Standard Tangential Fields Research Articles

Radiotherapy instead of axillary lymph node dissection: evaluation of axillary lymph node dose coverage with whole breast radiotherapy.

BackgroundThe purpose of this study was to investigate the dose coverage of sentinel lymph nodes (SLN), level I, II and III axillary volumes from tangent fields for breast cancer patients with positive SLN without axillary dissection.Materials and methodsIn 30 patients with cN0 invasive breast cancer treated with breast conserving surgery and SLN biopsy, the SLN area was intraoperatively marked with a titanium clip. Retrospectively, the SLN area and axillary target volumes were contoured, and three plans [standard tangent fields (STgF), high tangent fields (HTgF), and STgF + axillary-supraclavicular field] were generated for each patient. The prescribed dose was standardized to 50 Gy in 2 Gy fractions to the isocenter.ResultsThe mean dose with STgF or HTgF was 33.1 and 49.1 Gy (p = 0.0001) in the SLN area, 25.7 and 45.1 Gy (p < 0.0001) in the volume of level I, 7.2 and 28.9 Gy (p < 0.0001) in the level II and 3.5 and 12.7 Gy (p = 0.0003) in the level III. Adequate therapeutic doses to the level II or III volumes were delivered only with STgF + axillary-supraclavicular field. The mean dose of ipsilateral lung was the highest with the three-field-technique, 9.9 Gy. SLN area, level I, II or III were completely included in the HTgF with 93.3%, 73.3%, 13.3% and 0%, respectively.ConclusionsSLN area should be marked by surgical clip and axillary target volumes should be contoured to obtain accurate dose estimations. The use of HTgF improve axillary coverage.

Contralateral breast dose with electronic compensators and conventional tangential fields – A clinical dosimetric study

Dose to the contralateral breast (CLB) from radiotherapy treatment has the potential to induce secondary breast cancer. Electronic tissue compensation (eComp) for breast cancer patients is one of the alternative methods to conventional 3D-conformal radiotherapy that eliminates the use of wedges. Several studies have investigated dose to the CLB using tangential fields involving wedges, intensity-modulated radiation therapy and volumetric modulated arc radiation therapy and various other techniques via treatment planning system calculations, Monte Carlo methods and phantoms. However, there are limited data published in assessing the actual dose received by the CLB from treatment with eComp-based tangential fields.In this study, the CLB dose for patients undergoing tangential field radiotherapy with eComp and enhanced dynamic wedged (standard) tangential fields was measured and compared to assess the CLB dose between the two methods. Measurements were conducted on a randomised trial of 40 patients, 20 of them had undergone standard planning, and the remaining 20 were treated with eComp. The mean surface dose measured with TLDs at 3cm from the medial tangential border for eComp and standard techniques was 10.04±1.37% and 10.14±2.05%, respectively for a prescription dose of 2.65Gy/fraction. The estimated dose at 1cm depth in tissue, measured with the use of perspex domes placed over the TLD at the same location, was 5.12±0.87% and 6.29±2.01% for eComp and standard, respectively.The CLB dose is dependent on the proximity of the medial tangential field edge to the contralateral breast and is patient-specific. The results of this study show that at 1cm depth, eComp technique delivers significantly less dose (p<0.05) to the CLB as compared to standard tangential fields. Furthermore, the surface dose measured for both eComp and standard are comparable indicating that the eComp-based tangential field technique does not contribute any excess dose to CLB when compared to standard tangential fields. The excess relative risk (ERR) for radiation-induced cancers for eComp was found to be 0.08, compared to 0.11 for standard tangential fields.

Variability of Medial and Lateral Borders Delineation in Guidelines for Post-Mastectomy Irradiation Significantly Affects Radiation Dose Received by Left Lung and Heart

Background: Delineation of Clinical Target Volume (CTV) is a basic step in 3 Dimensional Conformal (3DCRT). A notable variation however exists among different guidelines in delineation of chest wall (CW) CTV specially for the lateral margin. Some authors used wire localization for the anatomical insertion of the presumed breast It is expected that lateral margin delineation will affect the standard tangential fields and therefore the ipsilateral lung &amp; heart (in left side) volumes irradiated to high dose. Aim of work: Evaluation of the effect of using various guidelines for chest wall CTV delineation on outcome regarding doses received by heart and left lung (in post left mastectomy irradiation) and compare these outcomes to that of wire based delineation (WBD). Methodology: Ten patients with T3/4 &amp;/or N+ left breast cancer were planned for post mastectomy CW-3DCRT. Delineation of CW by one radiation oncologist followed 2 different guidelines namely RTOG &amp; ESTRO in addition to a 3rd anatomical based wire delineation of chest wall underlying the presumed breast. Three CRT plans for the 3 CTVs were compared regarding coverage, homogenity &amp; toxic dose to heart &amp; lt. lung. Results: CTV was a highly significantly smaller when delineated using WBD vs RTOG or ESTRO guidelines. There was no statistically significant difference between the 3 delineated volumes regarding coverage &amp; homogeneity parameters. A highly statistically significant better (lesser) V20Gy &amp; V30Gy received by lt. lung for plans based on WBD (16.0 +/- 4.1% &amp;12.75 +/- 2% respectively) vs those based on ESTRO (19.1 +/- 1.73 &amp; 15.2 +/- 5.1 respectively) or RTOG guidelines (18.22 ± 1.6 &amp; 14.52 ± 5.3 respectively), p=0.001 for V20Gy &amp; 0.01 for V30Gy. For cardiac dose, a statistically significant lower D50% received by the heart in plans based on WBM delineation (101.6 ± 41.2 Gy) compared to plans based on ESTRO &amp; RTOG guidelines based CTV (141 +/- 81cGy &amp; 132 +/- 93 cGy respectively, p= 0-00001). Conclusion: WBD of post lt. mastectomy chest wall CTV delineation significantly reduced toxic dose received by heart &amp; lt. lung. Larger trial with clinical follow up to test for being not inferior to ESMO &amp;/or ESRTO guidelines based treatment regarding local recurrence.

Acute toxicity outcomes and dosimetric implications from incidental irradiation of adjacent tissues in tangent field hypofractionated breast radiotherapy.

Adjacent tissues-in-beam (TIB) may receive substantial incidental doses within standard tangent fields during hypofractioned whole breast irradiation (HF-WBI). To characterize the impact of dose to TIB, we analyzed dosimetric parameters of TIB and associated acute toxicity. Plans prescribed to 40.5 Gy/15 fractions from 4/2016-1/2018 were evaluated. Structures of interest were contoured: (1) TIB: all tissues encompassed by plan 30% isodose lines, (2) breast, (3) non-breast TIB (nTIB): TIB minus contoured breast. Volumes of TIB, breast, and nTIB receiving 100%-107% of prescription dose (V100-V107) were calculated. Twelve patient- and physician-reported acute toxicities were prospectively collected weekly. Correlations between volumetric and dosimetric parameters were assessed. Uni- and multivariable logistic regressions evaluated toxicity grade changes as a function of TIB, breast, and nTIB V100-V107 (in cm3). We evaluated 137 plans. Breast volume was positively correlated with nTIB and nTIB V100 (rho = 0.52, rho = 0.30, respectively, both p < 0.001). V107 > 2 cm3 were noted in 14% of breast and 21% of nTIB volumes. On multivariable analyses, increasing breast and nTIB V100 significantly raised odds of grade 2+ dermatitis and burning/twinging pain, respectively; increasing nTIB V105 elevated odds of hyperpigmentation and burning pain; and increasing nTIB V107 raised odds of burning pain. Threshold volumes for >6-fold odds of developing burning pain were TIB V105 > 100 cm3 and V107 > 5 cm3. For HF-WBI, doses to nTIB over the prescription predicted acute toxicities independent of breast doses. These data support inclusion of TIB as a region of interest in treatment planning and protocol design.

SPECT-CT localization of axillary sentinel lymph nodes for radiotherapy of early breast cancer.

To evaluate the opportunities of single photon emission tomography/computerized tomography (SPECT-CT) for localization of axillary sentinel lymph nodes (ASLNs) and subsequent radiotherapy planning in women with early breast cancer. Individual topography of ASLN was determined in 151 women with clinical T1-2N0M0 breast cancer. SPECT-CT visualization of ASLNs was initiated 120min after intra-peritumoral injection of 99mTc-radiocolloids. Doses absorbed by virtual ASLNs after the whole breast irradiation with standard and extended tangential fields were calculated on a treatment planning station. SPECT-CT demonstrated a large variability of ASLN localization. They were detected in the central subgroup in 94 (61%) patients, in pectoral - in 77 (51%), and in interpectoral - in 4 (3%) patients. Sentinel lymph nodes "lying on the chest" were revealed in 35 (23%) cases.We found that with standard tangential fields coverage of ASLNs was obtained only in 20% of evaluated women. Extended tangential fields can effectively irradiate ASLNs localized in all axillary sub-regions with the exception of ASLNs "lying on the chest". SPECT-CT mapping of ASLNs in women with cT1-2N0M0 breast cancer reveals their variable localization. This information can be important for planning of radiation treatment in women that underwent breast conserving surgery without an axillary surgery.

Standard Tangential Radiation Fields Do Not Provide Incidental Coverage to the Internal Mammary Nodes

PurposeThe purpose of the study was to evaluate the incidental dose delivered to the internal mammary nodes (IMNs) in patients treated with tangential 3-dimensional conformal radiation therapy and to identify potential parameters that may affect the IMN mean dose. Methods and MaterialsThe study cohort consisted of 362 consecutively treated patients with breast cancer in our center between January 2015 and July 2017 who had received adjuvant whole-breast radiation therapy or postmastectomy radiation with or without a supraclavicular ± axillary field and without intentional inclusion of the IMN chain. The clinical target volume (CTV) for the IMNs was contoured per the Radiation Therapy Oncology Group 3509/3510 protocol and was then divided into 3 subregions: upper, mid, and lower thirds. The planning target volume for the IMNs was generated by adding 5 mm to the CTV. The primary endpoint was to assess the V40 (volume receiving 40 Gy) to the IMN planning target volume and its potential influencing parameters using a linear regression model. ResultsThe mean (±standard deviation) dose to the CTV IMN chain was 36% ± 28.7%. The Kruskal–Wallis test demonstrated significant differences in the median dose delivered to each level: upper third (7.2%), mid third (21.5%), and lower third (41.7%) (P < .001). The mean V40 IMN planning target volume was 14.2% (standard deviation, 18.7%). Presternal fat thickness (regression coefficient [RC] = –16.4; P < .001), postmastectomy radiation (RC = 24; P < .001), reconstruction after mastectomy (RC = –22.4; P < .001), and the addition of a supraclavicular field (RC = 8.8; P = .03) were all significantly associated with IMN mean dose. ConclusionsFor patients receiving standard breast/chest wall tangential radiation fields, the IMN chain is not incidentally covered with therapeutic doses in the vast majority of cases. Therefore, if regional nodal radiation is intended to include the IMNs, contouring and careful plan review are necessary to ensure adequate therapeutic coverage.

Location of Recurrence in Women Treated with Conventionally Planned Whole Breast Radiotherapy

Whole breast radiotherapy (RT) following breast-conserving therapy is known to reduce local recurrence in early-stage breast cancer. Conventionally, the external palpable breast has been used as the clinical target volume (CTV). In the era of CT simulation/planning, post-operative tumour bed (cavity) localization is also important as it is a high risk area of local recurrence. This study evaluates the location of the tumour bed cavity and its relationship to the area of recurrence in women previously treated with whole breast RT without explicit delineation of the cavity. A consecutive sample of 50 women with breast tumours (Tis-T3,Nx-1) previously treated with whole breast RT+/-boost was identified. The planning CTV was based on patient's palpable breast wired with radio-opaque markers during CT simulation and treated to a minimum of 92% prescription dose (50Gy-25fx or 40/42.4Gy-16fx) using forward planned intensity modulated RT (IMRT). The tumour bed was retrospectively contoured and expanded by 10mm (excluding skin and lung) for the planning target volume (cPTV). Geographic miss was defined as any part of the target volume receiving <50% of the prescription dose (D50). Five-year follow-up and the location for local and/or distant recurrence were collected. Descriptive statistics and unpaired Student's t-tests were performed, p-values <0.05 were considered as statistically significant. Five (10%) women had geographic miss to the cavity contours (CAVmiss). Women with CAVmiss had cavities located in extreme aspects of the breast: lateral (3); medial (1); or superior (1). The median follow-up was 4.5years and time to failure was 3.5years (1 to 5 years). Within the CAVin cohort (45), 2 (6%) patients recurred locally within the ipsilateral breast (1-year and 3-year follow-up, respectively); 1 (3%) patient developed regional disease to the infraclavicular lymph nodes at 4-year follow-up, and 1 (3%) developed contralateral inflammatory breast disease at 4-year follow-up; 11 patients were lost to follow-up. Of the 5 women with CAVmiss: 1 developed local recurrence at the edge of the original fields near the tumour bed and regional disease to the axilla and supraclavicular nodal basins (4yr follow-up); 1 developed distance disease (3yr follow-up). Local recurrence can occur near the tumour bed following whole breast RT. Without delineation of the post-operative cavity, 10% of women had inadequate coverage to their tumor bed despite the use of standard tangential RT fields. The adoption of cavity delineation would reduce the risk of geographic miss and ensure the accuracy of radiotherapy.

The State of Surgical Axillary Management and Adjuvant Radiotherapy for Early-stage Invasive Breast Cancer in the Modern Era

BackgroundFor clinical T1-2N0 breast cancer, sentinel lymph node biopsy (SLNB) has been shown in American College of Surgeons Oncology Group (ACOSOG) Z0011 to be sufficient for women with 1 to 2 positive sentinel lymph nodes with no added benefit for completion axillary lymph node dissection (ALND). Z0011 specified whole breast radiotherapy (RT) using standard tangential fields; however, later analysis showed variation in field design. We assessed nationwide practice patterns and examined factors associated with patients undergoing completion ALND and subsequent radiation field design. Patients and MethodsWomen with clinical T1-2N0 breast cancer who underwent breast-conserving surgery, axillary staging, and whole breast RT in 2012 to 2013 were identified in the National Cancer Database. Multivariable logistic regression modeling was used to examine axillary management and RT, adjusting for demographic and clinicopathologic factors. ResultsAmong 83,555 patients meeting criteria, 9.3% underwent upfront ALND, 75.8% underwent SLNB only, and 14.9% underwent SLNB with completion ALND. From 2012 to 2013, upfront SLNB increased from 90.1% to 91.4% (odds ratio, 1.14; P < .001). Among 9474 patients that underwent SLNB with 1 to 2 positive sentinel nodes, 31.2% received completion ALND. Among patients with 1 to 2 positive sentinel nodes, SLNB increased from 65.8% to 72.1% from 2012 to 2013 (P < .001). For patients with 1 to 2 positive lymph nodes that underwent SLNB only, 63.4% underwent breast RT, whereas 36.6% received breast and nodal RT. ConclusionsNationwide practice patterns of axillary management vary. Despite an increasing rate of SLNB, many patients still receive upfront and completion ALND. Furthermore, there is significant variation in RT field design, and modern treatment guidelines are warranted for this patient population.

Clinical implementation of IMRT step and shoot with simultaneous integrated boost for breast cancer: A dosimetric comparison of planning techniques

Purpose: Radiotherapy post-lumpectomy with two coplanar tangent beams is the standard treatment for women with early stage breast cancer. Despite the use of wedges as tissue compensators, the resultant plans often contains a significant dose gradient and 'hot spots' in excess of 15% or more of prescribed dose. In recent years a field-in-field (FIF) dose-compensation technique, which use two standard tangent fields and one or two (rarely three) small beams within these, was developed. It allows to obtain a more uniform dose throughout the target volume in the majority of cases but not in all. This study presents our experience to develop optimal intensity modulated radiation therapy (IMRT) techniques to be applied clinically in those cases where the traditional technique with two tangent fields or its variant field in field (FIF) are unable to achieve a satisfactory planning target volumes (PTVs) coverage and dose objectives to the organs at risk (OARs). Methods: We investigated two pure IMRT plans (named 3F-IMRT and 4F-IMRT) and a hybrid one (H-IMRT). Treatment plans were performed for 7 left-sided and 4 right-sided breasts using simultaneously integrated boost (SIB) planned technique with inverse optimization. Results were compared with those obtained with FIF technique. Dose prescribed was 45 Gy/20 fractions to the breast and 50 Gy /20 fractions to the lumpectomy cavity delivered in 5 fr/week. Dose–volume histograms were generated and parameters as target dose coverage, conformity and homogeneity as well as OARs dose distribution were analyzed. Finally the secondary cancer risk to contralateral breast due to radiation was evaluated as a further parameter for the choice of the optimal plan. Results: Compared to the FIF, the three IMRT plans provided the same target coverage and a better dose conformation, but a worst dose homogeneity of the boost target. The volume of the OARs, receiving higher doses than 15 Gy was reduced but was increased the volume receiving low doses. This causes the increase of the risk of radiation induced cancer, especially for the contralateral breast. For this organ, the highest value of the excess absolute risk (EAR) was associated to the 4F-IMRT, while the lower, to the FIF. Conclusion: The intensity-modulated radiation therapy techniques 5F-IMRT and 4F-IMRT were the best to be applied clinically in those cases, where the traditional technique of irradiation of the breast is unable to achieve the PTVs coverage and dose objectives to the OARs. However, all the IMRT techniques showed an increased volume of healthy tissues receiving low doses, so they should not be used in extensive manner and in particular should be avoided in the cases of young women due to the excess of risk to develop a secondary cancer.

Dosimetric evaluation of volumetric modulated arc therapy for bilateral breast carcinoma

Introduction Patients with bilateral breast carcinoma are usually treated with two sets of tangential beams with different iso-centers. Single iso-center Volumetric Arc Therapy (VMAT) treatment plan can give several logistical advantages, avoiding also the overlapping of tangential fields. Purpose Perform a dosimetric study to evaluate the enforcement of Volumetric Modulated Arc Therapy (VMAT) on bilateral breast carcinoma radiotherapy. Materials and methods Treatment plans for 5 patients, previously treated with 50.4 Gy/28 fractions, using 3D Conformal Radiotherapy planned with a standard tangential field technique, were replanned with VMAT technique. The PTV used in the optimization was expanded 2 cm to the external direction, in order to correct respiratory movement. VMAT plans were optimized with 2-arcs, 3-arcs and 4-arcs, all plans using one iso-center, avoiding angles between 140° and 220°. Results VMAT presents evident logistical advantages for bilateral breast treatment; one iso-center reduces patient setup time, and treatment time. 4-arcs plan and 3-arcs plan had similar dosimetric results, being 2-arcs plan the worst solution. Comparing to the standard tangential field technique, VMAT had better PTV dose coverage (Conformity Index improved in a 13%), avoiding hotspots, which can appear on 3DCRT standard tangential field technique. VMAT also reduces high doses to OARs. On the other hand, VMAT increase lower doses to the whole body, increasing slightly the mean heart dose. Conclusion VMAT technique showed logistical advantages for the treatment of bilateral breast carcinoma, but also dosimetric improvements. 3DCRT had greater high doses to OARs, but save lower doses to the whole body.

Abstract P3-12-06: Active breathing control in the management of left-sided breast cancer with irradiation: A dosimetric analysis of cardiac and lung dose

Abstract Purpose: Deep inspiratory breath hold (DIBH) is a technique that has been increasingly utilized over the past several years for the purpose of reducing the radiation dose received by the heart and ipsilateral lung during radiotherapy (RT) for breast cancer. The purpose of this study was to provide a comparative analysis of cardiac and lung dose in patients treated with and without moderate DIBH with an active breathing control (ABC) device during RT for left-sided breast cancer at a community radiation oncology center. Methods: From June 2013 to December 2014, 83 patients with stages 0-III left-sided breast cancer were treated with RT. Of these, 45 patients underwent CT simulation with an ABC device and the remaining 38 patients underwent standard free-breathing CT simulation for RT planning. Twenty-eight patients in the ABC cohort were treated with standard tangent fields and 18 were treated with locoregional RT. The non-ABC cohort included 26 patients treated with standard tangents and 12 treated with locoregional RT. A 4- or 5-field technique was utilized in all locally advanced patients to allow for coverage of the supraclavicular fossa and internal mammary lymph nodes with inclusion of low axillary coverage based on individual risk factors. All patients were treated with 3D-conformal techniques utilizing multi-leaf collimators to block the heart. Comparisons were made between mean heart dose, heart V5, mean lung dose, and lung V5 with and without the use of ABC. Kruskal-Wallis tests were used to determine significance between groups with α for significance set at p ≤0.05. Results: On combined analysis, the use of DIBH with ABC resulted in a reduction in heart V5 (1.5 versus 5.4%; p=0.018). Mean heart dose, mean lung dose, and lung V5 were not significantly improved with the use of ABC. On subgroup analysis, patients treated with locoregional RT had reduced mean heart dose (161 cGy versus 309 cGy; p=0.014) and heart V5 (2.3% versus 14.8%; p&amp;lt;0.001) compared to patients treated with a standard free-breathing technique. Conclusions: The use of ABC provided a significant reduction in heart V5 in all patients with left-sided breast cancer and in mean heart dose and heart V5 in patients treated with locoregional RT. This retrospective, single-institution analysis demonstrates the feasibility of implementing moderate DIBH with ABC technology in the treatment of left-sided breast cancer in a community radiation oncology center. Citation Format: Gogineni ES, Kehrer JD, Jones GC, Premo C, Stinson S. Active breathing control in the management of left-sided breast cancer with irradiation: A dosimetric analysis of cardiac and lung dose. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-12-06.

Comparison of standard tangential field and multiple fileld radiotherapy in axillary lymph node after conserving surgery

Objective To investigate the difference of standard tangential field and multiple fileld radiotherapy in axillary lymph node after conserving surgery, to provide a reference for clinical treatment. Methods 20 cases of left breast cancer patients were selected, all patients underwent breast-conserving surgery, postoperative radiotherapy.All patients used standard radiotherapy wild tangent based and reverse-intensity modulated radiation therapy optimization.Armpit I, Ⅱ lymph nodes were used to calculate the extent of coverage of the original plan, target dose uniformity HI, dose conformal CI, dosimetric parameters were calculated. Results Under standard tangential field irradiation, I stand mean dose was (33.95 ± 8.24)Gy, which was significantly higher than Ⅱ station (22.13±6.67)Gy, and V50, V45, V40 were (22.45±6.32)%, (39.83±7.54)%, (49.65±8.31)%, which were higher than Ⅱ stand, I stand irradiation was significantly more, the differences were statistically significant (t=5.632, P=0.009; t=7.214, P=0.000; t=8.954, P=0.000; t=6.121, P=0.002). The whole breast irradiation armpit IMRT plan, 19 patients (95.00%) reached 95% by volume APTV≥50Gy, coverage was better; but HI, CI were (1.11±0.03), (1.36±0.07) respectively, which were significantly worse than the standard wild tangent, the differences were statistically significant (t=6.584, P=0.001; t=9.144, P=0.000). Under Hatano IMRT irradiation ipsilateral lung, heart suffered an average dose of (1 694.58±102.31)cGy, (645.54±74.44)cGy, which were significantly more than the standard tangential field irradiation, the differences were statistically significant (t=7.654, P=0.000; t=6.654, P=0.001). Conclusion Standard tangential field irradiation has poor coverage in Ⅱ axillary lymph node station, irradiation intensity modulated radiation has better coverage, but significantly increased the dose to normal tissues. Key words: Breast-conserving surgery; Axillary lymph nodes; Radiotherapy; Dose

Once-Weekly Hypofractionated Whole-Breast Radiotherapy After Breast-Conserving Surgery in Older Patients: A Potential Alternative Treatment Schedule to Daily 3-Week Hypofractionation

BackgroundThe purpose of this study was to retrospectively report clinical outcomes on a consecutive series of older early breast cancer patients treated with once-weekly adjuvant whole-breast radiation therapy (WBRT) after breast-conserving surgery (BCS). Patients and MethodsA total of 291 patients (298 breasts) were treated with WBRT between 2007 and 2013. Patients were given 6 to 6.5 Gy in 5 weekly fractions (total dose, 32.5-30 Gy) over 5 weeks. Clinical end points were local control (LC), disease-free (DFS), cancer-specific (CSS), and overall survival (OS), and acute and late toxicity and cosmesis. Prognostic clinical variables were assessed with respect to DFS. ResultsMedian follow-up was 46.5 months (range, 12-84 months). The 3- and 5-year LC rates were 99.5% (95% confidence interval [CI], 96.4-99.9) and 98% (95% CI, 91.1-99.6). The 3- and 5-year CSS and OS were 97.7% (95% CI, 94.5-99.1), 95.3% (95% CI, 90.5-97.7), 94.4% (95% CI, 90.4-96.7), and 83.6% (95% CI, 76.1-88.9), respectively. Maximum detected acute skin toxicity was Grade (G) 0 in 71.8% of patients, G1 in 22.6%, G2 in 4.8%, G3 in 1%, and G4 in 0.3%. Treatment interruption occurred in 2 patients because of severe skin reactions. Late skin toxicity consisted of G1 fibrosis in 31.5% of patients, G2 in 4.2%, and G3 in 3.5%. Grade 1 edema was observed in 7% of patients, G2 in 4.2%, and G3 in 1.4%. G1 telangiectasia occurred in 1.8% and G3 in 0.7%. G1 hyperpigmentation was found in 4.6% of patients, G2 in 2.4%, and G1 atrophy was detected in 2.1%. Pain was observed as G1 in 13%, G2 in 1.8%, and G3 in 0.4%. Cosmetic results were good to excellent in 86.4% and fair to poor in 13.6%. ConclusionOnce-weekly hypofractionated WBRT (30-32-5 Gy in 5 fractions), delivered with standard tangential fields with the patient in the supine position seems feasible and effective for a selected population of primarily old breast cancer patients with predominantly low-risk features. This schedule might allow fragile patients to receive adjuvant WBRT after BCS, increasing radiotherapy accessibility and utilization.

Dosimetric Adequacy of the Non-delineated Post-operative Cavity in Whole Breast RadiotherapyTtreatment of Women with Early Breast Cancer

The delineation of the postoperative cavity (POC) is not common practice in tangential whole breast radiotherapy planning. Without a defined POC, the tumour bed may not be incorporated as part of the clinical target volume and risks the failure to deliver the intended therapeutic dose. The aim of this study is to review the location of the POC in relation to the radiotherapy dose distribution and the adequacy of coverage of POC using standard tangential whole breast treatment fields.

Abstract P5-14-19: Radiation field design on the ACOSOG Z0011 trial

Abstract Purpose/Objective: The landmark ACOSOG Z0011 trial established that axillary lymph node dissection (ALND) is unnecessary in breast cancer patients with one or two positive sentinel lymph nodes (SLN) who undergo lumpectomy, radiation therapy (RT) and systemic therapy. At a median follow-up of 6.3 years there were no differences in overall survival or local-regional recurrences between patients receiving ALND or SLN biopsy alone. The protocol required whole breast RT using standard tangential fields, but the extent of RT coverage of the regional nodes in these patients has not previously been described. We sought to ascertain this information. Methods: The RT data on the ACOSOG Z0011 trial was collected from case report forms completed by enrolling providers 18 months after enrollment. The response options on the forms included breast, supraclavicular, &amp; other. We reviewed these data and, in 2011-2013, we attempted to identify and contact all treating radiation oncology practices to request detailed radiation treatment records for central review. RT data was sent to the Quality Assurance Review Center (QARC) and reviewed by two independent radiation oncologists, blinded regarding the arm to which the patients were randomized. Results: Of the 891 patients enrolled on Z0011, 35 withdrew consent prior to surgery, leaving 856 who were analyzed in the primary report on trial outcomes.1 Among the 605 of these patients with a completed adjuvant radiation therapy form, 89% were noted to receive whole breast RT. Of these, 89 patients (15%) were recorded as also receiving treatment to the supraclavicular region. Detailed RT records were received on 228 patients: 104/389 (26.7%) and 124/404 (30.7%) on the ALND and SLND arms, respectively. Of the 228 patients, 185 patients (81.1%) received tangent-only treatment. Among these 185 patients, there was sufficient data to evaluate tangent field height in 142 (76.8%). High tangent RT fields (with cranial tangent border within 2 cm of the humeral head) were used in 52.6% (40/76) patients randomized to the ALND arm and 50% (33/66) patients randomized to the SLND arm. Of the 228 patients with records reviewed, 43 (18.9%) received directed regional nodal RT using ≥3 fields: 22 in the ALND and 21 in the SLND arm. Those receiving directed nodal RT tended to have greater nodal involvement (p&amp;lt;0.001). Conclusions: Most patients treated on the Z0011 trial received tangential field RT alone, and some received no radiotherapy at all. Some patients received directed nodal irradiation via a third field. In a subgroup for whom detailed RT records were available, the highest rates of directed nodal irradiation were among those with multiple nodes involved. As survival rates and local-regional recurrences were similar in the study arms, no conclusions can be drawn from this analysis on whether this additional radiation treatment was necessary or beneficial. 1JAMA 2011; 305 (6): 569-575. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-14-19.

Is There a Tradeoff in Using Modified High Tangent Field Radiation for Treating an Undissected Node-Positive Axilla?

IntroductionRecent data are changing axillary management in patients with 1 to 2 positive sentinel nodes. The proposed omission of completion axillary node dissection calls into question the need for axillary nodal irradiation. This study evaluates the difference in dose to the lung and heart and risk of radiation pneumonitis (RP) for patients treated with standard tangent fields (STF) compared with modified high tangent fields (MHTF). Materials and MethodsPlans of 30 patients treated with STF were evaluated. A second plan (MHTF) was developed to include axillary levels I (Ax1) and II (Ax2). Ax1 and Ax2 volumes were contoured based on the RTOG (Radiation Therapy Oncology Group) Atlas guidelines. Dose-volume histograms of the 2 plans were used to compare doses received by Ax1, Ax2, lung, and heart volumes. The risk of RP was calculated using normal tissue complication probability (NTCP) modeling. ResultsThe D95 (dose to 95% of volume) received by Ax1 and Ax2 volumes increased from 16.38 Gy and 5.71 Gy for STF to 49.38 Gy and 48.08 Gy for MHTF, respectively. Mean lung dose increased from 5.40 Gy for STF to 9.47 Gy for MHTF. Mean ipsilateral lung V5, V10, and V20 values increased from 19%, 14%, and 10%, respectively, for STF, to 32%, 24%, and 18%, respectively, for MHTF. Mean heart dose increased from 1.98 Gy for STF to 3.93 Gy for MHTF. Mean heart V25 and V30 values increased from 2% and 1%, respectively, for STF, to 4% and 3%, respectively, for MHTF. NTCP for RP increased from near 0% for STF to 1% for MHTF. ConclusionModified high tangent fields are necessary for definitive coverage of Ax1 and Ax2. This technique increases mean ipsilateral lung and heart doses as well as the V5, V10, and V20 of ipsilateral lung and the V25 and V30 of the heart. Risk of RP remains low by use of MHTF.

The standard tangential fields used for breast irradiation do not allow optimal coverage and dose distribution in axillary levels I–II and the sentinel node area

BackgroundRecent data from ACOSOG Z0011 and NSABP B32 trials suggested no need for axillary lymph node dissection (ALND) in patients with micrometastatic involvement of the sentinel lymph node (SLN). The low rate of axillary recurrence was attributed to the axilla coverage by the tangential fields (TgFs) irradiation and systemic therapy. This study aimed to evaluate dose distribution and coverage of the axilla levels I–II and the SLN area. Patients and methodsOne hundred and nine patients were analyzed according to three groups: group 1 (50 Gy; n = 18), group 2 (60 Gy; n = 34) and group 3 (66 Gy; n = 57). Patients were treated using the standard (STgF; n = 22) or high (HTgF; n = 87) TgF. ResultsThe median doses delivered to level I using HTgF versus STgF were 33 and 20 Gy (P = 0.0001). The mean dose delivered to the SLN area was only 28 Gy. Additionally, the SLN area was totally included in the HTgF in 1 out of 12 patients who had intraoperative clip placement in the SNL area. ConclusionsTgFs provide a limited coverage of the axilla and the SNLB area. This information should be considered when only TgFs are planned to target the axilla in patients with a positive SLN without ALND. Standardization of locoregional radiotherapy in this situation is urgently needed.

Is There a Tradeoff in Using Modified High Tangent Field Radiation for Treating an Undissected Node Positive Axilla?

Results of ACOSOG Z0011 are changing axillary management in patients with 1-2 positive lymph nodes. The proposed omission of complete axillary node dissection brings into question the need for axillary nodal irradiation. This study evaluates the difference in dose to the ipsilateral lung and heart and calculated risk of radiation pneumonitis (RP) for patients treated with standard tangential fields (STF) compared to modified high tangent fields (MHTF).

Modern Hypofractionation Schedules for Tangential Whole Breast Irradiation Decrease the Fraction Size-corrected Dose to the Heart

AimsHypofractionation of postoperative radiotherapy for breast cancer has been evaluated in a number of large randomised clinical trials, but concerns remain over the late cardiac toxicity. In this study, we examined the predictions of the linear quadratic model on the estimated fraction size-corrected dose to the heart for four evidence-based hypofractionation regimens. Materials and methodsDose plans for 60 left-sided breast cancer patients were analysed. All patients were planned with tangential fields for whole breast irradiation. Dose distributions were corrected to the equivalent dose in 2 Gy fractions (EQD2) using the linear quadratic model for five different fractionation schedules (50 Gy/25 fractions and four hypofractionation regimens) and for a range of α/β values (0–5 Gy). The mean EQD2 to the heart (DmeanEQD2) and the volume receiving 40 Gy (V40GyEQD2), both as calculated from the EQD2 dose distributions, were compared between schedules. ResultsFor α/β = 3 Gy, V40GyEQD2 favours hypofractionation for 40 Gy/15 fractions, 39 Gy/13 fractions and 42.5 Gy/16 fractions, but not for 41.6 Gy/13 fractions. All of the hypofractionation schedules result in lower DmeanEQD2 compared with normofractionation. These results hold as long as α/β ≳ 1.5 Gy. If the heart is blocked from the treatment beam, the fraction size-corrected dose is lower for the first three hypofractionation schedules, compared with normofractionation, even for α/β = ∼1 Gy. ConclusionFor standard tangential field whole breast irradiation, most of the examined hypofractionation schedules are estimated to spare the heart when compared with normofractionation. The dose to the heart, adjusted for fraction size using the linear quadratic model, will generally be lower after hypofractionated compared with normofractionated schedules, even for very low values of α/β.

Positive Sentinel Nodes Without Axillary Dissection: Implications for the Radiation Oncologist

Positive Sentinel Nodes Without Axillary Dissection: Implications for the Radiation Oncologist