Applying Innovations in Surgical and Radiation Oncology to Breast Conservation Therapy

Guidelines by the AAPM and GEC-ESTRO on the use of innovative brachytherapy devices and applications: Report of Task Group 167

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used in the evaluation of innovative devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining the equivalence of the innovative treatment modality to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of innovative radiotherapy devices or applications is a critical part in which physicists should be actively involved. The physicist's role, along with physician colleagues, in this process is highlighted for innovative brachytherapy devices and applications and includes evaluation of (1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, (2) risks and benefits from a regulatory and safety perspective, and (3) resource assessment and preparedness. Further, it is suggested that any developed calibration methods be traceable to a primary standards dosimetry laboratory (PSDL) such as the National Institute of Standards and Technology in the U.S. or to other PSDLs located elsewhere such as in Europe. Clinical users should follow standards as approved by their country's regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the Accredited Dosimetry Calibration Laboratories in the U.S. is encouraged before a source is introduced into widespread routine clinical use. The American Association of Physicists in Medicine and the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) have developed guidelines for the safe and consistent application of brachytherapy using innovative devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of requirements of the U.S. Nuclear Regulatory Commission, U.S. Department of Transportation, International Electrotechnical Commission Medical Electrical Equipment Standard 60601, U.S. Food and Drug Administration, European Commission for CE Marking (Conformité Européenne), and institutional review boards and radiation safety committees.

Five-year outcome of patients classified in the "unsuitable" category using the American Society of Therapeutic Radiology and Oncology (ASTRO) Consensus Panel guidelines for the application of accelerated partial breast irradiation: an analysis of patients treated on the American Society of Breast Surgeons MammoSite® Registry trial

PURPOSE

We applied the ASTRO Consensus Panel (CP) guidelines for the application of accelerated partial breast irradiation (APBI) to patients treated with this technique on the ASBS MammoSite® registry trial to determine potential differences in outcome of patients classified in the "unsuitable" category.

METHODS

Of 1,449 cases treated with APBI on the registry trial, 176 fit the criteria for the unsuitable category: 130 cases were <50 years of age, 13 had positive margins, 38 had positive nodes, 6 had tumors >3 cm, and 9 had an EIC >3 cm. Rates of ipsilateral breast tumor recurrence (IBTR) and regional nodal failure (RNF) were assessed. Median follow-up was 53.6 months.

RESULTS

The 5-year actuarial rate of IBTR for unsuitable cases was 5.25% (RNF rate was 0.63%). By comparison, the 5-year actuarial IBTR rates for various subsets of patients were: all 1,449 cases, 3.89% (p = 0.2365); all 1,449 cases excluding unsuitable cases [n =1,273] (3.6%, p =0.1683); invasive only cases [n = 1,255] (3.86%, p = 0.2464); and invasive only cases excluding unsuitable invasive cases [n =1,105] (3.89%, p = 0.2396). On univariate analysis for variables potentially associated with IBTR in all 1,255 cases with invasive cancer (including age, tumor size, nodal status, overall stage, margin status, ER status, presence of an EIC, and ASTRO unsuitable category), only negative ER (-) status was associated with the 5-year rate of IBTR (p = 0002). No other variable (including unsuitable CP designation) was associated with IBTR.

CONCLUSIONS

The ASTRO CP guideline designation of unsuitable did not differentiate a subset of patients with a significantly worse rate of IBTR when treated with the MammoSite® breast brachytherapy catheter to deliver APBI.

Recommendations for research priorities in breast cancer by the coalition of cancer cooperative groups scientific leadership council: imaging and local therapy

Imaging and local therapy are important modalities for detection and management of localized breast cancer. Improvements in screening and local therapy have contributed to reduced breast cancer-associated morbidity and mortality. The Coalition of Cancer Cooperative Groups (CCCG) convened the Scientific Leadership Council (SLC) in breast cancer, an expert panel, to identify priorities for future research and current trials with greatest practice-changing potential. Panelists formed a consensus on research priorities for breast imaging and locoregional therapy, and also identified six trials judged to be of high priority. Current high priority trials included trials determining: (1) the role of accelerated partial breast versus whole-breast radiation (B39), (2) the feasibility, safety, and local and systemic control of small localized breast cancers treated with tumor ablation (Z1072), (3) the role of removal of the primary cancer in selected patients with metastatic disease (E2108), and (4) the clinical and biological effects of pre-operative anti-HER2-directed and ER-directed therapies in localized or locally advanced breast cancer (B41, Z1031, Z1041). Ongoing and future trials will further refine optimal locoregional management, and additional research is required to develop improved screening methods and identify high risk populations most likely to benefit from targeted screening.

Dosimetric Improvements in Balloon Based Brachytherapy Using the Contura® Multi-Lumen Balloon (MLB) Catheter to Deliver Accelerated Partial Breast Irradiation

Purpose

Preliminary dosimetric findings in patients managed with the Contura^® Multi-Lumen Balloon (MLB) breast brachytherapy catheter to deliver accelerated partial breast irradiation (APBI) on a multi-institutional phase IV registry trial were reviewed.

Material and methods

CT-based 3D planning with dose optimization was performed for all patients. For the study, new ideal dosimetric goals were developed: 1) ≥ 95% of the prescribed dose (PD) covering ≥ 90% of the target volume (TV), 2) a maximum skin dose ≤ 125% of the PD, 3) maximum rib dose ≤ 145% of the PD, and 4) the V150 ≤ 50 cc and V200 ≤ 10 cc. The frequency of concurrently achieving these dosimetric goals using the Contura^® MLB was investigated.

Results

194 cases were evaluable. Employing the MLB, all ideal dosimetric criteria were achieved in 76% of cases. Evaluating dosimetric criteria separately, 90% and 89% of cases met the new ideal skin and rib dose criteria, respectively. In 96%, ideal TV coverage goals were achieved and in 96%, dose homogeneity criteria (V150 and V200) were met. For skin spacing ≥ 5-7 mm, the median skin dose was 121% of the PD and when < 5 mm, the median skin dose was 124.4%. For rib distancees < 5 mm, the median rib dose was reduced to 136.4% of the PD. For skin spacing < 7 mm and distance to rib < 5 mm, the median skin and rib doses were concurrently limited to 121% and 142.8% of the PD, respectively.

Conclusions

The Contura^® MLB catheter provides potential improvements in dosimetric capabilities (i.e., reduced skin and rib doses and improved TV coverage) in many clinical scenarios.

Initial surgical experience evaluating early tolerance and toxicities in patients undergoing accelerated partial breast irradiation using the Contura Multi Lumen Balloon breast brachytherapy catheter

We reviewed our surgical experience with the Contura Multi Lumen Balloon breast brachytherapy catheter used to deliver accelerated partial breast irradiation and determined short-term treatment efficacy, cosmesis, and toxicity. Forty-six patients undergoing breast conserving therapy, including the use of Contura catheter, were analyzed. Thirty-four Gray were delivered in 10 fractions. Fourteen patients had stage 0, 24 had stage I, and 8 had stage II breast cancer. Catheters were placed with a closed cavity technique. Median minimum skin spacing was 10 mm (range, 2-18 mm). Median maximum skin doses were 99.7 per cent of the prescription dose. Nine patients were treated with a skin spacing < or = 5 mm (2 patients with 2 mm skin spacing). The percentage of patients with excellent/good cosmesis at 6 (n = 26) and 12 (n = 13) months was 100 per cent, respectively. Patient tolerance was assessed on a scale of 0-10 (0 = no pain, 10 = requiring narcotic analgesics). Pain was graded < or = 3 in 98 per cent of patients at catheter insertion and 84 per cent at catheter removal. Four breast infections (8.8%) and one symptomatic seroma developed. Adjuvant accelerated partial breast irradiation using the Contura Multi Lumen Balloon exhibited similar toxicities to standard single lumen, single dwell balloon brachytherapy with improvements in dosimetric capabilities allowing the treatment of patients with skin spacing < or = 5 mm.

Phase I/II study evaluating early tolerance in breast cancer patients undergoing accelerated partial breast irradiation treated with the mammosite balloon breast brachytherapy catheter using a 2-day dose schedule

PURPOSE

Initial Phase I/II results using balloon brachytherapy to deliver accelerated partial breast irradiation (APBI) in 2 days in patients with early-stage breast cancer are presented.

MATERIALS AND METHODS

Between March 2004 and August 2007, 45 patients received adjuvant radiation therapy after lumpectomy with balloon brachytherapy in a Phase I/II trial delivering 2800 cGy in four fractions of 700 cGy. Toxicities were evaluated using the National Cancer Institute Common Toxicity Criteria for Adverse Events v3.0 scale and cosmesis was documented at >or=6 months.

RESULTS

The median age was 66 years (range, 48-83) and median skin spacing was 12 mm (range, 8-24). The median follow-up was 11.4 months (5.4-48 months) with 21 patients (47%) followed >or=1 year, 11 (24%) >or=2 years, and 7 (16%) >or=3 years. At <6 months (n = 45), Grade II toxicity rates were 9% radiation dermatitis, 13% breast pain, 2% edema, and 2% hyperpigmentation. Grade III breast pain was reported in 13% (n = 6). At >or=6 months (n = 43), Grade II toxicity rates were: 2% radiation dermatitis, 2% induration, and 2% hypopigmentation. Grade III breast pain was reported in 2%. Infection was 13% (n = 6) at <6 months and 5% (n = 2) at >or=6 months. Persistent seroma >or=6 months was 30% (n = 13). Fat necrosis developed in 4 cases (2 symptomatic). Rib fractures were seen in 4% (n = 2). Cosmesis was good/excellent in 96% of cases.

CONCLUSIONS

Treatment with balloon brachytherapy using a 2-day dose schedule resulted acceptable rates of Grade II/III chronic toxicity rates and similar cosmetic results observed with a standard 5-day accelerated partial breast irradiation schedule.

Initial radiation experience evaluating early tolerance and toxicities in patients undergoing accelerated partial breast irradiation using the Contura Multi-Lumen Balloon breast brachytherapy catheter

PURPOSE

We reviewed our institution's experience treating patients with the Contura Multi-Lumen Balloon (SenoRx, Inc., Irvine, CA) breast brachytherapy catheter to deliver accelerated partial breast irradiation.

METHODS AND MATERIALS

Forty-one patients treated with breast-conserving therapy received adjuvant radiation using the Contura catheter (34Gy in 3.4Gy fractions). Thirteen patients had Stage 0, 21 had Stage I, and 7 had Stage II breast cancer. Median followup was 8 months (range, 1-17).

RESULTS

Median, minimum skin spacing was 10mm (range, 2-17). Median, maximum skin doses (% of prescribed dose [PD]) were 99.7 (range, 57.1-124.1). Eight patients were treated with a skin spacing <or=5mm and 2 had a spacing of 2mm. Median, maximum rib doses were 102.6% of PD (10.0-187.7), and the median percentage of the planning target volume for evaluation (PTV_EVAL) receiving 95% of the PD was 98.8 (range, 79.4-107.4). The median volume receiving 200% of the PD was 5.7cc (range, 1.3-9.9). The percentage of patients with excellent/good cosmetic results at 6 months (n=15) and 12 months (n=12) was 100%. Patient tolerance was assessed on a scale 0-10 (0=no pain, 10=requiring narcotic analgesics). In 37 out of 38 patients, pain was graded <or=3 at the time of catheter insertion. Four breast infections (11%) and one transient symptomatic seroma (3%) developed.

CONCLUSION

Adjuvant accelerated partial breast irradiation using the Contura Multi-Lumen Balloon catheter exhibited similar toxicities to standard single lumen balloon brachytherapy with improvements in dosimetric capabilities (i.e., reduced skin and rib doses and improved PTV_EVAL coverage).

Growth laws in cancer: implications for radiotherapy

Comparing the conventional Gompertz tumor growth law (GL) with the "Universal" law (UL), which has recently been proposed and applied to cancer, we have investigated the implications of the growth laws for various radiotherapy regimens. According to the GL, the surviving tumor cell fraction could be reduced ad libitum, independent of the initial tumor mass, simply by increasing the number of treatments. In contrast, if tumor growth dynamics follows the Universal scaling law, there is a lower limit of the surviving fraction that cannot be reduced further regardless of the total number of treatments. This finding can explain the so-called tumor size effect and re-emphasizes the importance of early diagnosis because it implies that radiotherapy may be successful provided that the tumor mass at treatment onset is rather small. Taken together with our previous work, the implications of these findings include revisiting standard radiotherapy regimens and treatment protocols overall.