Accelerated Partial Breast Irradiation in Clinical Practice

Post IORT seroma complication in breast cancer surgery

Background:

Intraoperative radiotherapy (IORT) has gained popularity over recent years due to its impact on shortening the radiotherapy treatment time for early breast cancer. It has certainly proven effective as an exclusive treatment or when combined with whole breast irradiation (WBIR). Seroma is a common non-life-threatening complication that may delay treatment and impose challenges on radiological diagnostic follow-up.

Aim:

To review and compare the occurrence of seroma in patients who received exclusive IORT or when combined with WBIR and to outline the diagnostic challenges encountered during radiological follow-up.

Materials and methods:

Based on strict selection criteria, all eligible patients who received IORT ± WBIR treatment between 2012 and 2019 in a university hospital setting were included. Demographic data, histological diagnosis, tumour size, tumour grade, lymphovascular invasion, nodal status, receptor status, treatment with neoadjuvant hormonal chemotherapy, applicator size, dose used, duration of radiotherapy treatment, timing of seroma development and duration of seroma were documented. Both clinical and radiological follow-up were exercised in all patients.

Results:

The total number of patients treated with breast conserving surgery (BCS) and IORT was 86. Age ranged between 31 and 75 years with the median age of 51 years. Patients treated exclusively with IORT were 39 (45%) while those who received the IORT as a boost were 47 (55%). Seroma was observed in 39(45%) of both IORT and IORT\WBIR patients. Those included 15(38%) of the exclusive IORT treated patients and 24 (62%) of those treated as a boost. Duration of asymptomatic seroma ranged from 6 months to 6 years. Repeated aspiration was performed in 2 (5%) patients. Postoperative seroma occurred independent of age histological diagnosis, tumour size, tumour grade, lymphovascular invasion, nodal status, receptor status, treatment with neoadjuvant hormonal\chemotherapy, applicator size, dose used or duration of radiotherapy treatment. All reviewed patients have shown increased risk of developing seroma; however, an increased incidence of seroma in the IORT + WBIR treated patients was higher than those who received exclusive IORT treatment.

Conclusion:

Postoperative seroma is a common non-life-threatening entity that occasionally may lead to delay in the subsequent treatment plan. IORT is a safe modality with many benefits; however, it may increase the risk of seroma formation independent of the clinical parameters. Promoting the expertise in post IORT breast imaging aids in overcoming diagnostic challenges.

Definitive single fraction stereotactic ablative radiotherapy for inoperable early-stage breast cancer: A case report

We review a case of inoperable early stage breast cancer treated definitively with the use of stereotactic ablative radiotherapy (SABR). A 57-year-old female with a history of decompensated cirrhosis with early stage breast cancer was treated with 25 Gy in one fraction. At her 7-month follow up visit, there was a complete resolution of disease on imaging. This case represents a novel approach for the treatment of breast cancer with SABR when surgery is contraindicated.

Preoperative radiotherapy: A paradigm shift in the treatment of breast cancer? A review of literature

The standard of care for early-stage breast cancer (BC) consists of breast-conserving surgery followed by postoperative irradiation. Recently, the concept of changing the usual sequence of treatment components in BC RT has been investigated. Potential advantages of preoperative RT in BC include a possible tumor downstaging with improved surgical cosmetic outcomes, accurate tumor site identification and better target volume delineation. Furthermore, preoperative RT could serve as a tool for treatment stratification for de-escalation of treatments in the event of pathological complete response. The present literature review analyzed the available clinical data regarding the potential impact of preoperative RT. Overall, available clinical evidence of preoperative RT in BC remains limited, deriving mostly from retrospective case series. Nevertheless, the experiences prove the feasibility of the preoperative RT approach and confirm the efficacy in almost all analyzed studies, including experiences using higher prescription RT doses or RT in combination with systemic therapy.

Recent Developments in Radiation Oncology: An Overview of Individualised Treatment Strategies in Breast Cancer

Radiation therapy (RT) for breast cancer has dramatically changed over the past years, leading to individualized risk-adapted treatment strategies. Historically, the choice of RT regimen was limited to conventional fractionation protocols using standard tangential fields. Nowadays, technological and technical improvements in modern RT have added a variety of other RT modalities, different fractionation schedules, and individualised treatment volumes to the portfolio of breast RT. This review aims to give a short overview on the main topics which have recently found their way into clinical practice: hypofractionated treatment protocols, accelerated partial breast irradiation (APBI) for low-risk patients, deep inspiration breath hold (DIBH) for maximal heart protection, extent of regional nodal irradiation for high-risk patients, and the implementation of new radiation techniques such as intensity modulated RT (IMRT) and volumetric modulated RT (VMAT).

Precision Medicine for Breast Cancer: The Paths to Truly Individualized Diagnosis and Treatment

Precision medicine in oncology seeks to individualize each patient's treatment regimen based on an accurate assessment of the risk of recurrence or progression of that person's cancer. Precision will be achieved at each phase of care, from detection to diagnosis to surgery, systemic therapy, and radiation therapy, to survivorship and follow-up care. The precision arises from detailed knowledge of the inherent biological propensities of each tumor, rather than generalizing treatment approaches based on phenotypic, or even genotypic, categories. Extensive research is being conducted in multiple disciplines, including radiology, pathology, molecular biology, and surgical, medical, and radiation oncology. Clinical trial design is adapting to the new paradigms and moving away from grouping heterogeneous patient populations into limited treatment comparison arms. This review touches on several areas invested in clinical research. This special issue highlights the specific work of a number of groups working on precision medicine for breast cancer.

Analysis of the variability among radiation oncologists in delineation of the postsurgical tumor bed based on 4D-CT

OBJECTIVE

This study investigated interobserver and intraobserver variability in radiation oncologists' definition of the tumor bed (TB) after breast-conserving surgery (BCS).

RESULTS

The TB volume, CVS and number of surgical clips were not significantly related to intraobserver variability. Moreover, no correlation was noted between CT slice thickness and interobserver variability (Δinter, DSCinter) in TB delineation, and no significant difference was noted among the three groups. The TB volume was negatively correlated with Δinter. DSCinter improved significantly with increased TB volume and decreased Δinter. DSCinter also increased significantly in patients with a CVS of 3 to 5 compared with patients with a CVS of 1 to 2. DSCinter was thus positively correlated with the CVS, with a correlation coefficient of 0.451. The use of 7 to 9 surgical clips neither decreased Δinter nor increased DSCinter.

MATERIALS AND METHODS

Five or more surgical clips were placed at the TB during lumpectomy. The TB was delineated on the end expiration scan. The data were stratified based on the cavity visualization score (CVS), CT slice thickness and surgical clip number. The Dice similarity coefficient (DSC) and inter(intra)observer variability (Δinter and Δintra) in different groups were evaluated and compared.

CONCLUSIONS

Inter(intra)observer variability in TB delineation was decreased for breast cancer patients implanted with 5 or more surgical clips in the cohort with a higher CVS and a larger TB. The use of more than 6 surgical clips did not significantly improve TB delineation, so 5 to 6 surgical clips are likely adequate to delineate the TB.

Intra-operative radiotherapy management for breast cancer treatment in patients with pseudoxanthoma elasticum: A case report

Pseudoxanthoma elasticum is a systemic metabolic disease presenting calcifications and progressive fragmentation of elastic fibers. Actually, no targeted therapies are available for the treatment; only prevention of complications is possible. Classically, pseudoxanthoma elasticum is a "benign" disease, without cancer association. Herein, we reported a singular association of pseudoxanthoma elasticum with breast carcinoma, describing the clinical management, in particular intra-operative treatment, focusing on intra-operative radiotherapy since no specific guidelines are available in literature.

Keynote Address at the American Society of Breast Surgeons 18th Annual Meeting : Current and Future Application of Intraoperative Radiotherapy (IORT) in the Curative and Palliative Treatment of Breast Cancer

Intraoperative radiotherapy (IORT) is increasingly used worldwide. Breast cancer is the most rapidly growing indication for IORT, approaching 70-80% of cases in most centers. This report reviews the theoretical background and clinical use of IORT for primary and metastasized breast cancer. There are established applications such as tumor bed boost during breast-conserving surgery followed by whole breast radiotherapy or IORT as a form of accelerated partial-breast irradiation (APBI) for selected patients. Novel applications such as IORT for vertebral or brain metastases are presented as well as technological developments, widening the spectrum of potential clinical applications for IORT.

Partial breast irradiation with interstitial multi-catheter high-dose-rate brachytherapy. Long-term results of a phase II prospective study

PURPOSE

We report the long-term results of phase II prospective study with accelerated partial breast irradiation (APBI) using interstitial multi-catheter high-dose-rate brachytherapy.

METHODS

240 patients received APBI (4Gy, twice daily; total dose 32Gy).

RESULTS

Median follow-up was 96months. Recurrences in the treated breast developed in 8 patients (3.3%) at a median of 73months after APBI. The 5- and 10-year cumulative incidences were respectively, 1.8% (95%CI: 0.6-4.3) and 6.6% (95%CI: 2.7-12.9). Regional recurrences developed in 5 patients (2%) at a median of 28months and distant metastases in 8 (3.3%) at a median of 32.5months. Breast cancer specific mortality occurred in 6 patients (2.5%) at a median of 60months. Acute toxicity developed in 71 (29.6%) patients (G1 in 60 and G2 in 11). Almost all were skin toxicity and hematomas. Late toxicity was observed in 90 patients (37.5%), G1 in 97 cases and G2 in 11. Some patients presented with more than one type of toxicity. Teleangectasia and fibrosis were the most common (48 and 44 cases respectively), followed by fat necrosis (in 18 patients) Tamoxifen emerged as the only risk factor for breast fibrosis (p=0.007). Cosmetic results were judged by the physicians as excellent in 174 (83.7%) patients, good in 25 (12%) fair in 8 (3.8%) and poor in 1 (0.5%); 174 patients (83.7%) judged outcomes as excellent, 26 (12.4%) as good, 7 (3.4%) as fair and 1 (0.5%) as poor. Physician/patient agreement was good (weighted k-value 0.72).

CONCLUSIONS

APBI with interstitial multi-catheter brachytherapy was associated with good outcomes, low relapse and toxicity rates. Few events during this long-term follow-up preclude identifying specific features of patients at risk of relapse and illustrate the need for a large data-base.

Current controversies in radiotherapy for breast cancer

Multimodal treatment approaches have substantially improved the outcome of breast cancer patients in the last decades. Radiotherapy is an integral component of multimodal treatment concepts used in curative and palliative intention in numerous clinical situations from precursor lesions such as ductal carcinoma in situ (DCIS) to advanced breast cancer. This review addresses current controversial topics in radiotherapy with special consideration of DCIS, accelerated partial breast irradiation (APBI) and regional nodal irradiation (RNI) and provides an update on the clinical practice guidelines of the Breast Cancer Expert Panel of the German Society of Radiation Oncology (DEGRO).

Biology of high single doses of IORT: RBE, 5 R's, and other biological aspects

Intraoperative radiotherapy differs from conventional, fractionated radiotherapy in several aspects that may influence its biological effect. The radiation quality influences the relative biologic effectiveness (RBE), and the role of the five R’s of radiotherapy (reassortment, repair, reoxygenation, repopulation, radiosensitivity) is different. Furthermore, putative special biological effects and the small volume receiving a high single dose may be important. The present review focuses on RBE, repair, and repopulation, and gives an overview of the other factors that potentially contribute to the efficacy. The increased RBE should be taken into account for low-energy X-rays while evidence of RBE < 1 for high-energy electrons at higher doses is presented. Various evidence supports a hypothesis that saturation of the primary DNA double-strand break (DSB) repair mechanisms leads to increasing use of an error-prone backup repair system leading to genomic instability that may contribute to inactivate tumour cells at high single doses. Furthermore, the elimination of repopulation of residual tumour cells in the tumour bed implies that some patients are likely to have very few residual tumour cells which may be cured even by low doses to the tumour bed. The highly localised dose distribution of IORT has the potential to inactivate tumour cells while sparing normal tissue by minimising the volume exposed to high doses. Whether special effects of high single doses also contribute to the efficacy will require further experimental and clinical studies.

Intraoperative radiotherapy (IORT) as boost in breast cancer

The term IORT (intraoperative radiotherapy) is currently used for various techniques that show huge differences in dose delivery and coverage of the tissue at risk. The largest evidence for boost IORT preceding whole breast irradiation (WBI) originates from intraoperative electron treatments (IOERT) with single doses around 10 Gy. At median follow-up periods at 6 years, outstandingly low local recurrence rates of less than 1% are observed. Higher local relapse rates were described for G3 tumors and triple negative breast cancers as well as for IORT following primary systemic treatment for locally advanced tumors. Even there, long term (>5y) local tumor control rates mostly beyond 95% were maintained. Compared to other boost methods, an intraoperative treatment has evident advantages in terms of precision (by avoiding a “spatial and/or temporal miss”), cosmetic outcome and patient comfort. Direct visualisation of a tumor bed during surgery guarantees for an accurate dose delivery, which has additionally gained importance in times of primary reconstruction techniques after lumpectomy, since IORT is performed before breast tissue including parts of the tumor bed is mobilized for plastic purposes. As a consequence of direct tissue exposure without distension by hematoma/seroma, IORT allows for small treatment volumes and complete skin sparing, both having a positive effect on late tissue tolerance and, hence, cosmetic appearance. Boost IORT marginally prolongs the surgical procedure, while significantly shortening postoperative radiotherapy. Its combination with external beam radiotherapy to the whole breast (WBI) is currently tested in two multicentric prospective trials: as kV-IORT in the multicentric TARGIT-B (oost) study, and as IOERT in the HIOB trial (3 weeks hypofractionated WBI preceded by IORT electron boost).

TGF-β1 Is Present at High Levels in Wound Fluid from Breast Cancer Patients Immediately Post-Surgery, and Is Not Increased by Intraoperative Radiation Therapy (IORT)

In patients with low-risk breast cancer, intraoperative radiotherapy (IORT) during breast-conserving surgery is a novel and convenient treatment option for delivering a single high dose of irradiation directly to the tumour bed. However, edema and fibrosis can develop after surgery and radiotherapy, which can subsequently impair quality of life. TGF- β is a strong inducer of the extracellular matrix component hyaluronan (HA). TGF-β expression and HA metabolism can be modulated by irradiation experimentally, and are involved in edema and fibrosis. We therefore hypothesized that IORT may regulate these factors.Wound fluid (WF) draining from breast lumpectomy sites was collected and levels of TGF-β1 and HA were determined by ELISA. Proliferation and marker expression was analyzed in primary lymphatic endothelial cells (LECs) treated with recombinant TGF-β or WF. Our results show that IORT does not change TGF-β1 or HA levels in wound fluid draining from breast lumpectomy sites, and does not lead to accumulation of sHA oligosaccharides. Nevertheless, concentrations of TGF-β1 were high in WF from patients regardless of IORT, at concentrations well above those associated with fibrosis and the suppression of LEC identity. Consistently, we found that TGF-β in WF is active and inhibits LEC proliferation. Furthermore, all three TGF-β isoforms inhibited LEC proliferation and suppressed LEC marker expression at pathophysiologically relevant concentrations.

Given that TGF-β contributes to edema and plays a role in the regulation of LEC identity, we suggest that inhibition of TGF-β directly after surgery might prevent the development of side effects such as edema and fibrosis.