Accelerated partial breast irradiation

Weekly Concomitant Boost in Adjuvant Radiotherapy for Patients with Early Breast Cancer: Preliminary Results on Feasibility

Aims and background

Recent advances in the management of patients with breast cancer are focused toward the reduction of overall treatment time of radiotherapy by delivering a dose biologically equivalent to a standard schedule. The aim of the present study was to evaluate the feasibility and preliminary toxicity of a moderately hypofractionated whole breast irradiation schedule with the addition of a concomitant boost delivered to the tumor bed once-a-week in patients with early breast cancer submitted to conservative surgery.

Materials

We selected patients with pT1c and pT2 N0/N+ M0 carcinoma of the breast with negative surgical margins. The basic course consisted of 4600 cGy prescribed to the ICRU 50 reference point dose and delivered in 20 fractions, 4 times a week for 5 weeks. Once a week, immediately after whole breast irradiation, a concomitant photon boost of 120 cGy was delivered to the lumpectomy area. Overall, according to the linear-quadratic model, the schedule provides a biologically equivalent dose of 87 Gy for breast tumor (assuming α/β = 4 Gy), of 66 Gy for acute responding normal tissues (assuming α/β = 10 Gy), and 99 Gy for late responding normal tissues (assuming α/β = 3 Gy). Biologically, the schedule compares favorably with the 6-week conventional regimen consisting of 50 Gy, 2 Gy/fraction, followed by a 10 Gy boost (BEDtumor,90 Gy; BEDacute effects, 72 Gy, and BEDlate effects, 100 Gy).

Results

From November 2004 to April 2007, we tested this radiotherapy schedule in 176 patients. All enrolled patients had achieved a minimum follow-up of 6 months and were considered in detail for the evaluation of feasibility. Three clinical examinations were performed by a group of independent physicians at treatment end, after 1 month and after 6 months. According to the RTOG/EORTC Toxicity Criteria, of the 176 assessable patients at the end of radiotherapy, 58% showed grade 0–1 skin toxicity, 30% grade 2 and 12% grade 3. At one month of follow-up, grade 0 toxicity was observed in 47% of cases, grade 1 in 46% and grade 2 in 7%. At 6 months, late (skin and subcutaneous tissue) toxicity was assessed with the following scores: grade 0 in 68%, grade 1 in 26% and grade 2 in 6% of the patients. At 6 months, cosmesis was excellent, good and fair in 71%, 24% and 5% of patients, respectively.

Conclusions

The explored adjuvant schedule planned to intensify the radiotherapy course for patients with early breast cancer by adding a weekly concomitant boost appears to be feasible and provides low local toxicity and excellent to good short-term cosmetic results.

Long-Term Cancer Outcomes From Study NRG Oncology/RTOG 9517: A Phase 2 Study of Accelerated Partial Breast Irradiation With Multicatheter Brachytherapy After Lumpectomy for Early-Stage Breast Cancer

PURPOSE

To examine 10-year rates of local, regional, and distant recurrences, patterns of recurrence, and survival rates for breast cancer patients enrolled on Study NRG Oncology/Radiation Therapy Oncology Group 9517, a multi-institutional prospective trial that studied one of the earliest methods of accelerated partial breast irradiation (APBI), multicatheter brachytherapy (MCT).

METHODS AND MATERIALS

Eligibility included stage I/II unifocal breast cancer <3 cm in size after lumpectomy with negative surgical margins and 0 to 3 positive axillary nodes without extracapsular extension. The APBI dose delivered was 34 Gy in 10 twice-daily fractions over 5 days for high-dose-rate (HDR); and 45 Gy in 3.5 to 5 days for low-dose-rate (LDR) brachytherapy. The primary endpoint was HDR and LDR MCT reproducibility. This analysis focuses on long-term ipsilateral breast recurrence (IBR), contralateral breast cancer events (CBE), regional recurrence (RR), and distant metastases (DM), disease-free, and overall survival.

RESULTS

The median follow-up was 12.1 years. One hundred patients were accrued from 1997 to 2000; 98 were evaluable; 65 underwent HDR and 33 LDR MCT. Median age was 62 years; 88% had T1 tumors; 81% were pN0. Seventy-seven percent were estrogen receptor and/or progesterone receptor positive; 33% received adjuvant chemotherapy and 64% antiendocrine therapy. There have been 4 isolated IBRs and 1 IBR with RR, for 5.2% 10-year IBR without DM. There was 1 isolated RR, 1 with IBR, and 1 with a CBE, for 3.1% 10-year RR without DM. The 10-year CBE rate was 4.2%, with 5 total events. Eleven patients have developed DM, 8 have died of breast cancer, and 22 have died from other causes. The 10-year DFS and OS rates are 69.8% and 78.0%, respectively.

CONCLUSION

This multi-institutional, phase 2 trial studying MCT-APBI continues to report durable in-breast cancer control rates with long-term follow-up.

Intraoperative Boost Radiotherapy during Targeted Oncoplastic Breast Surgery: Overview and Single Center Experiences

Breast-conserving surgery followed by whole-breast irradiation is the standard local therapy for early breast cancer. The international discussion of reduced importance of wider tumor-free resection margins than "tumor not touching ink" leads to the development of five principles in targeted oncoplastic breast surgery. IORT improves local recurrence risk and diminishes toxicity since there is less irradiation of healthy tissue. Intraoperative radiotherapy (IORT) can be delivered in two settings: an IORT boost followed by a conventional regimen of external beam radiotherapy or a single IORT dose. The data from TARGIT-A and ELIOT reinforce the conviction that intraoperative radiotherapy during breast-conserving surgery is a reliable alternative to conventional postoperative fractionated irradiation, but only in a carefully selected population at low risk of local recurrence. We describe our experiences with IORT boost (50 kV energy X-rays; 20 Gy) in combination with targeted oncoplastic breast surgery in a routine clinical setting. Our experiences demonstrate the applicability and reliability of combining IORT boost with targeted oncoplastic breast surgery in breast-conserving therapy of early breast cancer.

Accelerated partial breast irradiation for breast cancer: a meta-analysis

To evaluate the long-term effect of breast conservation with accelerated partial breast irradiation (APBI) for early-stage breast cancer, PubMed, EMBASE, Cochrane Library, Web of Science, Chinese Biomedical Literature Database, Chinese Scientific Journals Full-text Database, and China Journal Full-text Database were searched to identify relevant original published trials. Randomized controlled trials in any language comparing APBI with whole-breast radiotherapy in patients with early-stage breast cancer were included. RevMan 5 software was used for statistical analysis. Four trials involving 919 patients were included. The rate of 5- and 7-year excellent/good cosmetic results was significant {odds ratio (OR) = 2.09 [95% confidence interval (CI) = 1.21-3.62]} between two groups. The 5- and 8-year overall survival had no significant difference [OR = 1.76 (95% CI = 0.67-4.62) and OR = 0.86 (95% CI = 0.44-1.66)]. The 10-year overall survival had significant differences [OR = 0.56 (95% CI = 0.35-0.91)]. There were no differences in the 5-year local recurrence (LR)-free survival [OR = 0.65 (95% CI = 0.18-2.34)], cancer-specific survival [OR = 1.67 (95% CI = 0.39-7.12)], disease-free survival [OR = 0.84 (95% CI = 0.38-1.84)], LR [OR = 1.36 (95% CI = 0.46-3.99)], the rate of contralateral breast cancer [OR = 2.82 (95% CI = 0.73-10.89)], and distant metastasis [OR = 0.71 (95% CI = 0.22-2.31)]. APBI significantly improved the rate of excellent/good cosmetic results anywhere in the breast, shortened the treatment time, alleviated the pain, and improved the quality of life. Future large-scale, high-quality, and double-blind trials are needed.

Accelerated partial breast irradiation with intraoperative electrons: using GEC-ESTRO recommendations as guidance for patient selection

PURPOSE

To evaluate outcomes among early-stage breast cancer patients after conservative surgery and full-dose intraoperative radiotherapy electrons (ELIOT) by applying the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) recommendations for partial breast irradiation (APBI).

MATERIALS AND METHODS

One-thousand eight-hundred and twenty-two patients were stratified into the three GEC-ESTRO categories of "good candidates", "possible candidates" and "contraindication" in order to assess outcomes.

RESULTS

All the 1822 cases except 7 could be classified according to GEC-ESTRO groups: 573 patients met the criteria to be included in the "good candidates" group, 468 patients in the "possible candidates" group and 767 patients in the "contraindication" group. Median and mean follow-up length was 3.5 years (range 0-10.5 years) and 3.8 years (SD 2.2), respectively. The 5-year rate of in-breast tumor reappearances for "good candidates", "possible candidates" and "contraindication" groups were 1.9%, 7.4% and 7.7%, respectively (p 0.001). While the regional node relapse showed no difference, the rate of distant metastases was significantly different in the "contraindication" group compared to the other two categories, having a significant impact on survival.

CONCLUSIONS

Among the ELIOT population, the GEC-ESTRO recommendations enabled the selection of the good candidates with a low rate of local recurrence, but failed to differentiate the "possible candidates" and the "contraindication" groups.

Accelerated partial breast irradiation in early breast cancer: focus on intraoperative treatment with electrons (ELIOT)

Wide tumor resection plus postoperative whole breast irradiation is standard treatment for early breast cancer. Irradiation decreases recurrence rates, but may cause poor cosmesis, breast pain, and cardiac and lung toxicity. Accelerated partial breast irradiation is increasingly used in the hope of increasing convenience, decreasing sequelae and maintaining cure rates. Intraoperative radiotherapy with electrons is an attractive accelerated partial breast irradiation technique because collimator placement is under the direct control of the surgeon who removes the tumor, the skin is spared, shielding protects the chest wall and complete irradiation can be given in a single intraoperative session (avoiding 5-7 weeks of whole breast irradiation). Intraoperative radiotherapy with electrons seems as safe as whole breast irradiation; however, long-term results on local control and survival are not available yet.

Local control following single-dose intraoperative radiotherapy prior to surgical excision of early-stage breast cancer

BACKGROUND

Multiple partial breast radiotherapy techniques are available. We have previously presented the technical details of our procedure of delivering partial breast irradiation with a single fraction of intraoperative radiotherapy (IORT) targeting the tumor in situ prior to partial mastectomy. This study details our completed, single-institution trial.

MATERIALS AND METHODS

An IRB-approved, DSMB-monitored phase II trial was performed with the following inclusion criteria: women age ≥48, ultrasound-visible invasive ductal cancers <3 cm, clinically negative axillary nodes. IORT was delivered using mobile electron irradiator, at least a 1.5-cm radial and 1-cm deep margin; patients received 15 Gy and immediately underwent partial mastectomy. Ipsilateral breast recurrence was classified as true/marginal, elsewhere in the breast or nodal basin. Kaplan-Meier methods were used to estimate survival functions and exact 95% confidence intervals are reported.

RESULTS

Between 2003 and 2007, 71 women underwent IORT (median follow-up: 3.5 years). For patients with tumor-involved or close margins, additional therapy was required: 7 patients, total mastectomy; 11, whole breast radiation. Four women experienced invasive ipsilateral breast failures (1 new primary, 3 margin recurrences) for a 3-year local control rate of 49 of 53 (94.8%; 95% confidence interval 92.4% [95% CI] 84.2–98.3%), actuarial three-year in breast recurrence was 8% (95% CI 2–18%), and breast cancer-specific survival was 100%.

CONCLUSIONS

Intraoperative radiotherapy delivered to an in situ tumor is feasible, but our local control rate at 3.5 years is concerning. Possible changes to this technique to improve local control rates include better preoperative imaging (MRI), routine intraoperative ultrasound, and improved IORT delivery (larger cone, increased dose).

Surgical perspectives from a prospective, nonrandomized, multicenter study of breast conserving surgery and adjuvant electronic brachytherapy for the treatment of breast cancer

BACKGROUND

Accelerated partial breast irradiation (APBI) may be used to deliver radiation to the tumor bed post-lumpectomy in eligible patients with breast cancer. Patient and tumor characteristics as well as the lumpectomy technique can influence patient eligibility for APBI. This report describes a lumpectomy procedure and examines patient, tumor, and surgical characteristics from a prospective, multicenter study of electronic brachytherapy.

METHODS

The study enrolled 65 patients of age 45-84 years with ductal carcinoma or ductal carcinoma in situ, and 44 patients, who met the inclusion and exclusion criteria, were treated with APBI using the Axxent® electronic brachytherapy system following lumpectomy. The prescription dose was 34 Gy in 10 fractions over 5 days.

RESULTS

The lumpectomy technique as described herein varied by site and patient characteristics. The balloon applicator was implanted by the surgeon (91%) or a radiation oncologist (9%) during or up to 61 days post-lumpectomy (mean 22 days). A lateral approach was most commonly used (59%) for insertion of the applicator followed by an incision site approach in 27% of cases, a medial approach in 5%, and an inferior approach in 7%. A trocar was used during applicator insertion in 27% of cases. Local anesthetic, sedation, both or neither were administered in 45%, 2%, 41% and 11% of cases, respectively, during applicator placement. The prescription dose was delivered in 42 of 44 treated patients.

CONCLUSIONS

Early stage breast cancer can be treated with breast conserving surgery and APBI using electronic brachytherapy. Treatment was well tolerated, and these early outcomes were similar to the early outcomes with iridium-based balloon brachytherapy.

Intraoperative radiotherapy as accelerated partial breast irradiation for early breast cancer : beware of one-stop shops?

Intraoperative radiotherapy (IORT) was originally introduced in breast cancer treatment as an "anticipated boost" during the procedure of breast conserving surgery (BCS). In addition to whole breast irradiation (WBI), it has yielded excellent long-term results [31, 38]. Under the assumption that the majority of in-breast tumor recurrences (IBTR) occur in the originally affected site, accelerated partial breast irradiation (APBI) as the sole treatment modality was initiated in several studies and with different techniques, one of which was IORT first with electrons, later also with conventional x-rays [29]. The question whether and for whom the gold standard of WBI may be replaced by APBI - especially IORT - alone has recently been one of the most controversial issues of adjuvant therapy for breast cancer. Two recently published studies by Veronesi et al. [36] and Vaidya et al. [35] presenting shortterm results of single shot IORT with electrons (ELIOT) and with an orthovoltage system (TARGIT), respectively, have further invigorated this discussion as illustrated by several letters to the editor commenting on the TARGIT study. While Vaidya et al. [35] indicate their results of IORT alone as "an alternative to WBI for selected patients" and one editorial even proclaims it as standard [6], all the authors of the respective letters [10, 16, 27, 33] strongly disagree with this conclusion. The present editorial comments on the two publications and, furthermore, provides respective statements of the breast cancer expert panel of the German Society of Radiation Oncology (DEGRO).

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.

Dosimetric effects of air pocket sizes in MammoSite treatment as accelerated partial breast irradiation for early breast cancer

MammoSite brachytherapy system has been used as one of the accelerated partial breast irradiation (APBI) techniques since 2002. The clinical results from several clinical institutions had shown comparable treatment efficacy, cosmesis, and toxicity to other APBI techniques. During MammoSite treatment, air cavities had been one of the primary issues causing treatment cancellation or delay. With the tolerance of the air volume less than 10% of the total Planning Target Volume (PTV) set, there is still no data available to show the actual dose delivered to the breast tissue with the existence of the air pocket. In this paper, Monte Carlo N‐Particle version 5 (MCNP5) was used to model a hypothesis MammoSite phantom with different sizes of air pockets, and compared to the calculation results from the treatment planning system (TPS) without heterogeneous corrections. It was found that without heterogeneous corrections, the difference between the TPS and MCNP5 calculations in the air cavity surface doses and PTV point doses can be up to 2.02% and 3.61%, respectively, using the balloon and air pocket size combinations calculated in this paper. Based on the distance from the point of interest to the balloon surface, an approximate dose can be calculated using the linear relationship found in this study. These equations provide a quick and simple way to predict the actual dose delivered to the breast soft tissue located within the PTV. With the equation applied to the dose from the TPS, the dose error caused by the air pocket during MammoSite treatment can be reduced to a minimum.

PACS number: 87.53.Jw

[Practical dosimetry and constancy check at introduction of intraoperative radiotherapy with Intrabeam (Zeiss)]

The check of dosimetry of the intraoperative radiotherapy system Intrabeam is predefined by the manufacture (Zeiss). The purpose of the study was to develop and implement a method to verify the internal dosimetry of Intrabeam (Zeiss). Additionally the long-term stability of Intrabeam was checked for dose and isotropy. For dose to water measurements an Unidos was combined with a soft jet chamber (TM 23342) which was calibrated in water absorbed dose and as a phantom the type 2962 (PTW Freiburg) was used. RW1 plates were inserted as build up material. The applicators were placed in a bag filled with water to consider the side-scattering. At the surface of the applicator there was a mean difference of 3 percent between the dose to water measurement and the internal dosimetry. The constancy of the dose rate showed a mean deviation of 0.3% at the reference point. The analysis of the dose distribution perpendicular to the applicator axis z (reference z-axis) resulted in a mean deviation of -2.7% (x-direction) and -7,1% (-x-direction) for the x-axis and, respectively -4.1% (y-direction) and -5.3% (-y-direction) for the y-axis. The proposed method is suitable to verify the absolute dose of Intrabeam. The dose values measured by this method were congruent to the dosimetry of the manufacture (Zeiss). From our point of view it is sufficient to verify the absolute dosimetry only at time of commissioning of the system or in the case of changing the applicator. For the daily routine the check of constancy specified by the manufacture is adequate, because the dose rate is checked on a daily basis. Additionally the test of constancy showed a high long-term stability in terms of dose rate and symmetry.

Accelerated partial breast irradiation: initial experience with the Intrabeam System

Failure after breast conserving surgery (BCS) and total breast irradiation usually occurs at the site of the original tumor. This has caused an increased interest in accelerated partial breast irradiation (APBI), because if radiation is delivered directly to the tumor bed there should be better local control. Patients greater than age 50 with core biopsy confirmed invasive ductal carcinoma were enrolled. They had preoperative ultrasound defining margins of less than 3.5 cm. Intraoperative ultrasound was also performed in an effort to ensure good surgical margins. After excision of the tumor, intraoperative radiotherapy (IORT) with the Intrabeam System was delivered to the tumor bed. The procedure has been performed on 67 patients. Sixty-one patients had it with the original surgery, while 6 had the procedure after re-exploration of the segmental mastectomy site. Because of the final pathology (surgical margins, tumor biology, and nodal status) 4 patients later had total mastectomy and 11 received total breast irradiation. When total breast irradiation is done the IORT serves as the radiation boost. The cosmetic results have been good to excellent, and there have been no serious surgical or radiation complications. To date there have been no local failures. IORT with the Intrabeam System is feasible, user friendly, versatile, with few complications, good cosmetic results, and great patient acceptance. It is practical and excellent for breast IORT in the community setting.

The influence of different IMRT techniques on the peripheral dose: a comparison between sMLM-IMRT and helical tomotherapy

PURPOSE

To investigate how segmented multileaf modulation-(sMLM-)based intensity-modulated radiotherapy (IMRT) and dynamic helical tomotherapy (ToTh) affect the peripheral dose (PD) outside the treated region.

MATERIAL AND METHODS

A cuboid Perspex phantom was scanned in a computed tomograph. Different artificial cases were contoured consisting of OARs surrounded by cylindrically shaped planning target volumes (PTVs) with different dimensions. Radiotherapy plans were generated with the sMLM system Konrad (Siemens) and with the ToTh planning system. The plans were optimized in such a way that the dose-volume histograms showed comparable results. The sMLM plans were applied with a linac Primus (Siemens OCS), the ToTh plans with the HiArt system (TomoTherapy); both with 6 MV. Measurements of PDs were performed along the longitudinal axis of the phantom outside the primary beam at different distances from the edge of the PTV (horizontal PD) and also at different depths at a fixed distance from the isocenter (vertical PD). Additional experiments to separate the scatter dose caused by the phantom were performed. This was realized by removing the part of the phantom lying in the primary beam, then applying the same plans like before.

RESULTS

All PD values were normalized to the median dose of the PTV. The PD values for the different PTVs decrease with decreasing PTV size. They also decrease with increasing distance from the isocenter. The horizontal values are in a range of 7% for the largest PTV (diameter = 15 cm) near the primary dose region to 0.2% for the smallest PTV (diameter = 5 cm) far from the primary dose region. The ToTh values are higher than the sMLM values by a maximal factor of 2 near the primary dose region. They become more similar with increasing distance from the edge of the PTV in longitudinal direction. The PD values are nearly equal at a distance of 25 cm from the edge of the PTV. The vertical PDs are higher for the ToTh at depths of > 1 cm but higher for sMLM close to the surface. By removing the scatter cube, the horizontal PD values at middle distances are reduced to one third of the PD values with scatter cube for ToTh (0.5%) and to one half for sMLM (0.8%). This means that without scatter cube the PD for ToTh is lower than that for sMLM. The measured PD values without scatter cube are in the same dimension as published data.

CONCLUSION

The increasing PDs and their trend with increasing PTV size can be explained by Compton scattering of photons from the irradiated volume toward the off-axis measuring points. The further increase of the PD in case of ToTh relative to sMLM is not easy to explain. Different presumptions are possible. The larger field length (in longitudinal direction) of the ToTh plans (consisting of the "real" field length and the overlap) relative to the sMLM plans could be one reason for the higher PD values. The softer energy spectrum of the HiArt machine with more sideward Compton scattering contributions could be another reason.

Breast radiotherapy: considerations in older patients

With an ageing population, the number of older women with breast cancer eligible for adjuvant irradiation after breast conserving surgery and mastectomy is rising. There is a dearth of level 1 data on the effect of adjuvant irradiation on local control, quality of life and survival. In large part this reflects the exclusion of patients over the age of 70 years from randomised trials. The prevention of local recurrence may reduce the risks of dissemination. However, older women with early breast cancer and a life expectancy of less than 5 years are unlikely to derive a survival benefit from adjuvant radiotherapy. Rates of access of older patients to adjuvant irradiation are lower than for younger patients. Physician and patient bias and co-morbidities are contributory factors. There are also competing risks of mortality from co-morbidities, particularly in women over the age of 80 years. Postoperative radiotherapy after breast conserving surgery does not seem to compromise overall quality of life of older patients. Although the absolute reduction in local recurrence from adjuvant radiotherapy is modest in lower risk older patients after breast conserving surgery and adjuvant systemic therapy, there has to date been no group of fitter old patients defined from whom radiotherapy can be reasonably omitted. Guidelines for postmastectomy radiotherapy should not differ from younger patients. Adequately powered randomised trials are needed to assess the effect of adjuvant irradiation in older patients on outcomes after breast conserving surgery and mastectomy to provide a more robust basis for evidence-based radiotherapy practice.