Abstract
Purpose:
To evaluate the efficacy and safety of the accelerated partial breast irradiation brachytherapy with a combination of applicators at a community hospital cancer center.
Methods and Materials:
Between 2005 and 2009, 120 patients with early-stage breast cancer were being followed after treatment with accelerated partial breast irradiation brachytherapy using MammoSite, single or multilumen balloon, or Contura multilumen balloon. After their lumpectomy surgery, each patient was treated with Ir-192 high-dose rate unit following radiation therapy oncology group 0413 guidelines. The patients had multiple follow-ups at 6 months, 1 year, 2 years, 3 years, or more.
Results:
Based on the Harvard Breast Cosmesis Scale, 95.00% of patients described their cosmetic evaluation as the treated breast essentially the same as the opposite side (excellent) or minimal but identifiable effects were noticed from radiation (good). After a median follow-up of 36 months, the local recurrence rate was 1.66% and a disease-free survival is 98.3%. Forty-two patients reported 85 adverse events, which were fibrosis: 24.70%, hyperpigmentation: 20.00%, radiation skin reaction: 7.05%, seroma: 7.05%, breast pain: 7.05%, erythema: 5.88%, and other events were less than 5.00%. Of all the adverse events recorded, grade 1 to 3 events are 95.29% (n = 81), 2.35% (n = 2), and 2.35% (n = 2). There was no grade 4 or 5 events recorded.
Conclusions:
Our study has shown promising results for delivering radiation with MammoSite, single or multilumen balloon, or Contura multilumen balloon and has been successful in achieving local control in patients with early-stage breast cancer.
Introduction
Breast conservation therapy has become a standard treatment option for early-stage breast cancer with multiple trials showing similar survival long term to that of mastectomy. 1 Breast brachytherapy treatment is considered as an alternative option compared to whole breast radiation and is a possible choice if criteria are met for early-stage breast cancer. 1,2 Accelerated partial breast irradiation (APBI), especially APBI brachytherapy, shows increasing preference for patients in recent years than traditional whole breast irradiation due to the decrease in treatment time and better cosmesis. 1 For APBI brachytherapy, there are still many choices available, such as low-dose rate versus high-dose rate (HDR), difference devices (balloon types), difference sources (electrons vs photons), or timing (intraoperative vs after surgery). 3,4 Previous studies have been done extensively to cover the APBI brachytherapy simulation device selection and comparison, 5,6 treatment planning concerns, 7 -10 treatment toxicity, 11 -16 and clinical outcomes. 17 -28 However, with the increasing usage of APBI brachytherapy 1 and safety concerns 29,30 for brachytherapy, it is vital to have a single-community hospital experience, which will still be able to help the society to understand APBI brachytherapy treatment safety implementation, clinical outcomes, and help to confirm known results.
Our center has performed APBI brachytherapy using MammoSite (Hologic, Marlborough, Massachusetts), single or multilumen balloon, or Contura (SenoRx, Inc, Aliso Viejo, California) multilumen balloon in the past several years and have followed up the patients for a median of 36 months after their treatment. As of now multiple publications exist previously, 17 -28 but there is still opportunity to show a community hospital experience using combination of applicators, maintenance of quality assurance, and the clinical outcomes. Thus, the purposes of our study are to evaluate the efficacy of the APBI brachytherapy at our center with a combination of applicators and to evaluate the safety of the corresponding APBI brachytherapy. Our study will also focus on the disease-free survival, overall cosmetic outcome, adverse events, and local recurrence rates to determine whether results are comparable to other known studies.
Methods and Materials
Patient Selection
With the approval from the institutional review board, 120 patients with early-stage breast cancer were treated with APBI brachytherapy using MammoSite, single or multilumen balloon, or Contura multilumen balloon from April 2005 to October 2009 and was reviewed retrospectively. The institutional inclusion criteria for APBI were age >45, Tis, T1, T2, N0, M0 American Joint Committee Classification, having negative surgical margins, adequate skin spacing between the balloon surface and the surface of the skin (≥7mm). The exclusion criteria were patients who were pregnant or breast feeding, having an existing collagen-vascular disease, extensive intraductal component (Harvard Definition: >25% DCIS), or having infiltrating lobular histology.
Treatment Planning
The patients after their standard lumpectomy surgery with negative surgical margins would have the partial breast intracavitary applicator placed. The balloon of the APBI was placed with saline/contrast mixture to fill the cavity and remained for the duration of therapy. Each patient was then treated with Ir-192 HDR unit with a prescription of 340 cGy per fraction to 1 cm from the balloon surface for 10 fractions. This was done twice a day at least 6 hours apart. The treatment planning system is Oncentra Brachy (Nucletron, An ElektaCompany, version up to 4.3). Inverse planning simulated annealing optimization was used to achieve radiation therapy oncology group 0413 goals.
Follow-Up
Each patient was to follow-up at 6 months, 1 year, 2 year, and 3 years and more frequently at the discretion of the treating breast surgeon and the radiation oncologist. Baseline mammograms were obtained and cosmetic outcomes/cosmesis were document at each visit based on the Harvard Breast Cosmesis Scale. An excellent cosmetic result score was assigned when the treated breast looked essentially the same as the contralateral breast (as it relates to radiation effects). A good cosmetic score was assigned for minimal, but identifiable radiation effects on the breast that was treated. All adverse events related to balloon therapy were recorded and assessed for 2 conditions: severity and relationship to device. The Common Terminology Criteria for Adverse Events (CTCAE) guidelines were used for severity assignment.
Results and Discussions
The baseline patient and dosimetric characteristics for (n = 120) patients are provided in Table 1. The table shows that 83.33% (n = 100) were older than 61 years, the most common T stages were T1C (38.33%) with 76.66% having invasive cancer. A small portion of our patients had lymph node involvement (5%). According to the American Society for Radiation Oncology (ASTRO), our patients were categorized by patient demographics and tumor characteristics and were suitable, cautionary, or unsuitable. 2 Of our 120 patients involved in the study: 51.66% (n = 62) were suitable, 45% (n = 54) were cautionary, and .033 (n = 4) were unsuitable. 1 Of patients who were cautionary or unsuitable, 11 were T2, 20 were younger than <50 years, 6 had nodal involvement, 19 has Ductal Carcinoma in Situ (DCIS), and none were Breast Cancer genes 1 and 2 (BRCA) positive or received neoadjuvant therapy. A 4- to 5-cm sphere MammoSite device was the majority of devices used (90.83%) with another 5% using 4 × 6 cm2 sphere. The mean balloon volume at the time of brachytherapy was 50.58 cm and the depth of the device on computed tomography was 1.552 cm.
Baseline Patient and Dosimetric Characteristics.
Abbreviations: CT, computed tomography; N/A, not applicable.
Our study had a median follow-up of 36 months with the majority of our patients falling between 30 and 36 months. After 36 months of follow-up, 98.33% of our patients were disease free with 1.66% (n = 2) developing local recurrence. Of the 2 patients with local recurrences, one (stage: T2N0Mx; histopathologic grade: G1 well differentiated) was in the same breast, but a different quadrant. Since the breast was treated locally, it couldn’t have been avoided. The other patient (stage: T2NxMx; histopathologic grade: G3 poorly differentiated) had distant recurrence in the lung. The patient being older than 90 years at that time of treatment was at high risk with no chemotherapy due to the age, which may be contributed to distant recurrence. There was no significant difference between the ASTRO groups in tumor recurrence or survival. Based on the Common Terminology Criteria for Adverse Events, 42 patients experienced an adverse event or multiple events with the majority (97.6%) being either grade 1 or grade 2. Of the 85 events noted, fibrosis and hyperpigmentation were the most recorded event with a small portion developing erythema, seroma, or breast pain.
Figure 1 illustrates 6 different balloon brachytherapy trials that were conducted and followed up for at least 1 year. Our center achieved a 95% on the Harvard Cosmesis Scale for either excellent/good. This was comparable and in some cases even better than other studies with similar sample size.
Harvard Cosmesis Scale: excellent/good across multiple studies with at least 1 year follow-up.
Thirty five percent (n = 42) of our patients had an adverse event that was recorded, and the most common adverse events were recorded in Table 2. Figure 2 shows comparison of the adverse events of our data versus published data, when comparing common toxicities of brachytherapy to other centers. Our center has done very well, however, it is to be noted that each center may have different criteria for evaluation of toxicities and sample sizes were variable. Each of these centers followed up patients for greater than a year and reported their outcomes. In all, 17% of our patients experienced hyperpigmentation, 5% experienced seroma, and only 2.5% experienced telangiectasia. When comparing these results to other centers, our results showed very low adverse outcome in each category.
Clinical Follow-Up Outcomes.
Abbreviation: CTCAE, Common Terminology Criteria for Adverse Events.
Adverse events recorded across multiple studies using balloon therapy for at least 1 year.
Brachytherapy as an adjuvant treatment option is still relatively new compared to standards of whole breast radiation and data are still currently being collected to help analyze whether this is a viable option. A stratified ASTRO suitability study was done that analyzed the different categories (suitable, cautionary, and unsuitable) illustrated that external beam radiation therapy (EBRT) showed the lowest mastectomy risks versus lumpectomy alone while brachytherapy showed intermediate mastectomy risks versus lumpectomy alone. 2 However if only looking at the suitable category of patients, the absolute risk of mastectomy for EBRT versus brachytherapy was similar. 26 In older women with invasive breast cancer, EBRT showed a 78% relative benefit while brachytherapy showed a 39% relative benefit, but further studies need to be done which analyze the confounding factors that attributed to the benefit. 2 Multiple studies 11 -16 have shown toxicity effects after treatment. For example, fibrosis and hyperpigmentation are common adverse events after MammoSite APBI use and our results confirm those results. 3 Our results are comparable to other studies that have a minimum of 3-year follow-up in adverse events, cosmesis scale, and recurrence rates. Toxicity and adverse events are a result of skin dosing, balloon size, and technical skills, which can be improved with newer multicatheter applicators, stricter ASTRO classification, and enhanced catheter insertion techniques. Our study is limited by bias that includes a retrospective design, lack of standardization of surgical techniques, clinical follow-up, and adjuvant therapy.
Conclusions
Our study has shown promising results for delivering radiation with MammoSite, single or multilumen balloon, or Contura multilumen balloon and has been successful in achieving local control in patients with early-stage breast cancer. The study has also shown comparable to even better results to other studies in cosmetic outcome, adverse events, disease-free survival, and local recurrence rate.
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.