Initial Clinical Experience With the Strut-Adjusted Volume Implant (SAVI) Breast Brachytherapy Device for Accelerated Partial-Breast Irradiation (APBI): First 100 Patients With More Than 1 Year of Follow-Up

Radiation-associated breast angiosarcoma after strut-adjusted volume implant brachytherapy

Angiosarcoma is a rare malignancy that may classically occur in the post-treatment breast. Radiation and post-treatment edema have been identified in the literature as causative risk factors. Modern treatment innovations have provided patients with more targeted radiation therapy and more conservative surgical options, which may individually limit exposure to these risk factors. Advanced treatment options are also able to provide superior cosmetic outcomes that can positively impact patient quality of life. Despite the ability for modern treatment options to mitigate post-treatment morbidities, there is still long-term risk to the patient of developing treatment-related pathologies, such as breast angiosarcoma. Here we present a patient who underwent lumpectomy and received targeted brachytherapy through a strut-adjusted volume implant device to her lumpectomy site. Her initial post-treatment course was mildly complicated by localized breast lymphedema, which resolved and left the patient with favorable cosmetic results. She developed treatment-associated breast angiosarcoma after initial breast conservation therapy was completed approximately 6 and a half years prior. Her presenting physical exam and imaging findings are portrayed with a comprehensive discussion of the commonly described presenting clinical features and imaging findings of breast angiosarcoma. Factors related to radiation treatment planning and use of the strut-adjusted volume implant device are also discussed. Comparisons between primary and secondary breast angiosarcoma are made, and a review of treatment options is given.

Partial Breast Irradiation for Patients With Early-Stage Invasive Breast Cancer or Ductal Carcinoma In Situ: An ASTRO Clinical Practice Guideline

PURPOSE

This guideline provides evidence-based recommendations on appropriate indications and techniques for partial breast irradiation (PBI) for patients with early-stage invasive breast cancer and ductal carcinoma in situ.

METHODS

ASTRO convened a task force to address 4 key questions focused on the appropriate indications and techniques for PBI as an alternative to whole breast irradiation (WBI) to result in similar rates of ipsilateral breast recurrence (IBR) and toxicity outcomes. Also addressed were aspects related to the technical delivery of PBI, including dose-fractionation regimens, target volumes, and treatment parameters for different PBI techniques. The guideline is based on a systematic review provided by the Agency for Healthcare Research and Quality. Recommendations were created using a predefined consensus-building methodology and system for grading evidence quality and recommendation strength.

RESULTS

PBI delivered using 3-dimensional conformal radiation therapy, intensity modulated radiation therapy, multicatheter brachytherapy, and single-entry brachytherapy results in similar IBR as WBI with long-term follow-up. Some patient characteristics and tumor features were underrepresented in the randomized controlled trials, making it difficult to fully define IBR risks for patients with these features. Appropriate dose-fractionation regimens, target volume delineation, and treatment planning parameters for delivery of PBI are outlined. Intraoperative radiation therapy alone is associated with a higher IBR rate compared with WBI. A daily or every-other-day external beam PBI regimen is preferred over twice-daily regimens due to late toxicity concerns.

CONCLUSIONS

Based on published data, the ASTRO task force has proposed recommendations to inform best clinical practices on the use of PBI.

Characterization of Dosimetric Differences in Strut-Adjusted Volume Implant Treatment Plans Calculated With TG-43 Formalism and a Model-Based Dose Calculation Algorithm

PURPOSE

To comprehensively characterize dosimetric differences between calculations with a commercial model-based dose calculation algorithm (MBDCA) and the TG-43 formalism in application to accelerated partial breast irradiation (APBI) with the strut-adjusted volume implant (SAVI) applicator.

METHODS

Dose for 100 patients treated with the SAVI applicator was recalculated with an MBDCA for comparison to dose calculated via TG-43. For every pair of dose calculations, dose-volume histogram (DVH) metrics including V90%, V95%, V100%, V150%, and V200% for the PTV_EVAL were compared. Features were defined for each case including (1) applicator size, (2) ratio between PTV_EVAL contour and 1-cm rind surrounding SAVI applicator, (3) ratio between dwell time in central catheter and total dwell time, and (4) mean computed tomography (CT) number within the lumpectomy cavity. Wilcoxon rank sum tests were performed to test whether treatment plans could be stratified according to feature values into groups with statistically significant dosimetry differences between MBDCA and TG-43.

RESULTS

For all DVH metrics, differences between TG-43 and MBDCA calculations were statistically significant (P < .05). Minimum (maximum) relative percent differences between the MBDCA and TG-43 for V90%, V95%, and V100% were -2.1% (0.1%), -3.1% (-0.1%), and -5.0% (-0.5%), respectively. The median relative percent difference in mean PTV_EVAL dose between the MBDCA and TG-43 was -3.9%, with minimum (maximum) difference of -6.5% (-1.8%). For V90%, V95%, and V100%, plan quality worsened beyond defined thresholds in 26, 23, and 31 cases with no instances of coverage improvement. Features 1, 2, and 4 were shown to be able to stratify treatment plans into groups with statistically significant differences in dosimetry metrics between MBDCA and TG-43.

CONCLUSIONS

Investigated dose metrics for SAVI treatments were found to be systematically lower with MBDCA calculation in comparison to TG-43. Plans could be stratified according to several features by the magnitude of dosimetric differences between these calculations.

Breast brachytherapy

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

Risk Factors for Fat Necrosis After Stereotactic Partial Breast Irradiation for Early-Stage Breast Cancer in a Phase 1 Clinical Trial

PURPOSE

This study reports predictive dosimetric and physiologic factors for fat necrosis after stereotactic-partial breast irradiation (S-PBI).

METHODS AND MATERIALS

Seventy-five patients with ductal carcinoma-in situ or invasive nonlobular epithelial histologies stage 0, I, or II, with tumor size <3 cm were enrolled in a dose-escalation, phase I S-PBI trial between January 2011 and July 2015. Fat necrosis was evaluated clinically at each follow-up. Treatment data were extracted from the Multiplan Treatment Planning System (Cyberknife, Accuray). Univariate and stepwise logistic regression analyses were conducted to identify factors associated with palpable fat necrosis.

RESULTS

With a median follow-up of 61 months (range: 4.3-99.5 months), 11 patients experienced palpable fat necrosis, 5 cases of which were painful. The median time to development of fat necrosis was 12.7 months (range, 3-42 months). On univariate analyses, higher V32.5-47.5 Gy (P < .05) and larger breast volume (P < .01) were predictive of any fat necrosis; higher V35-50 Gy (P < .05), receiving 2 treatments on consecutive days (P = .02), and higher Dmax (P = .01) were predictive of painful fat necrosis. On multivariate analyses, breast volume larger than 1063 cm³ remained a predictive factor for any fat necrosis; receiving 2 treatments on consecutive days and higher V45 Gy were predictive of painful fat necrosis. Breast laterality, planning target volume (PTV), race, body mass index, diabetic status, and tobacco or drug use were not significantly associated with fat necrosis on univariate analysis.

CONCLUSIONS

Early-stage breast cancer patients treated with breast conserving surgery and S-PBI in our study had a fat necrosis rate comparable to other accelerated partial breast irradiation modalities, but S-PBI is less invasive. To reduce risk of painful fat necrosis, we recommend not delivering fractions on consecutive days; limiting V42.5 < 50 cm³, V45 < 20 cm³, V47.5 < 1 cm³, Dmax ≤ 48 Gy and PTV < 100 cm³ when feasible; and counseling patients about the increased risk for fat necrosis when constraints are not met and for those with breast volume >1000 cm³.

Six-Year Results From a Phase I/II Trial for Hypofractionated Accelerated Partial Breast Irradiation Using a 2-Day Dose Schedule

BACKGROUND

To report 6-year outcomes from a phase I/II trial using balloon-based brachytherapy to deliver APBI in 2 days.

METHODS

A total of 45 patients with early-stage breast cancer received adjuvant APBI in 2 days with high-dose rate (HDR) brachytherapy totaling 2800 cGy in 4 fractions (700 cGy BID) using a balloon-based applicator as part of a prospective phase I/II clinical trial. All patients had negative margins and skin spacing ≥8 mm. We evaluated toxicities (CTCAE v3) as well as ipsilateral breast tumor recurrence (IBTR), regional nodal failure (RNF), distant metastasis, disease-free survival, cause-specific survival, and overall survival.

RESULTS

Median age and tumor size were 66 years old (48 to 83) and 0.8 cm (0.2 to 2.3 cm), respectively. Four percent of patients were N1 (n=2) and 73% were estrogen receptor (ER) positive (n=32). Median follow-up was 6.2 years (2.4 to 8.0 y). Nearly all toxicities at 6 years were grade 1 to 2 except 1 instance of grade 3 telangiectasia (2%). Eleven percent (n=5) of patients had chronic asymptomatic fat necrosis whereas asymptomatic seromas were noted on mammogram in 13% of cases (n=6). Cosmesis at last follow-up was good or excellent in 91% of cases (n=40) and fair in 9% (n=4). Two of the previously reported rib fractures healed with conservative measures. There were no IBTR or RNF (6 y IBTR/RNF rate 0%); however, 2 patients experienced distant metastasis (4% at 6 y). The 6-year actuarial disease-free survival, cause-specific survival, and overall survival were 96%, 100%, and 93%, respectively.

CONCLUSIONS

Hypofractionated 2-day APBI using brachytherapy resulted in excellent clinical outcomes with acceptable chronic toxicities.

Evolution of brachytherapy treatment planning to deterministic radiation transport for calculation of cardiac dose

Brachytherapy was among the first methods of radiotherapy and has steadily continued to evolve. Here we present a brief review of the progression of dose calculation methods in brachytherapy to the current state-of-the art computerized methods for heterogeneity correction. We further review the origin and development of the BrachyVision (Varian Medical Systems, Inc., Palo Alto, CA) treatment planning system and evaluate dosimetric results from 12 patients implanted with the strut-assisted volumetric implant (SAVI) applicator (Cianna Medical, Aliso Viejo, CA) for accelerated partial breast irradiation (APBI). Dosimetric results from plans calculated using homogenous and heterogeneous algorithms have been compared to investigate the impact of heterogeneity corrections. Our study showed large percent difference between mean cardiac doses 11.8 ± 6.2% (p = 0.0007) calculated with and without heterogeneity corrections. Our findings are consistent with those of others, indicating an overestimation of the distal dose to organs-at-risk by traditional methods, especially at interfaces between air and tissue.

Efficiency of using the day-of-implant CT for planning of SAVI APBI

PURPOSE

The purpose of the study was to develop an optimized, efficient workflow for using the day-of-implant (DOI) CT for treatment planning of accelerated partial breast irradiation brachytherapy using the strut-adjusted volume implant (SAVI) device.

METHODS AND MATERIALS

For 62 consecutive SAVI patients, a DOI CT was acquired and used for treatment planning. A "verification" CT was acquired 24-72 h after implant and immediately before the first fraction, then registered to the DOI CT. If the DOI CT-based plan was no longer optimal, a replan was performed. An array of metrics describing the geometry of the device and its relative position in the patient from the DOI CTs for these patients was collected. These metrics from the DOI CT were evaluated to determine what features could predict for the need to replan before the first treatment fraction. Logistical regression analysis including χ² tests was used to determine if different factors correlated with replanning.

RESULTS

Twenty-two of 62 patients (35%) required replanning. Only the presence of splayed struts, where splay was toward the skin, and the use of a nine strut ("8-1") SAVI were significantly correlated (p < 0.05) with replanning. Within these individual populations, no additional factors showed a significant statistical correlation for requiring replanning.

CONCLUSIONS

For strut-based accelerated partial breast irradiation brachytherapy, it was feasible to treat with a plan based on the DOI CT for a majority (65%) of patients. Some factors correlate to needing replanning; recognizing these could be used to optimize treatment workflow for certain patients, increasing clinical efficiency while enhancing the quality of patient care.

Updates in the Treatment of Breast Cancer with Radiotherapy

Breast-conserving therapy is one of the most remarkable achievements of modern cancer care. The authors review the evidence supporting the role of adjuvant radiotherapy as the standard of care for breast cancer after breast-conserving surgery, consensus guidelines for margins in invasive cancer disease and ductal carcinoma in situ, the role of partial-breast irradiation and hypofractionated whole-breast irradiation, and the evolving indications for postmastectomy radiation therapy and extent of nodal coverage. Areas of research include specific methods of partial-breast irradiation, interactions between neoadjuvant chemotherapy and radiotherapy, and integration of molecular profiles with the selection of the best treatment modality and timing.

Clinical outcomes, toxicity, and cosmesis in breast cancer patients with close skin spacing treated with accelerated partial breast irradiation (APBI) using multi-lumen/catheter applicators

PURPOSE

Accelerated partial breast irradiation (APBI) using a single-lumen device is associated with better cosmetic outcomes if the spacing between the applicator and skin is > 7 mm. However, there are no reports addressing the late toxicity and clinical outcomes in patients treated with single-entry multi-lumen/catheter applicators who had close skin spacing (7 mm or less). We undertook this study to report clinical outcome, acute and late toxicity as well as cosmesis of early stage breast cancer patients with close skin spacing treated with APBI using multi-lumen or multi-catheter devices.

MATERIAL AND METHODS

This is a retrospective study of all breast cancer patients who had undergone APBI using single-entry multi-lumen/catheter devices in a single institution between 2008 to 2012. The study was limited to those with ≤ 7 mm spacing between the device and skin.

RESULTS

We identified 37 patients and 38 lesions with skin spacing of ≤ 7 mm. Seven lesions (18%) had spacing of ≤ 3 mm. Median follow-up was 47.5 months. There was one case of ipsilateral breast recurrence and one ipsilateral axillary recurrence. Based on RTOG criteria, 22 treated lesions experienced grade 1 and 9 lesions experienced grade 2 toxicity. Twenty-one lesions experienced late grade 1 toxicity. One patient had to undergo mastectomy due to mastitis. Twenty-four treated breasts showed excellent and 11 had good cosmetic outcome. Overall cosmesis trended towards a significant correlation with skin spacing. However, all patients with ≤ 3 mm skin spacing experienced acute and late toxicities.

CONCLUSIONS

Accelerated partial breast irradiation can be safely performed in patients with skin spacing of ≤ 7 mm using single-entry multi-lumen/catheter applicators with excellent cosmetic outcomes and an acceptable toxicity profile. However, skin spacing of ≤ 3 mm is associated with acute and late toxicity and should be avoided if possible.

Feasibility and full-course dosimetry of an intraoperatively placed multichannel brachytherapy catheter for accelerated partial breast irradiation

PURPOSE

Determine feasibility and resultant dosimetry of an intraoperatively placed multichannel intracavitary brachytherapy catheter for accelerated partial breast irradiation (APBI).

METHODS

Patients with breast cancer underwent intraoperative brachytherapy catheter placement based on frozen section analysis with immediate postoperative APBI. The planning target volume evaluation (PTVEval) and organs at risk were contoured on daily pretreatment CT scans for each patient, and the original treatment plan was applied to assess full-course dosimetry.

RESULTS

Of the first 21 patients consented for intraoperative catheter placement, 20 (95%) were able to proceed with treatment as planned. The mean volume of PTVEval receiving 90% of prescription dose (V_90%) and mean percentage of prescription dose to 90% of the PTVEval (D_90%) on initial planning were 96.7 (±1.1%) and 100.2 (±2.1%), respectively. Full-course dose coverage remained excellent with a mean PTVEval V_90% and D_90% of 95.0 (±4.4%) and 100.2 (±9.6%), respectively. Mean full-course maximum dose constraints for chest wall and skin were met by 70% and 95% of patients, respectively. Air accumulation >1 cc during treatment increased the risk of a daily fraction with PTVEval coverage below goal (odds ratio, 9.8; p = 0.05), whereas those with applicators <0.5 cm from the chest wall at planning were at risk of exceeding that organ's maximum dose constraint on a daily fraction (odds ratio, 45; p = 0.02).

CONCLUSIONS

Intraoperative catheter placement and early initiation of APBI based on frozen section pathology is feasible, yields acceptable dosimetry, and is an option for completing breast conserving therapy in less than 10 days.

Lower mean heart dose with deep inspiration breath hold-whole breast irradiation compared with brachytherapy-based accelerated partial breast irradiation for women with left-sided tumors

PURPOSE

For left-sided breast cancer, radiation to the heart is a concern. We present a comparison of mean heart and coronary artery biologically effective dose (BED) between accelerated partial breast irradiation (APBI) and whole breast irradiation with deep inspiration breath-hold technique (DIBH-WBI).

METHODS AND MATERIALS

A total of 100 patients with left-sided, early-stage breast cancer were identified. Fifty underwent single-entry catheter-based APBI and 50 underwent DIBH-WBI. The heart, left anterior descending/interventricular branch, left main, and right coronary artery were delineated. BEDs were calculated from APBI treatment plans (34 Gy in 3.4 Gy twice daily fractions) and for 4 separate plans generated for each DIBH-WBI patient: 50 Gy in 25 fractions (50/25), 50/25 + 10/5 boost, 40/15, and 40/15 + 10/5 boost.

RESULTS

BED to the heart and coronary vessels were statistically significantly higher with APBI than with any of the DIBH-WBI dose/fractionation schedules.

CONCLUSIONS

For women with left-sided early-stage breast cancer, DIBH-WBI resulted in statistically significantly lower mean BED to the heart and coronary vessels compared with APBI. This is likely due to increased physical separation between the heart and tumor bed afforded by the DIBH-WBI technique. Long-term assessment of late effects in these tissues will be required to determine whether these differences are clinically significant.

Prospective analysis of toxicity in patients treated with strut-adjusted volume implant for early-stage breast cancer

PURPOSE

We report the toxicity of patients treated with strut-adjusted volume implant (SAVI) for accelerated partial breast irradiation treated at our institution.

METHODS AND MATERIALS

Patients treated from January 2013 to July 2015 with SAVI planned for 10 b.i.d. fractions for a total dose of 34 Gy were included. Acute and late toxicities were prospectively collected on patients in followup and graded by the Common Terminology Criteria for Adverse Events, version 4.0.

RESULTS

A total of 132 patients were included, with 1 patient having synchronous breast cancer treated in each breast. Median followup was 20.0 months (range, 2.7-37.4 months). The median age at diagnosis was 61 years (range, 41-83 years). Forty-two lesions (32%) were in situ, 88 lesions (66%) were Stage 1, and 3 (2%) lesions were Stage 2. The median planning target volume was 58.2 cc (range, 24.2-109.9 cc), median V150 was 26.3 cc (range, 11.5-47.5 cc), and median V200 was 13.0 cc (range, 6.3-26.1 cc). On a pain scale of 0-10 (10 = worst pain), pain was worst on Day 2 of treatment, with an average score of 0.46. There was one acute skin infection; there were three late skin infections, two of which was Grade 3. Other late toxicities were Grade 1 or 2: hyperpigmentation (44%), telangiectasia (0.8%), seroma (9%), fat necrosis (5%), and fibrosis (12%). Crude local recurrence rate was 4%.

CONCLUSION

SAVI is a safe treatment option for patients who are candidates for accelerated partial breast irradiation. Local control seems to be excellent, but longer followup is needed.

Accelerated partial breast irradiation: advances and controversies

The management of localized breast cancer has changed dramatically over the past three to four decades. Breast-conserving therapy, which involved lumpectomy followed by adjuvant irradiation, is now widely considered the standard of care in women with early-stage breast cancer. Accelerated partial breast irradiation (APBI), which involves focal irradiation of the lumpectomy cavity over a short period of time, has developed over the past two decades as an alternative to whole breast irradiation (WBI). Multiple APBI modalities have been developed including brachytherapy, external beam irradiation, and intraoperative irradiation. These new techniques have provided early-stage breast cancer patients with shorter treatment duration and more focused irradiation, delivering very high biological doses to the region at a high risk of failures over a much shorter treatment course as compared with conventional radiotherapy. However, the advantages of APBI over conventional radiotherapy are controversial, including a higher risk of complications reported in retrospective literature and shorter follow-up duration in the intraoperative APBI trials. Nevertheless, APBI presents a valuable alternative to WBI for a selected population of women with early-stage breast cancer.

Accelerated partial breast irradiation utilizing brachytherapy: patient selection and workflow

Accelerated partial breast irradiation (APBI) represents an evolving technique that is a standard of care option in appropriately selected woman following breast conserving surgery. While multiple techniques now exist to deliver APBI, interstitial brachytherapy represents the technique used in several randomized trials (National Institute of Oncology, GEC-ESTRO). More recently, many centers have adopted applicator-based brachytherapy to deliver APBI due to the technical complexities of interstitial brachytherapy. The purpose of this article is to review methods to evaluate and select patients for APBI, as well as to define potential workflow mechanisms that allow for the safe and effective delivery of APBI. Multiple consensus statements have been developed to guide clinicians on determining appropriate candidates for APBI. However, recent studies have demonstrated that these guidelines fail to stratify patients according to the risk of local recurrence, and updated guidelines are expected in the years to come. Critical elements of workflow to ensure safe and effective delivery of APBI include a multidisciplinary approach and evaluation, optimization of target coverage and adherence to normal tissue guideline constraints, and proper quality assurance methods.

Accelerated partial breast irradiation with brachytherapy: patient selection and technique considerations

Accelerated partial breast irradiation (APBI) through breast brachytherapy is a relatively recent development in breast radiotherapy that has gained international favor because of its reduction in treatment duration and normal tissue irradiation while maintaining favorable cancer-specific and cosmetic outcomes. Despite the fact that several large national trials have not reported final results yet, many providers are currently offering APBI to select patients and APBI is listed as a treatment option for selecting patients in the National Comprehensive Cancer Network guidelines. Multiple consensus guidelines exist in selecting patients for APBI, some with conflicting recommendations. In this review, the existing patient selection guidelines are reported, compared, and critiqued, grouping them in helpful subcategories. Unique patient and technical selection factors for APBI with brachytherapy are explored.

Review of advanced catheter technologies in radiation oncology brachytherapy procedures

The development of new catheter and applicator technologies in recent years has significantly improved treatment accuracy, efficiency, and outcomes in brachytherapy. In this paper, we review these advances, focusing on the performance of catheter imaging and reconstruction techniques in brachytherapy procedures using magnetic resonance images and electromagnetic tracking. The accuracy of catheter reconstruction, imaging artifacts, and other notable properties of plastic and titanium applicators in gynecologic treatments are reviewed. The accuracy, noise performance, and limitations of electromagnetic tracking for catheter reconstruction are discussed. Several newly developed applicators for accelerated partial breast irradiation and gynecologic treatments are also reviewed. New hypofractionated high dose rate treatment schemes in prostate cancer and accelerated partial breast irradiation are presented.

The incidence of fat necrosis in balloon-based breast brachytherapy

Purpose

To investigate the incidence of and potential risk factors for fat necrosis in high dose-rate (HDR) balloon-based breast brachytherapy (BBB).

Material and methods

Fifty-four patients were treated postoperatively with HDR-BBB between May 2007 and December 2010. Median age was 71 years (range: 50-88 years). Median tumor size was 1 cm (range: 0.1-2.7 cm). Forty-four had invasive histology; 43% were grade 1, 24% grade 2, and 15% grade 3. The median margin size was 0.7 cm (range: 0.1-1.5 cm).

Results

With a median follow-up of 2.9 years (range: 0.5-5.2 years), local control was 98% with one in-breast failure, and overall survival was 89%. Fifty percent of patients experienced fat necrosis. Seven patients were symptomatic, with the remainder detected by mammography alone. Two patients required surgical resection with pathology confirming fat necrosis; 1 required i.v. steroids. At 1, 3, and 5 years following treatment, estimated cumulative incidences of fat necrosis were 7.5%, 52.7%, and 60.6%. Breast laterality, location, tumor size, histology, margin size, balloon volume, skin distance, skin dose, and number of dwell positions were not significantly associated with fat necrosis on univariate analysis.

Conclusions

In this retrospective review of HDR-BBB, we found a 50% incidence of both asymptomatic and symptomatic fat necrosis. Only three patients, however, required intervention. None of the risk factors considered were significantly associated with fat necrosis. Further studies evaluating factors associated with fat necrosis for patients undergoing HDR-BBB are necessary to appropriately assess the risks associated with treatment.

Balloon brachytherapy for breast cancer prove that it works? Or, prove that it doesn't?

Balloon breast brachytherapy is a catheter-based technique to deliver high local concentration of radiation following breast-sparing surgery. Although this technique is logically appealing--providing more directed radiation to sites at high risk of local failure--there remains little empirical support that this intervention is non-inferior to external beam radiotherapy, a well-established standard. Additionally, observational studies suggest that balloon brachytherapy is associated with high rates of local complications, and higher rates of subsequent mastectomy, a marker of local failure. Here, I explore regulatory and clinical considerations that lead to the widespread adoption of breast brachytherapy. I argue that the therapy spread before its efficacy was confirmed. Breast brachytherapy illustrates ongoing complexities in the approval of novel devices.

Decline of cosmetic outcomes following accelerated partial breast irradiation using intensity modulated radiation therapy: results of a single-institution prospective clinical trial

PURPOSE

To report the final cosmetic results from a single-arm prospective clinical trial evaluating accelerated partial breast irradiation (APBI) using intensity modulated radiation therapy (IMRT) with active-breathing control (ABC).

METHODS AND MATERIALS

Women older than 40 with breast cancer stages 0-I who received breast-conserving surgery were enrolled in an institutional review board-approved prospective study evaluating APBI using IMRT administered with deep inspiration breath-hold. Patients received 38.5 Gy in 3.85-Gy fractions given twice daily over 5 consecutive days. The planning target volume was defined as the lumpectomy cavity with a 1.5-cm margin. Cosmesis was scored on a 4-category scale by the treating physician. Toxicity was scored according to National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE version 3.0). We report the cosmetic and toxicity results at a median follow-up of 5 years.

RESULTS

A total of 34 patients were enrolled. Two patients were excluded because of fair baseline cosmesis. The trial was terminated early because fair/poor cosmesis developed in 7 of 32 women at a median follow-up of 2.5 years. At a median follow-up of 5 years, further decline in the cosmetic outcome was observed in 5 women. Cosmesis at the time of last assessment was 43.3% excellent, 30% good, 20% fair, and 6.7% poor. Fibrosis according to CTCAE at last assessment was 3.3% grade 2 toxicity and 0% grade 3 toxicity. There was no correlation of CTCAE grade 2 or greater fibrosis with cosmesis. The 5-year rate of local control was 97% for all 34 patients initially enrolled.

CONCLUSIONS

In this prospective trial with 5-year median follow-up, we observed an excellent rate of tumor control using IMRT-planned APBI. Cosmetic outcomes, however, continued to decline, with 26.7% of women having a fair to poor cosmetic result. These results underscore the need for continued cosmetic assessment for patients treated with APBI by technique.

Progress and controversies: radiation therapy for invasive breast cancer

Radiation therapy is a critical component of the multidisciplinary management of invasive breast cancer. In appropriately selected patients, radiation not only improves local control, sparing patients the morbidity and distress of local recurrence, but it also improves survival by preventing seeding and reseeding of distant metastases from persistent reservoirs of locoregional disease. In recent years, considerable progress has been made toward improving our ability to select patients most likely to benefit from radiotherapy and to administer treatment in ways that maximize clinical benefit while minimizing toxicity and burden. This article reviews the role of radiation therapy in invasive breast cancer management, both after breast-conserving surgery and after mastectomy. It focuses particularly on emerging evidence that helps to define the clinical situations in which radiotherapy is indicated, the appropriate targets of treatment, and optimal approaches for minimizing both the toxicity and the burden of treatment, all in the context of the evolving surgical and systemic management of this common disease. It includes a discussion of new approaches in breast cancer radiotherapy, including hypofractionation and intensity modulation, as well as a discussion of promising avenues for future research.

Dosimetric and geometric evaluation of a novel stereotactic radiotherapy device for breast cancer: the GammaPod™

PURPOSE

A dedicated stereotactic gamma irradiation device, the GammaPod™ from Xcision Medical Systems, was developed specifically to treat small breast cancers. This study presents the first evaluation of dosimetric and geometric characteristics from the initial prototype installed at University of Maryland Radiation Oncology Department.

METHODS

The GammaPod™ stereotactic radiotherapy device is an assembly of a hemi-spherical source carrier containing 36 (60)Co sources, a tungsten collimator, a dynamically controlled patient support table, and the breast immobilization system which also functions as a stereotactic frame. The source carrier contains the sources in six columns spaced longitudinally at 60° intervals and it rotates together with the variable-size collimator to form 36 noncoplanar, concentric arcs focused at the isocenter. The patient support table enables motion in three dimensions to position the patient tumor at the focal point of the irradiation. The table moves continuously in three cardinal dimensions during treatment to provide dynamic shaping of the dose distribution. The breast is immobilized using a breast cup applying a small negative pressure, where the immobilization cup is embedded with fiducials also functioning as the stereotactic frame for the breast. Geometric and dosimetric evaluations of the system as well as a protocol for absorbed dose calibration are provided. Dosimetric verifications of dynamically delivered patient plans are performed for seven patients using radiochromic films in hypothetical preop, postop, and target-in-target treatment scenarios.

RESULTS

Loaded with 36 (60)Co sources with cumulative activity of 4320 Ci, the prototype GammaPod™ unit delivers 5.31 Gy/min at the isocenter using the largest 2.5 cm diameter collimator. Due to the noncoplanar beam arrangement and dynamic dose shaping features, the GammaPod™ device is found to deliver uniform doses to targets with good conformity. The spatial accuracy of the device to locate the radiation isocenter is determined to be less than 1 mm. Single shot profiles with 2.5 cm collimator are measured with radiochromic film and found to be in good agreement with respect to the Monte Carlo based calculations (congruence of FWHM less than 1 mm). Dosimetric verifications corresponding to all hypothetical treatment plans corresponding to three target scenarios for each of the seven patients demonstrated good agreement with gamma index pass rates of better than 97% (99.0% ± 0.7%).

CONCLUSIONS

Dosimetric evaluation of the first GammaPod™ stereotactic breast radiotherapy unit was performed and the dosimetric and spatial accuracy of this novel technology is found to be feasible with respect to clinical radiotherapy standards. The observed level of agreement between the treatment planning system calculations and dosimetric measurements has confirmed that the system can deliver highly complex treatment plans with remarkable geometric and dosimetric accuracy.

Tumor bed-to-skin distance using accelerated partial-breast irradiation with the strut-adjusted volume implant device

PURPOSE

Because of the risk of skin toxicity with single dwell position, single-lumen brachytherapy devices are sometimes contraindicated for tumor cavities 5-7mm from the skin surface. We discuss the use of multicatheter device to treat patients with tumor bed-to-skin distances <7mm.

METHODS AND MATERIALS

We treated 117 patients with accelerated partial-breast irradiation brachytherapy: 77 single-lumen and 40 multicatheter devices. A subset of 12 patients treated with SAVI(®) had bed-to-skin spacing <7mm. All patients had Tis-2N0 ductal carcinoma with negative margins. A total dose of 34.0Gy in 10 fractions was delivered twice daily. Planning target volume was created using computed tomography-based three-dimensional planning with a 1.0-cm expansion of the lumpectomy cavity. Skin dose was measured dosimetrically, with skin constraints <125% of the prescription. Toxicities were graded, and patients were assessed at various intervals.

RESULTS

Of the patients treated with the multicatheter device, 0% (0/12) had their device pulled. At 2 weeks after treatment, fewer than 50% of the patients had skin toxicities of Grades 1-2, all of which resolved by 6 months. The cosmetic outcome was good to excellent at followup.

CONCLUSIONS

Multicatheter devices permit well-tolerated accelerated partial-breast irradiation in patients with tumor cavities near the skin surface for which the single-lumen device may not be appropriate.