Results of chest wall reirradiation using pulsed-dose-rate (PDR) brachytherapy molds for breast cancer local recurrences

Inverse dose protraction effects of low-LET radiation: Evidence and significance

Biological effects of ionizing radiation vary not merely with total dose but also with temporal dose distribution. Sparing dose protraction effects, in which dose protraction reduces effects of radiation have widely been accepted and generally assumed in radiation protection, particularly for stochastic effects (e.g., solid cancer). In contrast, inverse dose protraction effects (IDPEs) in which dose protraction enhances radiation effects have not been well recognized, nor comprehensively reviewed. Here, we review the current knowledge on IDPEs of low linear energy transfer (LET) radiation. To the best of our knowledge, since 1952, 157 biology, epidemiology or clinical papers have reported IDPEs following external or internal low-LET irradiation with photons (X-rays, γ-rays), β-rays, electrons, protons or helium ions. IDPEs of low-LET radiation have been described for biochemical changes in cell-free macromolecules (DNA, proteins or lipids), DNA damage responses in bacteria and yeasts, DNA damage, cytogenetic changes, neoplastic transformation and cell death in mammalian cell cultures of human, rodent or bovine origin, mutagenesis in silkworms, cytogenetic changes, induction of cancer (solid tumors and leukemia) and non-cancer effects (male sterility, cataracts and diseases of the circulatory system), tumor inactivation and survival in non-human mammals (rodents, rabbits, dogs and pigs), and induction of cancer and non-cancer effects (skin changes and diseases of the circulatory system) in humans. In contrast to a growing body of phenomenological evidence for manifestations of IDPEs, there is limited knowledge on mechanistic underpinnings, but proposed mechanisms involve cell cycle-dependent resensitization and low dose hyper-radiosensitivity. These necessitate continued studies for further mechanistic developments and assessment of implications of scientific evidence for radiation protection (e.g., in terms of a dose rate effectiveness factor).

Locoregional recurrence in triple negative breast cancer: past, present, and future

INTRODUCTION

Triple negative breast cancer (TNBC) is a rare but aggressive biological subtype of breast cancer associated with higher locoregional and distant recurrence rates and lower overall survival despite advancements in diagnostic and treatment strategies.

AREAS COVERED

This review explores the evolving landscape of locoregional recurrence (LRR) in TNBC with improved surgical and radiation therapy delivery techniques including salvage breast conserving surgery (SBCS), re-irradiation, and thermo-radiation. We review current retrospective and prospective, albeit limited, clinical data highlighting the optimal management of locoregionally recurrent TNBC. We also discuss tumor genomic profiling and transcriptome analysis and review potential investigational directions.

EXPERT OPINION

Significant progress has been made in the prevention of LRR but rates remain suboptimal, particularly in the TNBC population, and outcomes following LRR are poor. Further prospective studies are needed to identify the most effective and safest systemic therapy regimens and to whom it should be offered. There has been growing interest in the role of molecular markers, genomic signatures, and tumor microenvironment in predicting outcomes and guiding LRR treatment. Transcriptome analyses and biomarker-driven investigations are currently being studied and represent a promising era of development in the management of LRR.

Salvage Perioperative Interstitial High-Dose-Rate Interventional Radiotherapy (Brachytherapy) for Local Recurrences of the Chest Wall Following Mastectomy and Previous External Irradiation

(1) Background: To investigate the technical feasibility, safety, and efficacy of interstitial perioperative high-dose-rate interventional radiotherapy (HDR-IRT, brachytherapy) as a local salvage treatment combined with surgery for local chest wall recurrences following mastectomy and subsequent external beam radiation treatment (EBRT). (2) Methods: A retrospective analysis of 56 patients treated with interstitial HDR-IRT in combination with local surgery of a chest wall recurrence of breast cancer after previous treatment with mastectomy and EBRT from 2008 to 2020. (3) Results: Local recurrence following HDR-IRT was encountered in seven (12.5%) patients. The 1-year local recurrence-free survival (RFS), 3-year RFS, and 5-year RFS were 91%, 82%, and 82%, respectively. The 1-year overall survival (OS), 3-year OS, and 5-year OS was 85.5%, 58%, and 30%, respectively. Acute grade 1-2 radiation dermatitis was observed in 22 (39.3%) patients. Late ≥grade 3 toxicities were encountered in five (8.9%) patients. (4) Conclusions: Salvage perioperative interstitial high-dose-rate interventional radiotherapy (brachytherapy) combined with surgery seems to be an effective interdisciplinary management with acceptable treatment-related toxicity for local recurrences of the chest wall following mastectomy and previous external irradiation.

Radiotherapy and hyperthermia for breast cancer patients at high risk of recurrence

PURPOSE

To evaluate the long-term efficacy of combined radiotherapy (RT) and hyperthermia (HT) in a large mono-institutional cohort of breast cancer (BC) patients affected by recurrent, newly diagnosed non-resectable or high risk resected tumor.

MATERIALS AND METHODS

Records of BC patients treated with RT + HT between 1995 and 2018 were retrospectively analyzed. RT doses of 50-70 Gy concurrent to a twice per week superficial HT were applied. For HT, a temperature between 41 and 42 °C was applied for approximately 1 h. Primary endpoint was local control (LC), secondary endpoints comprised toxicity, overall survival (OS), and progression-free survival (PFS).

RESULTS

A total of 191 patients and 196 RT + HT treatments were analyzed. In 154 cases (78.6%) RT + HT was performed for patients with recurrent BC. Among these, 93 (47.4% of the entire cohort) had received RT prior to RT + HT. Median follow up was 12.7 years. LC at 2, 5, and 10 years was 76.4, 72.8, and 69.5%, respectively. OS at 2, 5, and 10 years was 73.5, 52.3, and 35.5%, respectively. PFS at 2, 5, and 10 years was 55.6, 41, and 33.6%, respectively. Predictive factors for LC were tumor stage, distant metastases, estrogen/progesterone receptor expression, resection status and number of HT fractions. At multivariate analysis tumor stage and receptor expression were significant. No acute or late toxicities higher than grade 3 were observed.

CONCLUSION

Combined RT + HT offers long-term high LC rates with acceptable toxicity for patients with recurrent, newly diagnosed non-resectable or resected BC at high risk of relapse.

Reirradiation for Locoregional Recurrent Breast Cancer

Purpose

Reirradiation poses a distinct therapeutic challenge owing to risks associated with exceeding normal tissue tolerances and possibly more therapeutically resistant disease biology. We report our experience with reirradiation for locoregional recurrent or second primary breast cancer.

Methods and Materials

Between 1999 and 2019, all patients with breast cancer treated with repeat breast/chest wall radiation therapy (RT) at our institution were identified. Adverse events were assessed using the Common Terminology Criteria for Adverse Events v5.0. Fisher exact, Mann-Whitney rank-sum, and unpaired t tests were used for statistical analysis. Freedom from locoregional recurrence and distant metastasis as well as overall survival were calculated using the Kaplan-Meier method.

Results

Seventy-two patients underwent reirradiation. Median prior RT dose, reirradiation dose, and cumulative dose were 60 Gy (interquartile range [IQR], 50-60.4 Gy), 45 Gy (IQR, 40-50 Gy), and 103.54 Gy₂ (IQR, 95.04-109.62 Gy₂), respectively. Median time between RT courses was 73 months (IQR, 29-129 months). Thirty-four patients (47%) had gross residual disease at time of reirradiation. Course intent was described as curative in 44 patients (61%) and palliative in 28 (39%). Fifty-two patients (72%) were treated with photons ± electrons and 20 (28%) with protons. With a median follow-up of 22 months (IQR, 10-43 months), grade 3 adverse events were experienced by 13% of patients (10% acute skin toxicity and 3% late skin necrosis). Time between RT courses and reirradiation fields was significantly associated with the development of grade 3 toxicity at any point. Proton therapy conferred a dosimetric advantage without difference in toxicity. At 2 years, locoregional recurrence-free survival was 74.6% and overall survival was 65.5% among all patients, and 93.1% and 76.8%, respectively, among curative intent patients treated without gross disease. Distant metastasis-free survival was 59.0% among all curative intent patients.

Conclusions

Reirradiation for locoregional recurrent breast cancer is feasible with acceptable rates of toxicity. Disease control and survival are promising among curative intent reirradiation patients without gross disease.

Complex Clinical Decision-Making Process of Re-Irradiation

As patients live longer with their cancer as a result of more effective treatment, recurrences and second malignancies in a previously irradiated field are an increasing challenge. The technical advances that enable high-dose radiation to limited volumes, excluding critical normal tissues, have increased the use of re-irradiation for many tumour sites. Minimising the volume, selecting patients with good performance status, negative metastatic screening and longer disease-free intervals are important principles. Despite this there is a narrow therapeutic window, and careful consideration with open discussion, including the patient, of the probable benefit and the implications of potential toxicities will always be essential. In this overview we evaluate the various radiobiological factors that need to be considered for re-irradiation, tissue recovery and dose tolerances in the setting of re-irradiation and summarise the available literature to guide clinicians in their decision-making for re-irradiation to primary and metastatic site/s of disease.

Proton beam therapy reirradiation for breast cancer: Multi-institutional prospective PCG registry analysis

To investigate adverse events (AEs, CTCAE v4.0) and clinical outcomes for proton beam therapy (PBT) reirradiation (reRT) for breast cancer. From 2011 to 2016, 50 patients received PBT reRT for breast cancer in the prospective Proton Collaborative Group (PCG) registry. Acute AEs occurred within 180 days from start of reRT. Late AEs began or persisted beyond 180 days. Fisher's exact and Mann-Whitney rank-sum tests were utilized. Kaplan-Meier methods were used to estimate overall survival (OS) and local recurrence-free survival (LFRS). Median follow-up was 12.7 months (0-41.8). Median prior RT dose was 60 Gy (10-96.7). Median reRT dose was 55.1 Gy (45.1-76.3). Median cumulative dose was 110.6 Gy (70.6-156.8). Median interval between RT courses was 103.8 months (5.5-430.8). ReRT included regional nodes in 84% (66% internal mammary node [IMN]). Surgery included the following: 44% mastectomy, 22% wide local excision, 6% lumpectomy, 2% reduction mammoplasty, and 26% no surgery. Grade 3 AEs were experienced by 16% of patients (10% acute, 8% late) and were associated with body mass index (BMI) > 30 kg/m² (P = 0.04), bilateral recurrence (P = 0.02), and bilateral reRT (P = 0.004). All grade 3 AEs occurred in patients receiving IMN reRT (P = 0.08). At 1 year, LRFS was 93%, and OS was 97%. Patients with gross disease at time of PBT trended toward worse 1-year LRFS (100% without vs. 84% with, P = 0.06). PBT reRT is well tolerated with favorable local control. BMI > 30, bilateral disease, and IMN reRT were associated with grade 3 AEs. Toxicity was acceptable despite median cumulative dose > 110 Gy.

Therapy of isolated locoregional recurrent carcinoma of the breast

PURPOSE

There is widespread consent that isolated locoregional recurrence (ILRR) in breast cancer should be treated surgically. On searching literature and guidelines most studies include ipsilateral recurrence in breast tissue or on thoracic wall post-mastectomy, recurrence in scar tissue as well as in ipsilateral axillary lymph nodes. Some studies discuss metachronous contralateral breast cancer as ILRR. About 10-35% of women with primary breast cancer suffer from ILRR. The existing data concerning the role of systemic therapy in the treatment of ILRR are insufficient. We investigated the influence of chemotherapy on disease-free- (DFS) and overall-survival (OS).

METHODS

Retrospective analysis of all patients with ILRR and without distant metastasis was done, which were treated at the Department of Gynecology, Obstetrics and Reproductive Medicine, Saarland University between 2005 and 2013. Data collection used patients' database system and was followed via patient questionnaires.

RESULTS

In total, we collected data of 93 patients with locally recurrent breast cancer and observed a 72.6% questionnaire response rate. Average timeline accounted for 99 months between primary diagnosis and local recurrence; average age of patients at diagnosis of local recurrence was 60.6 years. After a median follow-up of 63 months DFS reached 76% with and 73% without chemotherapy, and after 74 months overall survival amounted to 94% and 70%, respectively.

CONCLUSION

Almost all patients with ILRR were operated. Especially patients with hormone receptor-negative recurrent breast cancer seemed to show a benefit having been treated with chemotherapy. Most patients were without recurrence after their particular therapies.

Impact of Technique and Schedule of Reirradiation Plus Hyperthermia on Outcome after Surgery for Patients with Recurrent Breast Cancer

Purpose: Combining reirradiation (reRT) with hyperthermia (HT) has shown to be of high therapeutic value for patients with loco-regionally recurrent breast cancer. The purpose of this study was to compare the long-term therapeutic effect and toxicity of reRT + HT following surgery of loco-regionally recurrent breast cancer using two different reRT regimens. Methods: The reRT regimen of the 78 patients treated in Institute A consisted of 8 × 4 Gy twice a week using mostly abutted photon-electron fields. The 78 patients treated in Institute B received a reRT regimen of 12 × 3 Gy, four times a week with single or multiple electron fields. Superficial hyperthermia was applied once a week in Institute A and twice a week in Institute B. Both institutes started HT treatment within 1 hour after reRT and used the same 434-MHz systems to heat the tumor area to 41–43 °C. Results: The 5-year-infield local control (LC) rates were similar; however, the 5-year-survival rates were 13% lower in Institute A. Most remarkable was the difference in risk with respect to 5-year ≥ grade 3 toxicity, which was more than twice as high in Institute A. Conclusion: The combination of reirradiation and hyperthermia after macroscopically complete excision of loco-regional breast cancer recurrences provides durable local control in patients at risk for locoregional recurrent breast cancer. Treatment is well tolerated with the 12 × 3 Gy schedule with limited-sized electron fields.

Plesiobrachytherapy for chest wall recurrences of breast cancer after mastectomy and radiotherapy for breast cancer

PURPOSE

The purpose of the study was to evaluate the results of high-dose-rate plesiobrachytherapy for local relapse after mastectomy and radiotherapy in terms of both local control and survival.

METHODS

We reviewed retrospectively 43 patients who experienced a chest wall relapse of breast cancer after local excision (22 patients) or not (21 patients). Patients were treated with an individually designed mold with four to six fractions of 3-6 Gy high-dose-rate brachytherapy, two fractions per week. Mean total dose was 24 Gy.

RESULTS

After surgical resection, the 3- and 5-year local control rates were 80% and 73%, respectively. For nonresectable patients, the overall response rate was 86%, and the 3-year infield local control and chest wall local control were 51% and 26%, respectively. The 5-year survival rate was 50.5% for the whole population, 62% after surgery, and 45.4% for irresectable patients. Acute Grade 2 or 3 toxicity occurred in 43% of the patients, resolving in a few days. Two patients had a local necrosis lasting 3 to 7 months. Late toxicity was observed in 5 patients.

CONCLUSIONS

High-dose-rate plesiobrachytherapy is a simple outpatient technique to treat chest wall local relapse of breast cancer. As a reirradiation technique, its tolerance is acceptable. This technique may obtain long-term local control after incomplete surgery; in case of nonresectable disease, a high response rate was observed, which might improve the quality of life of these patients.

Reirradiation for locally recurrent breast cancer

The aim of this study is to review the current status of reirradiation therapy (Re-RT) for locally recurrent breast cancer. The overall outcome of breast/chest wall Re-RT is difficult to assess because of the wide range of different treatments that a patient may have undergone and the patient's individual features. The local control and complete response rates were reported to be 43-96% and 41-71%, respectively. The combination of Re-RT and hyperthermia seems to be related to improved outcomes. Toxicity rates vary between studies, and Re-RT is generally well tolerated. Re-RT may be considered an option for patients with breast cancer relapse after prior irradiation. Further studies are needed to determine the best irradiation volume and treatment modality for patients with locally recurrent disease.

Helical TomoTherapy for locally advanced or recurrent breast cancer

Purpose

We report our experience of using helical tomotherapy (HT) to treat large and irregular shaped loco-regional advanced breast cancer target volumes embracing various organs at risk.

Patients and methods

We retrospectively analyzed 26 patients treated for very large, irregular shaped breast cancers. Patients were treated either with the intent to achieve local control in a primary setting (n = 14) or in a reirradiation setting (n = 12). The recurrence group was heavily pretreated with systemic therapy. Tumors were characterized by wide infiltration of the skin, encompassing mostly a complete hemithorax. The primary group underwent irradiation of supraclavicular, infraclavicular, axillary and parasternal lymphonodal region. Radiotherapy was combined with chemotherapy (n = 11). We assessed the PTV volume and its craniocaudal extension, the dose to the organs at risk, acute toxicity and survival.

Results

Median PTV was 2276 cm³ (1476–6837 cm³) with a median cranio-caudal extension of 28 cm (15–52 cm). The median dose to PTV was 40 Gy (32–60Gy). HT could be carried out in all patients without interruption. The acute toxicities were mild to moderate. The median LRFS and OS after radiotherapy was 21 and 57 months for the primary group versus 10 and 11 months for the recurrence group. Median PFS was 18 months (primary group) and 7 months (recurrence group).

Conclusions

HT is feasible for advanced thorax embracing target volumes with acceptable acute toxicity. Both curative and palliative indications can be considered good indications based on treatment volume and anatomical constellation.

Re-irradiation for locally recurrent refractory breast cancer

Purpose

To report an analysis of treatment outcomes of a cohort of patients re-irradiated for locally recurrent refractory breast cancer (LRRBC)

Patients and Methods

Between 2008 and 2013, 47 women (mean age = 60 years) were re-irradiated for LRRBC. Outcomes were measured using Kaplan-Meier log rank to compare curves and Cox regression for multivariate analysis. Outcomes included overall survival (OS), time to re-treatment, survival without systemic progression, and survival without local recurrence.

Results

Fifty-six instances of re-irradiation were completed and analyzed. The mean cumulative 2 Gy equivalent dose (EQD2) to the whole breast and tumour cavity (α/β = 3) was 99.8 Gy and 109.1 Gy, respectively. Most patients initially had significant symptoms before RT due to local recurrence. The median time to re-treatment and to systemic failure was 41 and 50 months, respectively. Median follow-up for OS was 17 months and OS was 0.73 (SE = 0.07) at 1 year and 0.67 (SE = 0.07) at 2 years. Local control was 0.62 (SE = 0.07) and 0.5 (0.08) at 1 and 2 years, respectively. Acute radiation dermatitis was G1-2, G3 and G4 in 45, 4 and 1 cases, respectively. One patient presented with necrosis. The most common long term toxicity was G3 fibrosis (n = 4) and telangiectatic changes (n = 3). Multivariable analysis indicated that skin involvement (Hazard Ratio = 6.6 (1.4-31), p = 0.016) and time to local recurrence <2yr (HR 3.1 (1.04-9.7) p = 0.042) predicted local recurrence.

Conclusion

High dose re-irradiation is feasible for locally RRBC. This approach can have a significant benefit in this very high-risk group.

DEGRO practical guidelines for radiotherapy of breast cancer VI: therapy of locoregional breast cancer recurrences

Objective

To update the practical guidelines for radiotherapy of patients with locoregional breast cancer recurrences based on the current German interdisciplinary S3 guidelines 2012.

Methods

A comprehensive survey of the literature using the search phrases “locoregional breast cancer recurrence”, “chest wall recurrence”, “local recurrence”, “regional recurrence”, and “breast cancer” was performed, using the limits “clinical trials”, “randomized trials”, “meta-analysis”, “systematic review”, and “guidelines”.

Conclusions

Patients with isolated in-breast or regional breast cancer recurrences should be treated with curative intent. Mastectomy is the standard of care for patients with ipsilateral breast tumor recurrence. In a subset of patients, a second breast conservation followed by partial breast irradiation (PBI) is an appropriate alternative to mastectomy. If a second breast conservation is performed, additional irradiation should be mandatory. The largest reirradiation experience base exists for multicatheter brachytherapy; however, prospective clinical trials are needed to clearly define selection criteria, long-term local control, and toxicity.

Following primary mastectomy, patients with resectable locoregional breast cancer recurrences should receive multimodality therapy including systemic therapy, surgery, and radiation +/− hyperthermia. This approach results in high local control rates and long-term survival is achieved in a subset of patients. In radiation-naive patients with unresectable locoregional recurrences, radiation therapy is mandatory. In previously irradiated patients with a high risk of a second local recurrence after surgical resection or in patients with unresectable recurrences, reirradiation should be strongly considered. Indication and dose concepts depend on the time interval to first radiotherapy, presence of late radiation effects, and concurrent or sequential systemic treatment. Combination with hyperthermia can further improve tumor control.

In patients with isolated axillary or supraclavicular recurrence, durable disease control is best achieved with multimodality therapy including surgery and radiotherapy. Radiation therapy significantly improves local control and should be applied whenever feasible.

Current Treatment of Isolated Locoregional Breast Cancer Recurrences

Patients with isolated locoregional breast cancer recurrences should be treated with curative intent. Mastectomy is regarded as the standard of care for patients with ipsilateral breast tumor recurrence. In a selected group of patients, partial breast irradiation after second breast-conserving surgery is a viable alternative to mastectomy. If a second breast conservation is performed, additional irradiation should be mandatory, especially in patients who had not been irradiated previously. In case of re-irradiation, the largest experience exists for multi-catheter brachytherapy. Prospective clinical trials are needed to clearly define selection criteria, long-term local control, and toxicity. In patients with resectable locoregional breast cancer recurrences after mastectomy, multi-modal therapy comprising complete resection, radiation therapy in previously unirradiated patients, and systemic therapy results in 5-year disease-free and overall survival rates of 69% and 88%, respectively. In radiation-naive patients with unresectable, isolated locoregional recurrences, radiation therapy is mandatory. In selected patients with previous irradiations and unresectable locoregional recurrences, a second irradiation as part of an individual treatment concept can be applied. The increased risk of severe toxicity should always be weighed up against the potential clinical benefit. A combination therapy with hyperthermia can further improve the treatment results.

A review of the clinical experience in pulsed dose rate brachytherapy

Pulsed dose rate (PDR) brachytherapy is a treatment modality that combines physical advantages of high dose rate (HDR) brachytherapy with the radiobiological advantages of low dose rate brachytherapy. The aim of this review was to describe the effective clinical use of PDR brachytherapy worldwide in different tumour locations. We found 66 articles reporting on clinical PDR brachytherapy including the treatment procedure and outcome. Moreover, PDR brachytherapy has been applied in almost all tumour sites for which brachytherapy is indicated and with good local control and low toxicity. The main advantage of PDR is, because of the small pulse sizes used, the ability to spare normal tissue. In certain cases, HDR resembles PDR brachytherapy by the use of multifractionated low-fraction dose.

Optimising treatment distance and treatment area for HDR surface mould brachytherapy

The purpose of this study was to quantify the effect of treatment area and treatment distance on dose distributions for geometrically optimised surface mould plans in order to provide guidance in choosing treatment parameters and constructing moulds for individual patients. Geometrically optimised plans were generated with a typical brachytherapy planning system and measurements were taken with radiochromic film over depths of 5-32 mm with an (192)Ir high dose rate source. Films were calibrated with a cylindrical geometry technique utilising the (192)Ir source and readout was performed with a flatbed scanner. The rate of dose fall-off about the prescription plane, as well as the magnitude and extent of local dose maxima superficial to the prescription plane, increased with decreasing treatment areas when inter-catheter spacing and treatment distance were kept constant. The dose fall-off was highly dependent on treatment distance, with a 16 % reduction in dose 4 mm superficial to the treatment depth occurring when the distance was increased from 10 to 20 mm while maintaining a 10 mm inter-catheter spacing. The table generated using the measured planar geometry data, can be used as an initial guide for mould construction and planning. The properties of high dose regions near to the catheter plane are highly dependent on the treatment area, which must be considered when normal tissue dose tolerances are a concern. Treatment distance is a key variable influencing the overall dose distribution and should be adjusted as a function of the desired tumour to skin dose ratio, controlled by mould thickness.

Durable palliation of breast cancer chest wall recurrence with radiation therapy, hyperthermia, and chemotherapy

BACKGROUND AND PURPOSE

Chest wall recurrences of breast cancer are a therapeutic challenge and durable local control is difficult to achieve. Our objective was to determine the local progression free survival (LPFS) and toxicity of thermochemoradiotherapy (ThChRT) for chest wall recurrence.

METHODS

Twenty-seven patients received ThChRT for chest wall failure from 2/1995 to 6/2007 and make up this retrospective series. All received concurrent superficial hyperthermia twice weekly (median 8 sessions), chemotherapy (capecitabine in 21, vinorelbine in 2, and paclitaxel in 4), and radiation (median 45 Gy). Patients were followed up every 1.5-3 months and responses were graded with RECIST criteria and toxicities with the NCI CTC v4.0.

RESULTS

Twenty-three (85%) patients were previously irradiated (median 60.4 Gy) and 22 (81%) patients received prior chemotherapy. Median follow-up was 11 months. Complete response (CR) was achieved in 16/20 (80%) of patients with follow-up data, and 1 year LPFS was 76%. Overall survival was 23 months for patients with CR, and 5.4 months in patients achieving a partial response (PR) (p=0.01). Twenty-two patients experienced acute grade 1/2 treatment related toxicities, primarily moist desquamation. Two patients experienced 3rd degree burns; all resolved with conservative measures.

CONCLUSIONS

ThChRT offers durable palliation and prolonged LPFS with tolerable acute toxicity, especially if CR is achieved.

Pulsed dose rate brachytherapy - is it the right way?

Pulsed dose rate (PDR-BT) treatment is a brachytherapy modality that combines physical advantages of high-dose-rate (HDR-BT) technology (isodose optimization, radiation safety) with the radiobiological advantages of low-dose-rate (LDR-BT) brachytherapy. Pulsed brachytherapy consists of using stronger radiation source than for LDR-BT and producing series of short exposures of 10 to 30 minutes in every hour to approximately the same total dose in the same overall time as with the LDR-BT. Modern afterloading equipment offers certain advantages over interstitial or intracavitary insertion of separate needles, tubes, seeds or wires. Isodose volumes in tissues can be created flexibly by a combination of careful placement of the catheter and the adjustment of the dwell times of the computerized stepping source. Automatic removal of the radiation sources into a shielded safe eliminates radiation exposures to staff and visitors. Radiation exposure is also eliminated to the staff who formerly loaded and unloaded multiplicity of radioactive sources into the catheters, ovoids, tubes etc. This review based on summarized clinical investigations, analyses the feasibility and the background to introduce this brachytherapy technique and chosen clinical applications of PDR-BT.

Thermal characteristics of thermobrachytherapy surface applicators for treating chest wall recurrence

The aim of this study was to investigate temperature and thermal dose distributions of thermobrachytherapy surface applicators (TBSAs) developed for concurrent or sequential high dose rate (HDR) brachytherapy and microwave hyperthermia treatment of chest wall recurrence and other superficial diseases. A steady-state thermodynamics model coupled with the fluid dynamics of a water bolus and electromagnetic radiation of the hyperthermia applicator is used to characterize the temperature distributions achievable with TBSAs in an elliptical phantom model of the human torso. Power deposited by 915 MHz conformal microwave array (CMA) applicators is used to assess the specific absorption rate (SAR) distributions of rectangular (500 cm(2)) and L-shaped (875 cm(2)) TBSAs. The SAR distribution in tissue and fluid flow distribution inside the dual-input dual-output (DIDO) water bolus are coupled to solve the steady-state temperature and thermal dose distributions of the rectangular TBSA (R-TBSA) for superficial tumor targets extending 10-15 mm beneath the skin surface. Thermal simulations are carried out for a range of bolus inlet temperature (T(b) = 38-43 degrees C), water flow rate (Q(b) = 2-4 L min(-1)) and tumor blood perfusion (omega(b) = 2-5 kg m(-3) s(-1)) to characterize their influence on thermal dosimetry. Steady-state SAR patterns of the R- and L-TBSA demonstrate the ability to produce conformal and localized power deposition inside the tumor target sparing surrounding normal tissues and nearby critical organs. Acceptably low variation in tissue surface cooling and surface temperature homogeneity was observed for the new DIDO bolus at a 2 L min(-1) water flow rate. Temperature depth profiles and thermal dose volume histograms indicate bolus inlet temperature (T(b)) to be the most influential factor on thermal dosimetry. A 42 degrees C water bolus was observed to be the optimal choice for superficial tumors extending 10-15 mm from the surface even under significant blood perfusion. Lower bolus temperature may be chosen to reduce the thermal enhancement ratio (TER) in the most sensitive skin where maximum radiation dose is delivered and to extend the thermal enhancement of radiation dose deeper. This computational study indicates that well-localized elevation of tumor target temperature to 40-44 degrees C can be accomplished by large surface-conforming TBSAs using appropriate selection of coupling bolus temperature.

Differential effects of CLDR and PDR brachytherapy on cell cycle progression in a syngeneic rat prostate tumour model

PURPOSE

The study consisted of two treatment arms comparing the effects of CLDR (continuous low dose rate) and PDR (pulsed dose rate) brachytherapy on cell cycle progression in a radioresistant rat prostate tumour model.

MATERIALS AND METHODS

Interstitial PDR and CLDR brachytherapy (both 192-Ir, 0.75 Gy/h) were administered to Dunning prostate R3327-AT1 carcinomas transplanted subcutaneously into the thigh of Copenhagen rats. Increasing doses of up to 20 as well as up to 40 Gy were applied. Cell cycle distributions of the aneuploid tumour cell subpopulations were determined at 4 h (3 Gy), 24 h (18 Gy), 48 h (20 and 36 Gy), as well as during the subsequent redistribution period (20 and 40 Gy) at 72, 96, and 120 h. Tumours either implemented with an empty tubing system (n=5) or under undisturbed growth (n=5) served as controls. Three animals were irradiated per time point and exposure condition. At least two flow cytometrical analyses were carried out per animal.

RESULTS

The aneuploid cells possessed a constant DNA-Index of 1.9+/-0.06. In contrast to sham-treated controls, the aneuploid cell fraction with G2/M DNA content was significantly increased (p<0.05) after initiation of both, CLDR and PDR brachytherapy. However, CLDR resulted in an earlier accumulation of tumour cells in G2/M (24 h: 28% CLDR vs. 19% PDR, p<0.05) with a concomitant reduction of cells in G1, whereas PDR yielded delayed, but then more pronounced cell cycle changes, particularly expressed during the redistribution period after both 20 and 40 Gy.

CONCLUSION

CLDR and PDR brachytherapy showed differential effects on cell cycle progression. The induction of a significantly earlier but also less persistent G2/M cell cycle arrest after CLDR compared to PDR brachytherapy implies that a substantially higher fraction of tumour cells are irradiated in G2/M after CLDR.

Reirradiation of recurrent breast cancer with and without concurrent chemotherapy

Background

Treatment options for loco-regional recurrent breast cancer after previous irradiation are limited. The efficacy of chemotherapy might be hampered because of impaired tissue perfusion in preirradiated tissue. Thus, mastectomy or local excision and reconstructive surgery are the preferred treatments. However, in recent years evidence accumulates that a second breast conserving approach with reirradiation as part of the treatment might be feasible and safe and, furthermore, reirradiation might be an option for palliation. Here we report on the experience of a single community centre in reirradiation of recurrent breast cancer.

Methods

The report is based on 29 patients treated with reirradiation. All data were prospectively collected. The median age was 63 years (range 35 to 82 yrs). The interval between initial diagnosis and diagnosis before start of reirradiation was 11.6 months to 295.5 months. The mean total dose (initial dose and reirradiation dose) was 106.2 Gy (range 80.4 to 126 Gy) and the mean BED_{3 Gy} 168,5 Gy (range 130,6 to 201,6). The mean interval between initial radiotherapy and reirradiation was 92.9 months (range 8.7 to 290.1). Inoperable or incompletely resected patients were offered concurrent chemotherapy with either 5-FU or capecitabine. All patients received 3D-conformal radiotherapy with 1.6 to 2.5 Gy/fraction five times weekly. The treatment volume comprised all visible lesions or lesions detectable on CT/MRI/FDG-PET/CT or the tumour bed or recurrent tumour.

Results

The local progression-free survival of all patients at one and two years was 81% and 63%. Patients who had no surgery of the recurrence (16/29) had local progression-free survival at one and two years of 72% and 25% with a median progression-free survival time of 17 months. Partial remission and good symptom relief was achieved in 56% (9/16) or complete response of symptoms and/or tumour in 44% (7/16). Patients who had no distant metastases and had at least an R1-resection had a local progression-free survival of 90% after 2 years. The disease-free survival after 2 years was 43% and the median disease-free survival time was 24 months. In four patients a second breast conserving operation was performed and the cosmetic results in all four patients are good to excellent. Acute side effects were mild to moderate with no grade 3 or 4 toxicity. Accordingly, no grade 3 or 4 late effects were observed so far. No grade 3 or 4 plexopathy was observed.

Conclusion

In this heterogeneous group of patients reirradiation of locoregional recurrences of breast cancer showed low to moderate acute toxicity. In our experience, local control rates are high and palliation is good.

Pulsed dose rate brachytherapy

Pulsed dose rate (PDR) is a new modality for dose delivery in brachytherapy. It uses modern afterloading technology (miniaturized source, cable driven, software controlled), with source activities in the range of 1 Ci, which is actually one tenth of the normal activity used for high dose rate (HDR) brachytherapy. Modern technology allows dose optimization, and source strength in the above-mentioned range creates a new dose rate condition. For small fractions (pulses) with short interpulse intervals, PDR mimics the radiobiology of high dose rate brachytherapy, whereas for bigger doses per fraction, dose adjustments are needed to compensate for the loss of therapeutic ratio. Clinical series showed good figures for local control and toxicity. Almost every clinical site has been reported to have been treated with PDR, with some thousand of patients having been reported. Technical difficulties in some body sites can be overcome by slightly modifying the implant technique. PDR brachytherapy is an ideal environment for the development of new dose fractionation schedules. It creates unique conditions in which to operate. Knowledge of tissue repair kinetics is extremely important for adequate selection of dose per pulse and interpulse interval. Therapeutic ratio can be improved by adjusting interpulse intervals to the repair half-times for normal tissues. On the other hand, superfractionated schedules with low dose per pulse can be explored in conditions of tumor hypoxia, thanks to the predicted hypersensitivity at low dose per fraction. The use of chemical agents (nicotinamide and others) in concomitance with this superfractionated schedules is foreseen in controlled clinical trials. In conclusion, PDR brachytherapy can be considered a new paradigm for dose delivery. It is safe and reliable, can be used in the setting of image-guided radiation therapy, and exploit the differential effect of ionizing radiations by a thorough knowledge of tissue kinetics for an improved therapeutic ratio.

Reirradiation after radical radiation therapy: a survey of patterns of practice among Canadian radiation oncologists

PURPOSE

The objective of this study was to survey the use of reirradiation (Re-RT) for in-field failures after previous radical radiation treatment (RT) among Canadian radiation oncologists (ROs).

METHODS AND MATERIALS

An electronic survey was sent to 271 ROs in Canada. The completed surveys were received electronically via e-mail and the data were analyzed using SAS 9.1.3 software.

RESULTS

A total of 183 ROs (67.5%) completed and returned the survey. The majority of the respondents were involved in the practice of either breast (48%) or genitourinary (43%) tumor sites. A total of 49% of the participants were interested in using Re-RT for the management of in-field recurrences. The goals of the therapy would be improvement of quality of life (99%), locoregional control (80%), or cure (32%). Most of the physicians believed that patients should have a minimum Karnofsky performance status of 50 or Eastern Cooperative Oncology Group performance status of 3, a minimum life expectancy of 3 months, and a minimum interval from initial treatment of 3 months if Re-RT were to be given with curative intent.

CONCLUSIONS

This survey showed that a wide variation existed among ROs in their approach to Re-RT. Newer technologies in RT planning and delivery would be employed to facilitate normal tissue avoidance. The results of this study suggested that a consensus meeting was needed to establish guidelines for the practice and prospective evaluation of Re-RT.

Pulsed reduced dose-rate radiotherapy: a novel locoregional retreatment strategy for breast cancer recurrence in the previously irradiated chest wall, axilla, or supraclavicular region

PURPOSE

Reirradiation of breast cancer locoregional recurrence (LRR) in the setting of prior post-mastectomy radiation poses a significant clinical challenge due to the high risk for severe toxicity. In an attempt to reduce these toxicities, we have developed pulsed reduced dose-rate radiotherapy (PRDR), a reirradiation technique in which a series of 0.2 Gy pulses separated by 3-min time intervals is delivered, creating an apparent dose rate of 0.0667 Gy/min. Here we describe our early experience with PRDR.

PATIENTS AND METHODS

We reirradiated 17 patients with LRR breast cancer to the chest wall, axilla, or supraclavicular region using PRDR. The median prior radiation dose was 60 Gy. We delivered a median PRDR dose of 54 Gy (range 40-66 Gy) in 1.8-2.0 Gy per fraction. Eight patients received concomitant low dose capecitabine for radiosensitization. The median treatment volume was 2,084 cm(3) (range 843-7,881 cm(3)).

RESULTS

At a median follow-up of 18 months (range 4-75 months) only 2 patients have had tumor failure in the treatment region. Estimated 2-year local control rate is 92%. Treatment was well tolerated with 4 patients experiencing grade 3 acute skin toxicity. Despite a median cumulative dose of 110 Gy (range 80-236 Gy), there has been only one grade 3 and one grade 4 late toxicity.

CONCLUSIONS

With a median follow-up of 18 months, PRDR appears to be an effective method to reirradiate large volumes of previously irradiated tissue in selected patients with locoregional chest wall, axilla, and supraclavicular recurrences.

Daytime pulsed dose rate brachytherapy as a new treatment option for previously irradiated patients with recurrent oesophageal cancer

The aim of this study was to evaluate the feasibility, effects, and toxicity of pulsed dose rate (PDR) brachytherapy for re-irradiation of oesophageal carcinoma. A total of 16 patients (median age 67 years) with inoperable recurrences from oesophageal cancer after primary radio-(chemo)-therapy (median 50 Gy) were re-irradiated using PDR brachytherapy ((192)Ir, 37 GBq). Treatment was carried out on an outpatient basis applying a weekly 5 Gy daytime schedule (0.5 Gy pulse(-1) h(-1), total dose 15-20 Gy). The dose was prescribed 10 mm from the mid-dwell position and encompassed the clipped tumour extension with 2 cm margins. The use of clips for delineation of tumour extent and catheter movement during irradiations was evaluated. All 61 PDR treatments were applied safely. The median catheter movement was 5 mm, range 2-12 mm. After a median follow-up of 8 months, three patients had a complete and five a partial remission. Body weight increased in 5 of 16 (31%) and was stable in 4 of 16 (25%) patients, respectively. The median grade 2 (RTOG/EORTC) dysphagia-free survival was 17 months. Seven patients experienced grade 1, five grade 2, and one grade 3 late toxicity. Three patients with uncontrolled locoregional disease showed grade 4 complications (oesophago-tracheal fistulae (n=2), fatal arterial bleeding (n=1). Daytime PDR brachytherapy proved to be feasible and provided effective palliation. Toxicity remains a major problem. Thus, total dose should be restricted to <15 Gy in this palliative situation.

CT computer-optimized high-dose-rate brachytherapy with surface applicator technique for scar boost radiation after breast reconstruction surgery

PURPOSE

Immediate breast reconstruction has become increasingly prevalent after mastectomy for breast cancer. Postoperative scar boost radiation for the reconstructed breast presents many planning challenges due to the shape, size, and curvature of the scar. High-dose-rate (HDR) surface applicator brachytherapy is a novel and effective method of delivering scar boost radiation. Two cases, one with a saline implant and one with a transverse rectus abdominis musculocutaneous flap reconstruction, illustrate the method and advantages of HDR optimization of surface applicators.

METHODS AND MATERIALS

For 2 patients a mold of the breast was made with Aquaplast sheets. A reproducible system was used for arm positioning. Skin fiducials, including tattoos from external beam planning, were matched to fiducials on the mold. HDR catheters were sited on the mold at 1cm intervals, with the central catheter situated along the scar. Topographically, both scars demonstrated extreme curvature in both craniocaudal and mediolateral directions. A CT computer-optimized HDR plan was developed, with the reference dose prescribed at the skin surface. The dosimetry was compared to single-field and matched-field electron plans.

RESULTS

This surface applicator technique provided a uniform skin dose of 100% to the entire clinical target volume (CTV) without hot spots in both patients. The patient position and surface applicator setup were consistently reproducible. The patients tolerated the treatment well with minimal skin erythema. In the single-field electron plan, skin dose was decreased to 50% at the periphery of the scar. Matching fields addressed this depth dose decrement, but resulted in large localized hot spots of more than 200% centrally in each field.

CONCLUSION

CT computer-optimized HDR surface applicator brachytherapy provided a reproducible homogeneous method of treating highly curved scars on the reconstructed breast. Electron beam treatment would result in longer and more complex treatments yet still provide a less homogeneous dose than this surface applicator technique.

Ré-irradiation pariétale après mastectomie de rattrapage pour récidive d’un cancer du sein après traitement conservateur : étude rétrospective sur 20 patientes (Nancy : 1988–2001)

PURPOSE

To retrospectively assess the efficacy of post-mastectomy re-irradiation for local relapse of breast cancer.

PATIENTS AND METHODS

Twenty patients, initially treated by conservative surgery and radiotherapy (50 Gy in 25 fractions over 5 weeks) were treated from 1998 to 2001 for a local relapse by salvage mastectomy and re-irradiation (either electron or photon beams). Mean age was 53 years (31-71). Reasons for re-irradiation were that the local relapses were inflammatory (4 pts), multifocal (5 pts), cutaneous (5 pts), involved the nipple (3 pts) or because the surgical margins (either muscle or skin) were involved (3 pts). The median dose of re-irradiation was 45 Gy (33-65) in 15 fractions over 33 days. Mean follow-up was 48 months (5-97).

RESULTS

Fifteen patients remained free of a second local recurrence and 10 were still alive, without metastasis. Neither the dose of re-irradiation nor the irradiated surfaces were prognostic factors of local control (P = 0.877 and P = 0.424). Five patients developed radiation-induced pneumonitis without functional respiratory impairment. The incidence of pneumonitis seemed to be related to the biological dose of re-irradiation (P = 0.037). Other late complications occurred such as pigmentation changes (12 pts), telangiectasia (8 pts), chondritis (2 pts), parietal fibrosis (7 pts), rib fractures (4 pts), severe pain (11 pts) and lymphedema (2 pts). The increase in biological equivalent dose was highly statistically linked with the occurrence of disabling pain (P = 0.0123).

CONCLUSION

Parietal re-irradiation achieves good and lasting local control with an acceptable rate of acute complications but with a risk of disabling late sequelae such as severe pain.