Factors Associated With Chest Wall Toxicity After Accelerated Partial Breast Irradiation Using High-Dose-Rate Brachytherapy

Dosimetric analysis of breast cancer tumor bed boost: An interstitial brachytherapy vs. external beam radiation therapy comparison for deeply seated tumors

PURPOSE

To dosimetrically compare interstitial brachytherapy (MIBT) vs. EBRT (3DCRT and high-energy electron beams) for deep-seated tumor bed boosts (depth ≥4 cm) in early-stage breast cancer.

METHODS AND MATERIALS

Planning CTs of fifteen left-side breast cancer patients previously treated with MIBT boost chosen for this study. MIBT, 3DCRT (three-field technique), and enface high-energy electron (15-18 MeV) plans retrospectively generated on these images. To minimize intrapatient target contour inconsistency, due to a technical limitation for transferring identical contours from brachytherapy to EBRT planning system, spherical volumes delineated as hypothetical CTVs (CTV-H) (depth ≥4 cm with considering the geometry of the brachytherapy implant) instead of original lumpectomy cavities (which had irregular contours). In EBRT, PTV-H=CTV-H+5 mm. To account for beam penumbra, additional PTV-H to beam-edge margins added (3DCRT = 5 mm; electron = 10 mm). Included organs at risk (OARs) were ipsilateral breast, skin, ribs, lung, and heart. Prescribed dose-fractionations were 12 Gy/3fractions (MIBT) and 16 Gy/8fractions (EBRT) (BED = 24 Gy, breast cancer Alpha/Beta = 4 Gy). Biologically equivalent DVH parameters for all techniques compared.

RESULTS

Mean CTV-H depth was 6 cm. Normal breast V_25%-V_100%; skin V_10%-V_90%; rib V_25%-V_75%; lung V_5%-V_25%; heart V_10%; mean lung dose; ribs/lung D_max were lower in MIBT vs. 3CDRT. MIBT reduced breast V_25%-V_125%; skin V_25%-V_125%; rib V_25%-V_75% and V_100%; lung V_25%-V_90%; heart V_10%-V_50%; skin/ribs/lung D_max compared to electrons. In contrast, breast V_125%-V_250% and V_175%-V_250% were increased in MIBT vs. 3DCRT and electron plans, respectively. Electron plans had the minimum mean heart dose.

CONCLUSIONS

From a dosimetric point of view, in deeply-seated lumpectomy beds, MIBT boost better protects OARs from exposure to medium and high doses of radiation compared to 3DCRT and high energy electron beams (except more ipsilateral breast hot spots).

Clinical implementation of a novel Double-Balloon single-entry breast brachytherapy applicator

PURPOSE

The purpose of the study was to describe the clinical utilization of a novel Double-Balloon applicator for accelerated partial breast irradiation (APBI).

METHODS AND MATERIALS

The Double-Balloon single-entry breast applicator contains a single central treatment catheter, as well as four peripheral catheters that can be differentially loaded to customize radiation dose coverage. An inner balloon is filled with up to 7-30 cm³ of saline to increase separation between the peripheral catheters, and an outer balloon is filled with up to 37-115 cm³ of saline to displace breast tissue from the peripheral catheters. Treatment planning objectives include coverage of the breast planning target volume to a minimum of V₉₀ > 90%, limiting dose heterogeneity such that V₂₀₀ < 10 cm³ and V₁₅₀ < 50 cm³, and limiting maximum dose to skin (<100% of prescription dose) and ribs (<145% of prescription dose).

RESULTS

High-dose-rate APBI was delivered to 11 women using this device (34 Gy in 10 twice daily fractions). The mean V₉₀ was 98.2% (range 94.2-99.4%). The mean skin D_max with the Double-Balloon applicator was 83.3% (range 75.6-99.5%). The mean breast V₂₀₀ was 5.8 cm³ (range 2.3-10.2 cm³), and the mean breast V₁₅₀ was 32.9 cm³ (range 25.0-41.7 cm³). Pretreatment quality assurance was performed using CT prior to each morning fraction and ultrasound prior to each afternoon fraction.

CONCLUSIONS

The Double-Balloon applicator can be easily introduced into a previously existing brachytherapy program. APBI plans created with this applicator achieve excellent planning target volume coverage, while limiting skin dose and maintaining breast V₂₀₀ < 10 cm³.

A Single-Site Retrospective, Nonrandomized Study of Accelerated Partial Breast Irradiation Brachytherapy for Early-Stage Breast Cancer Treatment to Evaluate Local Tumor Control, Cosmetic Outcome, and Toxicities

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.