four planes, and more PTV margins should be given in treatment planning.

Can we rely on surgical clips placed during oncoplastic breast surgery to accurately delineate the tumor bed for targeted breast radiotherapy?

PURPOSE

Oncoplastic breast surgery (OBS) is gaining popularity among surgeons for breast-conserving surgery treatments. OBS relies on complex relocation and deformation of breast tissue involving the tumor bed (TB). In this study, we investigate the validity of using surgical clips with OBS for accurate TB delineation in adjuvant, targeted breast radiotherapy.

METHODS

Different OBS techniques were simulated on realistic breast phantoms. Surgical clips were used to demarcate the TB. Following tumor resection and closure, the true TB (TB_True) was extracted. Each phantom was CT imaged at several phases of surgery in order to record pre- and post-OBS closure surgical clip displacements. Two senior radiation oncologists (ROs) were asked to delineate TBs on CTs by relying on surgical clips placed as per standard protocol, and by referring to operative notes. Their original contours, as well as those expanded using 5-15 mm margins, were compared with the accurate TB_True using the dice similarity coefficient (DSC), Hausdorff Distance (HD), and over- and under-contoured volumes. Inter- and intra-RO contour agreements were also evaluated.

RESULTS

Post-OBS surgical clips were significantly displaced outside the original breast quadrant. Inter- and Intra-RO TB contours were consistent, yet systematically differed from TB_True (DSC values range = 0.38 to 0.69, and maximum HD range = 17.8 mm to 38.0 mm). Using expansion margins did not improve contour congruence and caused significant over-contoured volumes.

CONCLUSION

Following OBS, surgical clips alone are not reliable radiographic surrogates of TB locations and accurate TB delineation is challenging. For complex OBS cases, indication of any type of partial breast irradiation is very questionable.

Advances in stent therapy for malignant biliary obstruction

Malignant biliary obstruction (MBO), result of pancreatobiliary diseases is a challenging condition. Most patients with MBO are inoperable at the time of diagnosis, and the disease is poorly controlled using external-beam radiotherapy and chemotherapy. Biliary stent therapy emerged as a promising strategy for alleviating MBO and prolonging life. However, physicians find it difficult to determine the optimal type of biliary stent for the palliation of MBO. Here, we review the safety and efficacy of available biliary stents, used alone or in combination with brachytherapy, photodynamic therapy and advanced chemotherapeutics, in patients with pancreatobiliary malignancies and put forward countermeasures involving stent obstruction. Furthermore, 3D-printing stents and nanoparticle-loaded stents have broad application prospects for fabricating tailor-made biliary stents.

Transposition flap for the oncoplastic reconstruction of outer quadrant breast defects

Plastic surgical principles are incorporated with breast conservation surgery (BCS) for cancer to improve aesthetic outcomes. In developing countries, average tumour size is larger at presentation resulting in larger resections often, including overlying skin. LD flap has been the workhorse of partial breast reconstruction. We present an easy and effective alternative to LD flap for carefully selected cases of outer quadrant breast tumours. We report 41 cases of local transposition flap from the lateral chest wall for oncoplastic restoration post BCS, performed between January 2016 and February 2020, at our institution. The median age was 49 years (28-63). Twenty-six patients underwent upfront surgery and 15 after neoadjuvant chemotherapy (NACT). The average pathological tumour size was 2.9 cm (median 2.7 and range 1.1-6) and 1.5 cm (median 1.8 and range 0-3.5) for upfront and post-NACT groups, respectively. The median volume of the resected specimen was 277.8 ml and 253.2 ml for upfront and post-NACT groups, respectively. Three patients (7.5%) had a microscopic positive margin requiring margin revision. Three (7.5%) patients had post-operative minor wound complications and were managed conservatively. At a median follow-up of 14 months (1-36), only 2/19 (10.5%) patients had clinical fat necrosis. Local transposition flap from the lateral chest wall based on dermal and subdermal plexus, carefully designed in selected patients, can be used effectively for the reconstruction of outer quadrant breast defects. It is easy to learn, offers good cosmetic outcome, avoids the morbidity and time of LD flap and saves LD flap for future use.

The contribution of surgical clips for optimizing highly-conformal image-guided flank irradiation in pediatric renal tumors: A single center experience

BACKGROUND AND AIMS

Two-opposing photon beams are considered standard of care for flank irradiation in pediatric patients with renal tumors. Nowadays, Image-Guided Radiotherapy (IGRT) techniques allow high-precision dose delivery to complex flank target volumes taking into account postoperative organ shifts and tumor bed motion. This study examines the contribution of a lateral and superior surgical clip on flank target volume delineation intended for IGRT.

METHODS

Between 01-2015 and 09-2019, 30/162 newly-diagnosed pediatric patients with renal tumors, lateral/superior surgical clips (n = 30/30) and available 4D-CT-scans (n = 27/30), underwent postoperative flank irradiation. The lateral and superior clip, as respective markers for the lateral tumor extension and intrafraction motion, were analyzed. The positive and negative values depict the lateral/dorsal/cranial or the medial/ventral/caudal direction, respectively. Planning target volumes (PTV) were generated based on lateral clips (PTV_latclip), superior clips with 4D-CT technology (PTV_supclip), and both clips combined (PTV_combined), and compared to an approach without clips (PTV_noclip).

RESULTS

Indicated by clips, the mean lateral tumor bed extension along the posterior wall was 74° (range: 50°-93°), while mean intrafraction motion was +1.2 mm (range: -1.8/+4.8 mm), +0.6 mm (range: +0.6/+4.9 mm), -0.3 mm (range: -3.8/+0.7 mm) in craniocaudal, ventrodorsal, mediolateral direction, respectively. The median PTV_noclip (556 mL) was statistically different from the median PTV_latclip (454 mL, p = <0.01), median PTV_supclip (373 mL, p = <0.01) and median PTV_combined (348 mL p = <0.01).

CONCLUSION

In pediatric patients with renal tumors, surgical clips at the lateral and superior border of the tumor bed can optimize flank target volume delineation and, consequently, reduce the normal tissue volume receiving high-dose irradiation when IGRT techniques are applied.

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.

Accelerated partial breast irradiation in the elderly: 8-year oncological outcomes and prognostic factors

PURPOSE

The purpose of the study is to evaluate long-term clinical outcomes and prognostic factors after accelerated partial breast irradiation (APBI) in the elderly using high-dose-rate interstitial multicatheter brachytherapy (HIBT).

METHODS AND MATERIALS

Between 2005 and 2018, 109 patients underwent APBI using HIBT (34 Gy/10f/5d or 32 Gy/8f/4d). Based on a prospective database, outcomes were retrospectively analyzed (local relapse-free survival, metastatic-free survival, specific survival (SS), and overall survival (OS)). Prognostic factors were investigated. Late toxicity and cosmetic evaluation were reported.

RESULTS

With a median followup of 97 months [7-159], median age was 81.7 years [58-89]. In accordance with the GEC-ESTRO APBI classification, 72.5%, 11.9%, and 15.6% were classified as low, intermediate, and high risk, respectively. The histological type was mainly invasive ductal carcinoma (87.1%). The median tumor size was 10 mm [range 1-35]. Eight-year local relapse-free survival, SS, and OS were 96.7% [95% confidence interval (CI) [0.923; 1]), 96.7% [95% CI [0.924; 1], and 72% [95% CI [0.616; 0.837], respectively. In univariate analysis, APBI classification was not considered as prognostic factor, whereas molecular classification was prognostic factor for OS (p < 0.0001), SS (p = 0.007), and metastatic-free survival (p = 0.009) but not for local recurrence (p = 0.586). No Grade ≥3 late toxicity was observed, whereas 61 patients (88.4%) and 8 patients (11.6%) presented Grade 1 and 2 toxicities, respectively. The cosmetic outcome was excellent/good for 96.4%.

CONCLUSIONS

Long-term followup confirms that HIBT is safe and effective for elderly early breast cancer. Our results suggest that selected elderly women presenting with high-risk breast cancer could be also considered for APBI.

Matched-pair dosimetric comparison of cardiac radiation exposure between deep-inspiration breath-hold whole-breast radiation therapy with Active Breathing Coordinator and interstitial multicatheter high-dose-rate brachytherapy as accelerated partial breast irradiation in adjuvant treatment of left-sided breast cancer after breast-conserving surgery

BACKGROUND AND PURPOSE

To compare dosimetrically the radiation exposure to heart, left ventricle (LV), and left anterior descending artery (LAD) between whole-breast radiotherapy (WBRT) with Active Breathing Coordinator (ABC; ABC-WBRT) and interstitial multicatheter high-dose-rate (HDR) brachytherapy as accelerated partial breast irradiation (ABPI; imHDR-APBI) for left-sided breast cancer (BCA) after breast-conserving surgery (BCS).

MATERIALS AND METHODS

Between January 2016 and December 2019, 32 and 20 patients were treated with ABC-WBRT (63 Gy/2.25 Gy) and imHDR-APBI (32 Gy/4 Gy), respectively. Among them a matched-pair analysis was performed according to tumor location (clock position) before BCS as well as planning target volume of imHDR-APBI and boost volume of ABC-WBRT. This yielded 17 pairs of patients for whom dosimetric parameters for heart, LV, and LAD were evaluated. The Mann-Whitney test was used for comparison after adjusting for equivalent dose in 2‑Gy fractions (EQD2). In addition, a second analysis of ABC-WBRT to 40.05 Gy in 15 fractions was performed in order to account for the EQD2 difference between the 63-Gy ABC-WBRT and the imHDR-APBI protocol.

RESULTS

Tumor location for the 17 pairs of patients relative to breast quadrant was as follows: upper outer 8, lower outer 5, upper inner 3, and lower inner 1. There was no difference regarding mean heart dose (MHD) and V5, whereas D25%, D45%, V10, and V25 significantly favored imHDR-APBI. Likewise, mean dose- and V5-LV did not differ, while Dmax- and V23-LV were significantly higher for ABC-WBRT. For LAD, Dmax, D25%, and V30 significantly favored imHDR-APBI without differences for mean dose and V40. When comparing imHDR-APBI with the 40.05 Gy ABC-WBRT schedule, MHD and mean dose LV were significantly lower in favor of ABC-WBRT.

CONCLUSION

ABC-WBRT and imHDR-APBI yield similar low heart and LV exposure for left-sided BCA after BCS, whereas LAD can be better spared with imHDR-APBI.

What is the dosimetric impact of isotropic vs anisotropic safety margins for delineation of the clinical target volume in breast brachytherapy?

PURPOSE

The purpose of the study was to report dosimetric differences for breast brachytherapy plans optimized for clinical target volume (CTV) generated using conventional isotropic expansion of tumor bed volume (TBV) and Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) recommendations to expand the TBV anisotropically to achieve a total safety margin of 2 cm (resection margin size + added safety margin).

METHODS

Institutional records of 100 patients who underwent accelerated partial breast irradiation using multicatheter interstitial brachytherapy from May 2015 to March 2020 were reviewed retrospectively. Two sets of CT-based plans were made, one with 1-cm isotropic margins around the tumor bed (CTV_ISO) and the other with anisotropic margins (CTV_GEC). Plans were evaluated and compared using the American Brachytherapy Society and GEC-ESTRO guidelines.

RESULTS

The median TBV was 36.97 cc. The median margin widths were as follows: anterior 1.2, posterior 1.0, superior 1.0, inferior 0.9, medial 1.2, and lateral 1.2 cm. The mean tumor bed coverage index was 0.94; 0.93 [p.066], the CTV coverage index 0.86; 0.84 [p 0.001], the dose homogeneity index (DHI) 0.77; 0.75 [p < 0.001] and the conformity index 0.66; 0.64 [p < 0.001] in CTV_ISO and CTV_GEC plans, respectively. In smaller volume implants (TBV< 35 cc), the DHI was 0.76; 0.75 [p 0.008] and the conformity index was 0.66; 0.62 [p < 0.001], whereas in larger volumes >35 cc, the CTV coverage index was 0.86; 0.84 [p 0.003] and the DHI 0.78; 0.76 [p 0.001] in CTV_ISO and CTV_GEC plans, respectively.

CONCLUSIONS

In this cohort of patients who underwent accelerated partial breast irradiation, plans with anisotropic margins had lower conformity, the impact of which was predominantly seen in smaller implants. Rest of the dosimetric constraints were achieved in both the plans as per the American Brachytherapy Society and GEC-ESTRO guidelines.

No Difference in Overall Survival and Non-Breast Cancer Deaths after Partial Breast Radiotherapy Compared to Whole Breast Radiotherapy-A Meta-Analysis of Randomized Trials

Purpose/objective: Adjuvant radiotherapy after breast conserving surgery is the standard approach in early stage breast cancer. However, the extent of breast tissue that has to be targeted with radiation has not been determined yet. Traditionally, the whole breast was covered by two opposing tangential beams. Several randomized trials have tested partial breast irradiation (PBI) compared to whole breast irradiation (WBI) using different radiation techniques. There is evidence from randomized trials that PBI might result in lower mortality rates compared to WBI. We aimed to reassess this question using current data from randomized trials. 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 overall survival (OS), breast cancer-specific survival (BCSS), and non-breast cancer death (NBCD) as investigated endpoints. Analysis of subgroups using different radiation techniques was intended. We used hazard ratios (HR) and risk differences (RD) to estimate pooled effect sizes. Statistical analysis was performed using the inverse variance heterogeneity model. Results: We identified eleven studies randomizing between PBI and WBI. We did not find significant differences in OS (n = 14,070; HR = 1.02; CI-95%: 0.89–1.16; p = 0.810, and n = 15,203; RD = −0.001; CI-95%: −0.008–0.006; p = 0.785) and BCSS (n = 15,203; RD = 0.001; CI-95%: −0.002–0.005; p = 0.463). PBI also did not result in a significant decrease of NBCD (n = 15,203; RD = −0.003; CI-95%: −0.010–0.003; p = 0.349). A subgroup analysis by radiation technique also did not point to any detectable differences. Conclusion: In contrast to a previous assessment of mortality, we could not find a detrimental effect of WBI on OS or NBCD. A longer follow-up might be necessary to fully assess the long-term mortality effects of PBI compared to WBI.

The use of hyaluronic acid hydrogel as a tumour bed marker in breast-conserving therapy

PURPOSE

To evaluate usefulness of hyaluronic acid (HA) hydrogel as a tumour bed marker in breast conserving therapy (BCT). To analyze inter- (Inter-OV) and intraobserver (Intra-OV) variability of contouring boost target volume (CTV_boost) in external beam radiotherapy (EBRT).

MATERIALS AND METHODS

Thirty-two patients in the HA group and 30 patients in the control group with an early stage breast cancer were included in the study. During the surgery 1-3 ml of HA hydrogel was injected into breast to mark the tumour bed for every patient in the HA group. Moreover, surgical clips were placed underneath the lumpectomy cavity. Patients in the control group were marked only by metal markers. Three radiation oncologists delineated CTV_boost twice for every patient. Three parameters were calculated to quantify contouring variability: coefficient of variation for volumes (COV_V), center of mass displacement (CoMd) and conformity index (CI).

RESULTS

There were no significant differences between mean values of COV_V for HA and control group, neither for Intra-OV (0.14 vs 0.13) nor Inter-OV (0.19 vs 0.18) calculations. The mean CoMd were 6.1 mm and 9.1 mm for Inter-OV calculations and 3.9 mm and 6.4 mm for Intra-OV in the HA and the control group respectively. The mean CI for Intra-OV improved from 0.61 to 0.65 and from 0.47 to 0.56 for Inter-OV in the control and HA group respectively.

CONCLUSION

HA hydrogel used as a tumour bed marker improves tumour bed visibility and reduces inter- and intraobserver variability of EBRT boost target volume delineations.

Optimizing MR-Guided Radiotherapy for Breast Cancer Patients

Current research in radiotherapy (RT) for breast cancer is evaluating neoadjuvant as opposed to adjuvant partial breast irradiation (PBI) with the aim of reducing the volume of breast tissue irradiated and therefore the risk of late treatment-related toxicity. The development of magnetic resonance (MR)-guided RT, including dedicated MR-guided RT systems [hybrid machines combining an MR scanner with a linear accelerator (MR-linac) or 60Co sources], could potentially reduce the irradiated volume even further by improving tumour visibility before and during each RT treatment. In this position paper, we discuss MR guidance in relation to each step of the breast RT planning and treatment pathway, focusing on the application of MR-guided RT to neoadjuvant PBI.

High-dose-rate Brachytherapy as Adjuvant Local rEirradiation for Salvage Treatment of Recurrent breAst cancer (BALESTRA): a retrospective mono-institutional study

PURPOSE

To evaluate clinical results of catheter-based interstitial high-dose-rate (HDR) brachytherapy (BT) as adjuvant treatment in previously irradiated recurrent breast cancer.

MATERIAL AND METHODS

Between January 2011 and September 2015, 31 consecutive patients with histologically confirmed recurrent breast cancer after conservative surgery and conventional whole breast radiotherapy, were retreated with a second conservative surgical resection and reirradiated with adjuvant interstitial HDR-BT. None of the brachytherapy implant was performed during the quadrantectomy procedure. A dose of 34 Gy in 10 fractions, 2 fractions per day, with a minimal interval of 6 hours was delivered.

RESULTS

At the time of the implant, the median age of patients was 59.7 years (range, 39.3-74.9 years). The median time from first treatment until BT for local recurrence was 11.9 years (range, 2.5-27.8 years). The median interval between salvage surgery and BT was 3.6 months (range, 1-8.2 months). No acute epidermitis or soft tissue side effects higher than grade 2 were recorded, with good cosmetic results in all patients. Most of the patients presented grade 1-2 late side effects. Only one patient developed grade 3 liponecrosis. After a median follow-up of 73.7 months (range, 28.8-102.4 months), the overall survival and cancer specific survival were 87.1% and 90.3%, respectively; 5-year local control and 5-year progression-free survival rate were 90.3% and 83.9%, respectively.

CONCLUSIONS

Our preliminary analysis showed that HDR-BT is a feasible treatment for partial breast reirradiation offering very low complications rate and fast procedure. Higher patients' cohort is warranted in order to define the role of this treatment modality in the breast conservative management of local recurrence.