Partial breast irradiation with interstitial 60CO brachytherapy results in frequent grade 3 or 4 toxicity. evidence based on a 12-year follow-up of 70 patients

Ultrasound Histogram Assessment of Acute Breast Toxicity After Breast Cancer Radiation Therapy: A Prospective Longitudinal Study

Accurate assessment of radiation-induced breast toxicity is crucial for the management of breast radiation therapy (RT). Standard assessment of breast toxicity based on clinicians' visual inspection and palpation has considerable inter- and intra-observer variability. To overcome this challenge, we present an ultrasound histogram method that objectively evaluates radiation-induced breast toxicity longitudinally. In a prospective study, patients enrolled (n = 67) received ultrasound scans at four time points: prior to RT, last day of RT, 3-4 wk post-RT and 9-12-wk post-RT. Ultrasound scans were acquired at five locations (tumor bed and 3, 6, 9 and 12 o'clock) on both breasts. Two hundred sixty-four ultrasound scans and 2640 B-mode images were analyzed. The histogram differences between irradiated and contralateral breasts were calculated to evaluate radiation-induced breast changes. On the basis of the B-mode images, the severity of breast toxicity was graded as absent, mild, moderate or severe. The performance of the histogram method was assessed with the receiver operating characteristic (ROC) curve. The areas under the ROC curve ranged from 0.78 to 0.9 (sensitivity: 0.88-0.96, specificity: 0.53-0.83) at the lower quadrant for differentiating absent/mild from moderate/severe toxicity at various time points. This study provides preliminary evidence that ultrasound histogram differences can serve as an imaging biomarker to longitudinally assess radiation-induced acute toxicity.

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.

Fat necrosis of the breast in the accelerated partial breast irradiation era: the need for a universal grading system

Fat necrosis of the breast is increasingly reported and used as a trial endpoint in the treatment of breast cancer with accelerated partial breast irradiation (APBI). Yet, there is no universal toxicity scoring system within the latest version of the Common Terminology Criteria for Adverse Events (CTCAE v4.0). This requires investigators to adopt their own scoring system or improperly use those that exist, and limits accurate reporting of this entity. Fat necrosis of the breast also creates diagnostic uncertainty among clinicians and concern of recurrence among patients. In this review, we address the question of increasing incidence of fat necrosis through the comparison of recent APBI trials and literature. The pathogenesis, symptoms, clinical and radiologic diagnosis, clinical predictors of developing fat necrosis, management and follow-up are also discussed.Lastly, we propose a simplified and universal scoring system for the reporting of fat necrosis.

Breast-conserving therapy with partial or whole breast irradiation: ten-year results of the Budapest randomized trial

BACKGROUND AND PURPOSE

To report the long-term results of a single-institution randomized study comparing the results of breast-conserving treatment with partial breast irradiation (PBI) or conventional whole breast irradiation (WBI).

PATIENTS AND METHODS

Between 1998 and 2004, 258 selected women with pT1 pN0-1mi M0, grade 1-2, non-lobular breast cancer without the presence of extensive intraductal component and resected with negative margins were randomized after BCS to receive 50 Gy WBI (n=130) or PBI (n=128). The latter consisted of either 7 × 5.2 Gy high-dose-rate (HDR) multi-catheter brachytherapy (BT; n=88) or 50 Gy electron beam (EB) irradiation (n=40). Primary endpoint was local recurrence (LR) as a first event. Secondary endpoints were overall survival (OS), cancer-specific survival (CSS), disease-free survival (DFS), and cosmetic results.

RESULTS

After a median follow up of 10.2 years, the ten-year actuarial rate of LR was 5.9% and 5.1% in PBI and WBI arms, respectively (p=0.77). There was no significant difference in the ten-year probability of OS (80% vs 82%), CSS (94% vs 92%), and DFS (85% vs 84%), either. The rate of excellent-good cosmetic result was 81% in the PBI, and 63% in the control group (p<0.01).

CONCLUSIONS

Partial breast irradiation delivered by interstitial HDR BT or EB for a selected group of early-stage breast cancer patients produces similar ten-year results to those achieved with conventional WBI. Significantly better cosmetic outcome can be achieved with HDR BT implants compared with the outcome after WBI.

The American Brachytherapy Society consensus statement for accelerated partial breast irradiation

PURPOSE

To develop clinical guidelines for the quality practice of accelerated partial breast irradiation (APBI) as part of breast-conserving therapy for women with early-stage breast cancer.

METHODS AND MATERIALS

Members of the American Brachytherapy Society with expertise in breast cancer and breast brachytherapy in particular devised updated guidelines for appropriate patient evaluation and selection based on an extensive literature search and clinical experience.

RESULTS

Increasing numbers of randomized and single and multi-institution series have been published documenting the efficacy of various APBI modalities. With more than 10-year followup, multiple series have documented excellent clinical outcomes with interstitial APBI. Patient selection for APBI should be based on a review of clinical and pathologic factors by the clinician with particular attention paid to age (≥50 years old), tumor size (≤3cm), histology (all invasive subtypes and ductal carcinoma in situ), surgical margins (negative), lymphovascular space invasion (not present), and nodal status (negative). Consistent dosimetric guidelines should be used to improve target coverage and limit potential for toxicity following treatment.

CONCLUSIONS

These guidelines have been created to provide clinicians with appropriate patient selection criteria to allow clinicians to use APBI in a manner that will optimize clinical outcomes and patient satisfaction. These guidelines will continue to be evaluated and revised as future publications further stratify optimal patient selection.

Reliability of quantitative ultrasonic assessment of normal-tissue toxicity in breast cancer radiotherapy

PURPOSE

We have recently reported that ultrasound imaging, together with ultrasound tissue characterization (UTC), can provide quantitative assessment of radiation-induced normal-tissue toxicity. This study's purpose is to evaluate the reliability of our quantitative ultrasound technology in assessing acute and late normal-tissue toxicity in breast cancer radiotherapy.

METHOD AND MATERIALS

Our ultrasound technique analyzes radiofrequency echo signals and provides quantitative measures of dermal, hypodermal, and glandular tissue toxicities. To facilitate easy clinical implementation, we further refined this technique by developing a semiautomatic ultrasound-based toxicity assessment tool (UBTAT). Seventy-two ultrasound studies of 26 patients (720 images) were analyzed. Images of 8 patients were evaluated for acute toxicity (<6 months postradiotherapy) and those of 18 patients were evaluated for late toxicity (≥ 6 months postradiotherapy). All patients were treated according to a standard radiotherapy protocol. To assess intraobserver reliability, one observer analyzed 720 images in UBTAT and then repeated the analysis 3 months later. To assess interobserver reliability, three observers (two radiation oncologists and one ultrasound expert) each analyzed 720 images in UBTAT. An intraclass correlation coefficient (ICC) was used to evaluate intra- and interobserver reliability. Ultrasound assessment and clinical evaluation were also compared.

RESULTS

Intraobserver ICC was 0.89 for dermal toxicity, 0.74 for hypodermal toxicity, and 0.96 for glandular tissue toxicity. Interobserver ICC was 0.78 for dermal toxicity, 0.74 for hypodermal toxicity, and 0.94 for glandular tissue toxicity. Statistical analysis found significant changes in dermal (p < 0.0001), hypodermal (p = 0.0027), and glandular tissue (p < 0.0001) assessments in the acute toxicity group. Ultrasound measurements correlated with clinical Radiation Therapy Oncology Group (RTOG) toxicity scores of patients in the late toxicity group. Patients with RTOG Grade 1 or 2 had greater ultrasound-assessed toxicity percentage changes than patients with RTOG Grade 0.

CONCLUSION

Early and late radiation-induced effects on normal tissue can be reliably assessed using quantitative ultrasound.

Accelerated Partial Breast Irradiation: Potential Roles following Breast-Conserving Surgery

Background

Multiple randomized trials comparing mastectomy to lumpectomy and whole breast irradiation (WBI) have shown equivalent survival outcomes in early-stage breast cancer. WBI requires a treatment course of several weeks, which has resulted in limited access to breast-conserving therapy in certain populations. A shorter accelerated course of partial breast irradiation (APBI) has been investigated recently.

Methods

This article reviews the current medical literature, including randomized trials and prospective institutional studies of APBI and the current recommendations regarding the use of this emerging technique.

Results

Several APBI techniques have been developed, including brachytherapy and external beam methods. The longest follow-up data are available for multicatheter interstitial brachytherapy, a technique that is not commonly used. Other methods, including balloon brachytherapy and external beam three-dimensional conformal techniques, have limited follow-up that shows similar local control rates to whole breast irradiation in highly selected patients. Guidelines for the appropriate use of APBI have been published.

Conclusions

While APBI may increase access to breast conservation therapy for some women with early-stage breast cancer, follow-up data demonstrating the efficacy of this relatively new treatment approach are limited. Therefore, strict evidence-based selection criteria should be applied when evaluating patients who may be appropriate for APBI.

Cosmetic outcomes for accelerated partial breast irradiation before surgical excision of early-stage breast cancer using single-dose intraoperative radiotherapy

PURPOSE

Determine cosmetic outcome and toxicity profile of intraoperative radiation delivered before tumor excision for patients with early-stage breast cancer.

METHODS AND MATERIALS

Patients age 48 or older with ultrasound-visible invasive ductal cancers <3 cm and clinically negative lymph nodes were eligible for treatment on this institutional review board-approved Phase II clinical trial. Treatment planning ultrasound was used to select an electron energy and cone size sufficient to cover the tumor plus a 1.5- to 2.0-cm circumferential margin laterally and a 1-cm-deep margin with the 90% isodose line. The dose was prescribed to a nominal 15 Gy and delivered using a Mobetron electron irradiator before tumor excision by segmental mastectomy. Physician- and patient-assessed cosmetic outcome and patient satisfaction were determined by questionnaire.

RESULTS

From March 2003 to July 2007, 71 patients were treated with intraoperative radiation therapy. Of those, 56 patients were evaluable, with a median follow-up of 3.1 years (minimum 1 year). Physician and patient assessment of cosmesis was "good or excellent" (Radiation Therapy Oncology Group cosmesis scale) in 45/56 (80%) and 32/42 (76%) of all patients, respectively. Eleven patients who received additional whole breast radiation had similar rates of good or excellent cosmesis: 40/48 (83%) and 29/36 (81%), respectively). Grade 1 or 2 acute toxicities were seen in 4/71 (6%) patients. No Grade 3 or 4 toxicities or serious adverse events have been seen.

CONCLUSION

Intraoperative radiotherapy delivered to an in situ tumor is feasible with acceptable acute tolerance. Patient and physician assessment of the cosmetic outcome is good to excellent.

Patient selection for accelerated partial-breast irradiation (APBI) after breast-conserving surgery: recommendations of the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) breast cancer working group based on clinical evidence (2009)

PURPOSE

To give recommendations on patient selection criteria for the use of accelerated partial-breast irradiation (APBI) based on available clinical evidence complemented by expert opinion.

METHODS AND MATERIALS

Overall, 340 articles were identified by a systematic search of the PubMed database using the keywords "partial-breast irradiation" and "APBI". This search was complemented by searches of reference lists of articles and handsearching of relevant conference abstracts and book chapters. Of these, 3 randomized and 19 prospective non-randomized studies with a minimum median follow-up time of 4 years were identified. The authors reviewed the published clinical evidence on APBI, complemented by relevant clinical and pathological studies of standard breast-conserving therapy and, through a series of personal communications, formulated the recommendations presented in this article.

RESULTS

The GEC-ESTRO Breast Cancer Working Group recommends three categories guiding patient selection for APBI: (1) a low-risk group for whom APBI outside the context of a clinical trial is an acceptable treatment option; including patients ageing at least 50 years with unicentric, unifocal, pT1-2 (<or=30 mm) pN0, non-lobular invasive breast cancer without the presence of an extensive intraductal component (EIC) and lympho-vascular invasion (LVI) and with negative surgical margins of at least 2mm, (2) a high-risk group, for whom APBI is considered contraindicated; including patients ageing <or=40 years; having positive margins, and/or multicentric or large (>30 mm) tumours, and/or EIC positive or LVI positive tumours, and/or 4 or more positive lymph nodes or unknown axillary status (pNx), and (3) an intermediate-risk group, for whom APBI is considered acceptable only in the context of prospective clinical trials.

CONCLUSIONS

These recommendations will provide a clinical guidance regarding the use of APBI outside the context of a clinical trial before large-scale randomized clinical trial outcome data become available. Furthermore they should promote further clinical research focusing on controversial issues in the treatment of early-stage breast carcinoma.

Accelerated partial breast irradiation consensus statement from the American Society for Radiation Oncology (ASTRO)

PURPOSE

To present guidance for patients and physicians regarding the use of accelerated partial-breast irradiation (APBI), based on current published evidence complemented by expert opinion.

METHODS AND MATERIALS

A systematic search of the National Library of Medicine's PubMed database yielded 645 candidate original research articles potentially applicable to APBI. Of these, 4 randomized trials and 38 prospective single-arm studies were identified. A Task Force composed of all authors synthesized the published evidence and, through a series of meetings, reached consensus regarding the recommendations contained herein.

RESULTS

The Task Force proposed three patient groups: (1) a "suitable" group, for whom APBI outside of a clinical trial is acceptable, (2) a "cautionary" group, for whom caution and concern should be applied when considering APBI outside of a clinical trial, and (3) an "unsuitable" group, for whom APBI outside of a clinical trial is not generally considered warranted. Patients who choose treatment with APBI should be informed that whole-breast irradiation (WBI) is an established treatment with a much longer track record that has documented long-term effectiveness and safety.

CONCLUSION

Accelerated partial-breast irradiation is a new technology that may ultimately demonstrate long-term effectiveness and safety comparable to that of WBI for selected patients with early breast cancer. This consensus statement is intended to provide guidance regarding the use of APBI outside of a clinical trial and to serve as a framework to promote additional clinical investigations into the optimal role of APBI in the treatment of breast cancer.

Partial breast irradiation as sole therapy for low risk breast carcinoma: early toxicity, cosmesis and quality of life results of a MammoSite brachytherapy phase II study

PURPOSE

The MammoSite is a device that was developed with the goal of making breast-conserving surgery (BCT) more widely available. Our objective was to evaluate the MammoSite device performances after an open cavity placement procedure and quality of life in highly selected patients with early-stage breast cancer.

METHODS AND MATERIALS

From March 2003 to March 2005, 43 patients with T1 breast cancer were enrolled in a phase II study. The median age was 72 years. Twenty-five (58%) patients were treated with high-dose rate brachytherapy using the MammoSite applicator to deliver 34Gy in 10 fractions. The main disqualifying factor was pathologic sentinel node involvement (10/43; 23%). There were no device malfunctions, migration or rupture of the balloon.

RESULTS

After a median follow-up of 13 months, there were no local recurrences and one contralateral lobular carcinoma. Seventeen (68%), 13 (52%), 8 (32%), 5 (20%) and 2 (8%) patients had erythema, seroma, inflammation, hematoma and sever infection, respectively. Only 2 patients developed telangiectasia. At 1 year the rate of "good to excellent" cosmetic results was 84%. Significant changes in QoL were observed for emotional and social well-being between 3 and 12 months. At 24 months, only emotional well-being subscore changes were statistically significant (p=0.015).

CONCLUSIONS

Our data in patients older than 60 years support the previously published data. Histologic features were the main disqualifying criteria. With higher skin spacing levels we observed very low incidence of telangiectasia. QoL evaluation indicates that baseline scores were satisfactory. Changes concerned emotional and social well-being.

[Accelerated partial breast irradiation: a concept to individualize treatment in breast cancer]

Whole breast irradiation delivering an equivalent dose of 50 Gy in 5 weeks, followed by a 10 to 16 Gy-boost to the tumor bed is the standard of care after breast-conserving surgery for early-breast cancer. Accelerated partial breast irradiation (APBI) is currently under investigations in large multi-institutional, prospective, randomized trials to objectively address the critical endpoints of treatment efficacy, toxicity and cosmesis. Patient's selection for this new approach is crucial to individualise treatments and define the subgroups of patients who will really benefit from APBI in terms of quality of life without decreasing long-term results of the disease control and cosmesis. In this review, we will discuss the patients' profiles selection for APBI regarding their general and tumor criteria. The differences between APBI techniques either performed intra or post operatively will be also discussed.

Accelerated partial breast irradiation in early-stage breast cancer

Whole-breast irradiation, as part of breast-conservation therapy (BCT), has well-established results, good cosmesis, and low toxicity. Results from the BCT trials suggest that the risk for ipsilateral breast cancer recurrence resides within close proximity to the original tumor site. This leads investigators to consider the role of an accelerated and more tumor bed-focused course of radiotherapy. Accelerated partial-breast irradiation (APBI) involves treating a limited volume of breast tissue, with dose of irradiation per fraction increased and the treatment time course decreased. Four currently available methods of APBI are interstitial brachytherapy, intracavitary brachytherapy, intraoperative radiotherapy, and three-dimensional conformal external-beam radiotherapy. Patient selection is critical. This review article presents some preliminary clinical observations and limitations that suggest a potential role for APBI as a more user-friendly mode for delivering radiotherapy after lumpectomy for early breast cancer.

A Technique of Partial Breast Irradiation Utilizing Proton Beam Radiotherapy: Comparison with Conformal X-Ray Therapy

PURPOSE

To develop a breast immobilization system and clinical technique to deliver partial breast irradiation with a proton beam and compare dose distributions using proton therapy and conformal x-rays.

METHODS

A clinical technique to provide reproducible breast immobilization was developed. Breast immobilization begins by fitting each patient with a treatment brassiere. Patients are placed prone in a cylindrical polyvinyl chloride shell with the upper and lower body being supported and immobilized with Vac-Lok foam bead cushions. The upper chest and breast areas are immobilized with two-part expandable foam. After a treatment planning computed tomography scan, the lumpectomy cavity is outlined, and a clinical target volume is generated by adding 1cm in all dimensions. A three-dimensional treatment plan is developed with treatment typically given with 2 to 4 separate proton beams. The dose administered is 40 cobalt Gray equivalents (CGE) delivered in 10 daily fractions of 4 CGE with multiple fields treated each day. Proton and conformal x-ray plans were compared using dose-volume histogram analysis to determine volumes of normal breast tissue and skin treated with each technique.

RESULTS

An institutional review board-approved clinical trial was developed using this technique, and 20 patients have completed treatment. All subjects were able to undergo the immobilization procedure and daily treatments without significant discomfort, and no treatment interruptions were encountered. There was no evidence of respiratory motion identified on treatment planning CT images or on daily set-up radiographs. Acute toxicity has been limited to occasional radiation dermatitis (Radiation Therapy Oncology Group grade 1-2). Proton plans were compared with 2 methods of photon partial breast irradiation, including reduced tangential fields and five-field conformal techniques. Ten treatment plans with dose-volume histogram analysis revealed that the use of proton beams provided a significant reduction in doses to the ipsilateral breast and skin while eliminating doses to the heart and lung tissues.

CONCLUSIONS

A simple immobilization procedure provides accurate and reproducible breast positioning while simultaneously eliminating respiratory motion. The procedure has been well tolerated by the first 20 patients. Protons can provide substantial normal tissue protection compared with the use of conformal x-rays when used for partial breast treatment. We plan to continue enrollment and analyze long-term toxicity, local control, and survival.

Accelerated partial breast irradiation

BACKGROUND

Breast-conserving surgery followed by whole-breast radiotherapy (WBRT) has become the standard treatment for the majority of patients with early breast cancer. Whereas the indications for systemic adjuvant treatment have continuously expanded, there is a tendency to restrict postoperative radiotherapy to accelerated partial breast irradiation (APBI) instead of WBRT.

METHODS

The different techniques of APBI are described and their respective advantages or potential drawbacks outlined. Moreover, the results described in the literature are briefly reviewed as a basis for the consensus statements and recommendations of the German Society of Radiation Oncology, the German Society of Senology, and the Working Group for Gynecological Oncology of the German Cancer Society.

RESULTS

The methods mainly used for APBI are: interstitial radiotherapy with multicatheter technique, intraoperative radiotherapy (IORT) using either electrons produced by linear accelerators or 50 kV x-rays (Intrabeam), the balloon-catheter technique (MammoSite), or 3D conformal external beam radiotherapy. These techniques have marked differences in dose distribution and homogeneity. The published range of local recurrence rates varies between 0% to 37%, the median follow-up from 8 to 72 months.

CONCLUSIONS

To date, follow-up times mostly do not yet permit a definite judgment concerning the long-term effectiveness and side effects of APBI. The relevant societies in Germany support randomized clinical studies comparing APBI with WBRT in a well-defined subset of low-risk patients. However, the authors expressly discourage the routine use of APBI outside clinical trials. Until definite results show that APBI neither impairs therapeutic outcome nor cosmetic results, WBRT remains the gold standard in the treatment of early breast cancer.

Microarray analysis of radiation response genes in primary human fibroblasts

PURPOSE

To identify radiation-induced early transcriptional responses in primary human fibroblasts and understand cellular pathways leading to damage correction.

METHODS AND MATERIALS

Primary human fibroblast cell lines were irradiated with 2 Gy gamma-radiation and RNA isolated 2 h later. Radiation-induced transcriptional alterations were investigated with microarrays covering the entire human genome. Time- and dose dependent radiation responses were studied by quantitative real-time polymerase chain reaction (RT-PCR).

RESULTS

About 200 genes responded to ionizing radiation on the transcriptional level in primary human fibroblasts. The expression profile depended on individual genetic backgrounds. Thirty genes (28 up- and 2 down-regulated) responded to radiation in identical manner in all investigated cells. Twenty of these consensus radiation response genes were functionally categorized: most of them belong to the DNA damage response (GADD45A, BTG2, PCNA, IER5), regulation of cell cycle and cell proliferation (CDKN1A, PPM1D, SERTAD1, PLK2, PLK3, CYR61), programmed cell death (BBC3, TP53INP1) and signaling (SH2D2A, SLIC1, GDF15, THSD1) pathways. Four genes (SEL10, FDXR, CYP26B1, OR11A1) were annotated to other functional groups. Many of the consensus radiation response genes are regulated by, or regulate p53. Time- and dose-dependent expression profiles of selected consensus genes (CDKN1A, GADD45A, IER5, PLK3, CYR61) were investigated by quantitative RT-PCR. Transcriptional alterations depended on the applied dose, and on the time after irradiation.

CONCLUSIONS

The data presented here could help in the better understanding of early radiation responses and the development of biomarkers to identify radiation susceptible individuals.

Is partial breast irradiation a step forward or backward?

Partial-breast irradiation (PBI) may prove to be a significant advance in the treatment of selected patients with early-stage breast cancer. However, because PBI treats a much smaller volume of breast tissue than does conventional whole-breast irradiation and the biologic equivalent dose delivered to the tumor may be considerably lower, it is possible that this treatment approach may increase the risk of recurrence. There may also be an increased risk of toxicity using PBI techniques that have significant dose inhomogeneity. Despite these uncertainties, many patients in the United States are currently treated with PBI outside of a clinical study. Showing that PBI is safe and effective requires having results from large clinical trials. If such trials are supported and completed, the benefits and limitations of PBI are likely to be elucidated, and this treatment technique, properly refined, may well prove to be an advance in breast cancer care. If instead PBI is adopted ad hoc within the radiation oncology community without proper testing, it is likely that poor outcomes will be underreported and many patients will receive suboptimal therapy. This would be a big step backward in the role of radiation therapy in breast cancer treatment.

TLD skin dose measurements and acute and late effects after lumpectomy and high-dose-rate brachytherapy only for early breast cancer

PURPOSE

This report examines the relationships between measured skin doses and the acute and late skin and soft tissue changes in a pilot study of lumpectomy and high-dose-rate brachytherapy only for breast cancer.

METHODS AND MATERIALS

Thirty-seven of 39 women enrolled in this pilot study of high-dose-rate brachytherapy (37.2 Gy in 10 fractions b.i.d.) each had thermoluminescent dosimetry (TLD) at 5 points on the skin of the breast overlying the implant volume. Skin changes at TLD dose points and fibrosis at the lumpectomy site were documented every 6 to 12 months posttreatment using a standardized physician-rated cosmesis questionnaire. The relationships between TLD dose and acute skin reaction, pigmentation, or telangiectasia at 5 years were analyzed using the GEE algorithm and the GENMOD procedure in the SAS statistical package. Fisher's exact test was used to determine whether there were any significant associations between acute skin reaction and late pigmentation or telangiectasia or between the volumes encompassed by various isodoses and fibrosis or fat necrosis.

RESULTS

The median TLD dose per fraction (185 dose points) multiplied by 10 was 9.2 Gy. In all 37 patients, acute skin reaction Grade 1 or higher was observed at 5.9% (6 of 102) of dose points receiving 10 Gy or less vs. 44.6% (37 of 83) of dose points receiving more than 10 Gy (p < 0.0001). In 25 patients at 60 months, 1.5% telangiectasia was seen at dose points receiving 10 Gy or less (1 of 69) vs. 18% (10 of 56) telangiectasia at dose points receiving more than 10 Gy (p = 0.004). Grade 1 or more pigmentation developed at 1.5% (1 of 69) of dose points receiving less than 10 Gy vs. 25% (14 of 56) of dose points receiving more than 10 Gy (p < 0.001). A Grade 1 or more acute skin reaction was also significantly associated with development of Grade 1 or more pigmentation or telangiectasia at 60 months. This association was most significant for acute reaction and telangiectasia directly over the lumpectomy site (p < 0.001). Grade 1 or more fibrosis, in 25 patients with a 60-month follow-up, occurred in 47.4% (9 of 19) of patients with a volume of 45 cm3 or less covered by the 100% isodose vs. 83.3% (5 of 6) of patients with a larger volume (p = 0.180). Asymptomatic and biopsy-proven fat necrosis occurred in 5 patients. No significant differences in fat necrosis rates according to volume were detected.

CONCLUSIONS

For high-dose-rate brachytherapy to the lumpectomy site, TLD skin dose was significantly related to acute skin reaction and to pigmentation and telangiectasia at 60 months. An acute skin reaction was also significantly associated with the development of telangiectasia at 60 months. TLD skin dose measurement may allow modification of the brachytherapy implant geometry (dwell times and position) to minimize late skin toxicity.

Dose perturbations due to contrast medium and air in MammoSite® treatment: An experimental and Monte Carlo study

In the management of early breast cancer, a partial breast irradiation technique called MammoSite (Proxima Therapeutic Inc., Alpharetta, GA) has been advocated in recent years. In MammoSite, a balloon implanted at the surgical cavity during tumor excision is filled with a radio-opaque solution, and radiation is delivered via a high dose rate brachytherapy source situated at the center of the balloon. Frequently air may be introduced during placement of the balloon and/or injection of the contrast solution into the balloon. The purpose of this work is to quantify as well as to understand dose perturbations due to the presence of a high-Z contrast medium and/or an air bubble with measurements and Monte Carlo calculations. In addition, the measured dose distribution is compared with that obtained from a commercial treatment planning system (Nucletron PLATO system). For a balloon diameter of 42 mm, the dose variation as a function of distance from the balloon surface is measured for various concentrations of a radio-opaque solution (in the range 5%-25% by volume) with a small volume parallel plate ion chamber and a micro-diode detector placed perpendicular to the balloon axis. Monte Carlo simulations are performed to provide a basic understanding of the interaction mechanism and the magnitude of dose perturbation at the interface near balloon surface. Our results show that the radio-opaque concentration produces dose perturbation up to 6%. The dose perturbation occurs mostly within the distances <1 mm from the balloon surface. The Plato system that does not include heterogeneity correction may be sufficient for dose planning at distances > or = 10 mm from the balloon surface for the iodine concentrations used in the MammoSite procedures. The dose enhancement effect near the balloon surface (<1 mm) due to the higher iodine concentration is not correctly predicted by the Plato system. The dose near the balloon surface may be increased by 0.5% per cm3 of air. Monte Carlo simulation suggests that the interface effect (enhanced dose near surface) is primarily due to Compton electrons of short range (<0.5 mm). For more accurate dosimetry in MammoSite delivery, the dose perturbation due to the presence of a radio-opaque contrast medium and air bubbles should be considered in a brachytherapy planning system.

The evolution of accelerated, partial breast irradiation as a potential treatment option for women with newly diagnosed breast cancer considering breast conservation

Breast conservation therapy (BCT) is a safe, effective alternative to mastectomy for many women with newly diagnosed breast cancer. This approach involves local excision of the malignancy with tumor-free margins, followed by 5-7 weeks of external beam whole breast (WB) radiotherapy (XRT) to minimize the risk of an in-breast tumor recurrence (IBTR). Though clearly beneficial, the extended course of almost daily postoperative radiotherapy interrupts normal activities and lengthens care. Additional options are now available that shorten the radiotherapy treatment time to 1-5 days (accelerated) and focus an increased dose of radiation on just the breast tissue around the excision cavity (partial breast). Recent trials with accelerated, partial breast irradiation (APBI) have shown promise as a potential replacement to the longer, whole breast treatments for select women with early-stage breast cancer. Current APBI approaches include interstitial brachytherapy, intracavitary (balloon) brachytherapy, and accelerated external beam (3-D conformal) radiotherapy, all of which normally complete treatment over 5 days, while intraoperative radiotherapy (IORT) condenses the entire treatment into a single dose delivered immediately after tumor excision. Each approach has benefits and limitations. This study covers over 2 decades of clinical trials exploring APBI, discusses treatment variables that appear necessary for successful implementation of this new form of radiotherapy, compares and contrasts the various APBI approaches, and summarizes current and planned randomized trials that will shape if and how APBI is introduced into routine clinical care. Some of the more important outcome variables from these trials will be local toxicity, local and regional recurrence, and overall survival. If APBI options are ultimately demonstrated to be as safe and effective as current whole breast radiotherapy approaches, breast conservation may become an even more appealing choice, and the overall impact of treatment may be further reduced for certain women with newly diagnosed breast cancer.

Brachytherapy for partial breast irradiation: The European experience

There has been great interest in Europe in treating selected patients with early-stage breast cancer with accelerated partial breast irradiation (APBI) using interstitial brachytherapy. We review the results of these studies. Five early studies had local recurrence rates of 6% to 37%, reflecting suboptimal patient selection, target definition, and quality assurance procedures. Five more recent studies performed using much more stringent approaches have had recurrence rates of 0% to 7% with 84% to 92% of patients having excellent or good cosmetic results. The 3-year results of a single-institution phase III trial suggest that partial-breast brachytherapy performed in this manner yields local control that is very similar to that of whole-breast irradiation. Recently, a phase III multicenter protocol comparing these 2 modalities has been activated in Europe by the Breast Cancer Working Group of the Groupe Europeen de Curietherapie-European Society for Therapeutic Radiology and Oncology. As data from this and other trials mature, they will address and refine issues of patient selection, target volume definition, total dose, and fractionation and hopefully support the implementation of APBI into routine clinical practice.

Partial-breast treatment for early breast cancer: emergence of a new paradigm

Although hailed as a paradigm shift, the breast conservative treatment that emerged in the 1980s was in fact an extension of the Halstedian concept, wherein whole-breast irradiation (WBI) compensated for the limited surgery. Observations that 80-90% of breast recurrences after breast conservative surgery and WBI occur in the tumor bed questions the need for protracted elective WBI, and provides the rationale for accelerated-partial-breast irradiation (APBI) of small cancers without adverse features predisposing to multicentric recurrence. APBI can be given over a week with various external beam, intraoperative or brachytherapy (interstitial or MammoSite) techniques. Since the approval of MammoSite by the US FDA in May 2002, a surge of interest has been evident, with 4,000 cases treated using this technique in the past 2 years. Several phase II APBI brachytherapy studies show that 4 to 7-year breast control rates (95%), survival and cosmetic outcome obtained from more than 600 appropriately selected women are comparable to matched or historic controls receiving WBI. The 2 to 3-year interim results of two ongoing randomized trials do not show any early detriment with APBI. If mature results of randomized trials confirm equivalence of APBI to conventional WBI in selected women, it would mark a paradigm shift and a major advance in treatment. This would allow many more women to opt for breast conservation, resolve the dilemmas regarding chemotherapy and radiotherapy sequencing and perhaps would be more cost effective.

Sophisticated radiotherapy with optimal surgery is the way forward

PURPOSE OF REVIEW

Radiotherapy has been one of the cornerstones of treatment for breast cancer for more than a century and has contributed to conservation of the breast and improved locoregional control after mastectomy. This review assesses the most recent evidence generated by clinical scientists in the field of radiotherapy for breast cancer.

RECENT FINDINGS

Results from mature trials investigating the role of radiotherapy in breast cancer treatment and the publication of meta-analyses of treatment effects have shown that in addition to improvements in local control, a survival benefit is obtained in several disease settings. These include breast-conserving therapy and postmastectomy radiotherapy. Further, improved diagnostic abilities and surgical techniques, together with advances in treatment delivery, will help to increase the therapeutic ratio of radiotherapy.

SUMMARY

There is increasing evidence for long-term benefits of radiotherapy for breast cancer and a reduction in the risks of late side effects in recent decades. This can have a profound impact on clinical practice in the future, leading to a broadening and individualizing of the indications for radiotherapy and improvements in patient survival.