The modified tangential irradiation technique for breast cancer: how to cover the entire axillary region

Mapping of Level I Axillary Lymph Nodes in Patients with Newly Diagnosed Breast Cancer: Optimal Target Delineation and Treatment Techniques for Breast and Level I Axilla irradiation

PURPOSE

To map the locations of level I axilla (Ax-L1) lymph nodes (LNs), evaluate the clinical target volume (CTV) coverage defined by the Radiation Therapy Oncology Group (RTOG) breast cancer atlas, and assess the optimal techniques for whole-breast and Ax-L1 irradiation (WBI + Ax-L1).

MATERIALS AND METHODS

We identified 76 newly diagnosed breast cancer patients with 1-4 positive LNs confirmed by axillary dissection. The locations of 116 involved Ax-L1 LNs on diagnostic computed tomography (CT) were mapped onto simulated CT images of a standard patient. Ax-L1 LN coverage by the RTOG atlas was evaluated, and a modified Ax-L1 CTV with better coverage was proposed. Treatment plans were designed for WBI + Ax-L1 with high tangential simplified intensity-modulated radiation therapy (HT-sIMRT) and volumetric modulated arc therapy (VMAT), and for WBI + RTOG Ax-L1 with VMAT with a prescription dose of 50 Gy in 25 fractions, respectively. The differences in dosimetric parameters were compared.

RESULTS

The RTOG atlas missed 29.3% of LNs. Modification by extending 1 cm caudal and 0.5 cm anterior to the RTOG-defined CTV borders allowed the modified Ax-L1 CTV to encompass 90.5% of LNs. All plans met the required prescription dose to WBI and Ax-L1. The mean dose and V20 and V5 of the ipsilateral lung were 11.7Gy, 23.0%, 38.1% for HT-sIMRT WBI + Ax-L1, and 8.9 Gy, 16.4%, 32.5% for VMAT WBI + Ax-L1 plans, respectively. The mean heart doses in the left-sided plans were 3.2Gy and 3.0Gy, respectively. The V30 of the humeral head and minimum dose to the axillary-lateral thoracic vessel junction were 2.0% vs 1.8%, and 45.5Gy vs 45.7Gy for VMAT WBI + Ax-L1 and VMAT WBI + RTOG Ax-L1 plans, respectively.

CONCLUSIONS

A modified Ax-L1 CTV with expansion of the caudal and anterior borders might provide better coverage. Compared with HT-sIMRT WBI + Ax-L1, VMAT WBI+ Ax-L1 provided an adequate dose to Ax-L1 with decreasing the doses to most normal tissues. Coverage of modified Ax-L1 did not increase the dose to organs-at-risk compared with coverage of RTOG Ax-L1.

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

Purpose

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.

Material and methods

Individual topography of ASLN was determined in 151 women with clinical T1-2N0M0 breast cancer. SPECT-CT visualization of ASLNs was initiated 120 min 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.

Results

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".

Conclusion

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.

Coverage of Axillary Lymph Nodes with Tangential Breast Irradiation in Korea: A Multi-Institutional Comparison Study

Introduction. To evaluate the dose distribution and coverage of axilla using only tangential field for whole breast radiotherapy (RT) at three institutions in Korea. Methods. We used computed tomography (CT) images of nine consecutive 1-2 sentinel lymph node-positive patients who underwent breast conserving surgery and whole breast RT without axillary lymph node (ALN) dissection for clinical T1-2N0 breast cancer. The CT data were transferred to three radiation oncologists in 3 institutions and each radiation oncologist created treatment plans for all nine patients; a total of 27 treatment plans were analyzed. Results. The mean doses delivered to levels I and II were 31.9 Gy (9.9–47.9 Gy) and 22.3 Gy (3.4–47.7 Gy). Ninety-five percent of levels I and II received a mean dose of 11.8 Gy (0.4–43.0 Gy) and 3.0 Gy (0.3–40.0 Gy). The percent volumes of levels I and II covered by 95% of the prescribed dose were only 29.0% (0.2–74.1%) and 11.5% (0.0–70.1%). The dose distribution and coverage of axilla were significantly different between three institutions (p = 0.001). Conclusion. There were discrepancies in ALN coverage between three institutions. A standardization of whole breast RT technique through further research with a nationwide scale is needed.

Virtual lymph node analysis to evaluate axillary lymph node coverage provided by tangential breast irradiation

PURPOSE

To investigate the coverage of axillary lymph node with tangential breast irradiation fields by using virtual lymph node (LN) analysis.

MATERIALS AND METHODS

Forty-eight women who were treated with whole breast irradiation after breast-conserving surgery were analyzed. The axillary and breast volumes were delineated according to the Radiation Therapy Oncology Group (RTOG) contouring atlas. To generate virtual LN contours, preoperative fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scans with identifiable LN were fused with the CT scans, and the virtual LN contour were delineated on the CT.

RESULTS

The median level I and II axillary volume coverage percentages at the VD95% line were 33.5% (range, 5.3% to 90.4%) and 0.6% (range, 0.0% to 14.6%), respectively. Thirty-one LNs in 18 patients were delineated (26 in level I and 5 in level II). In the level I axilla, 84.6% of virtual LNs were encompassed by the 95% isodose line. In the level II axilla, by contrast, none of the virtual LNs were encompassed by the 95% isodose volumes. There was a substantial discrepancy between the RTOG contouring atlas-based axillary volume analysis and the virtual LN analysis, especially for the level I axillary coverage. The axillary volume coverage was associated with the body mass index (BMI) and breast volume.

CONCLUSION

The tangential breast irradiation did not deliver adequate therapeutic doses to the axillary region, particularly those in the level II axilla. Patients with small breast volumes or lower BMI showed reduced axillary coverage from the tangential breast fields. For axillary LN irradiation, individualized anatomy-based radiation fields for patients would be necessary.

Omission of axillary lymph node dissection for clinically node negative early-stage breast cancer patients

BACKGROUND

For clinically node negative (N0) breast cancer patients, sentinel node (SN) biopsy (SNB) is a standard technique and complete axillary lymph node dissection (ALND) remains the standard treatment when the SN is positive. However, the American College of Surgeons Oncology Group Z0011 trial and the International Breast Cancer Study Group 23-01 trial showed that SNB without ALND can offer excellent regional control and equal survival compared with ALND for limited macrometastatic and micrometastatic SN involvement, respectively. We retrospectively evaluated axillary control rates in clinically N0 patients who had no axillary surgical treatment.

METHODS

Data on 158 patients who underwent breast-conserving therapy without any axillary surgical procedure between 1994 and 2010 were extracted. The last follow-up was on May 2013, and the overall median follow-up period was 119.0 months.

RESULTS

Of all 158 patients, 10 (6.3 %) and 3 (1.9 %) developed locoregional and axillary recurrences, respectively. The 10-year locoregional and axillary recurrence rates were 5.8 and 2.1 %, respectively. The 5- and 10-year overall survival rates were 94.0 and 84.8 %, respectively. Cases with axillary recurrence tended to have common risk factors for recurrence.

CONCLUSION

Even if SNB and ALND were omitted, local and regional recurrence rates were very low among clinically N0 patients and were at the same levels shown in recent trials. This suggests that at least ALND might be safely avoided in clinically N0 patients without any obvious risk factors regardless of axillary nodal status after SNB.

Axillary Irradiation with High Tangent Fields for Clinically Node-Negative Breast Cancer: Can 3-D Conformal Radiotherapy with a Field-in-Field Technique Better Control the Axilla?

BACKGROUND

The target volume for postoperative breast irradiation is the remaining breast tissue, and the axillary region is not an intentional target volume.

PATIENTS AND METHODS

Between 2001 and 2009, eligible women with pT1-2cN0/pN0(sn) breast cancer underwent breast-conserving therapy without axillary dissection. Treatment outcomes between 2 radiotherapy planning groups, high tangent fields with 2-dimensional (2-D) simulation-based planning and 3-dimensional (3-D) computed tomography-based planning with a field-in-field technique, were compared. The correlating factors for axillary failure were also calculated.

RESULTS

In total, 678 patients were eligible. As of May 2009, the median follow-up times for the 2-D (n = 346) and 3-D (n = 332) groups were 94 and 52 months, respectively. Patient characteristics were balanced, except for a younger population in the 2-D group and more lymphovascular invasion in the 3-D group. On multivariate analysis, 2-D planning was the only risk factor for axillary failure. In the 2-D and 3-D groups, the 5-year cumulative incidences of axillary failure were 8 (3.1%) and 1 (0.3%) (log-rank p = 0.009), respectively. The respective 5-year overall survival rates were 97.4 and 98.4% (p = 0.4).

CONCLUSION

High tangent irradiation with 3-D planning improved axillary control compared to that with 2-D planning, suggesting that optimizing axillary dose distribution may impact outcomes.

Complication rates in patients with negative axillary nodes 10 years after local breast radiotherapy after either sentinel lymph node dissection or axillary clearance

BACKGROUND

We assess complication rates in node negative breast cancer patients treated with breast radiotherapy (RT) only after sentinel lymph node dissection (SLND) or axillary lymph node dissection (ALND).

MATERIALS AND METHODS

Between 1995 and 2001, 226 women with AJCC stage I-II breast cancer were treated with lumpectomy, either SLND or SLND+ALND, and had available toxicities in follow-up: 111/136 (82%) and 115/129 (89%) in SLND and ALND groups, respectively. RT targeted the breast to median dose of 48.2 Gy (range, 46.0 to 50.4 Gy) without axillary RT. Chi-square tests compared complication rates of 2 groups for axillary web syndrome (AWS), seroma, wound infection, decreased range of motion of the ipsilateral shoulder, paresthesia, and lymphedema.

RESULTS

Median follow-up was 9.9 years (range, 8.3-15.3 y). Median number of nodes assessed was 2 (range, 1-5) in SLND and 18 (range, 7-36) in ALND (P < 0.0001). Acute complications occurred during the first 2 years and were AWS, seroma, and wound infection. Incidences of seroma 5/111 (4.5%) in SLND and 16/115 (13.9%) in ALND (P < 0.02, respectively) and wound infection 3/111 (2.7%) in SLND and 10/115 (8.7%) in ALND (P < 0.05, respectively) differed significantly. AWS was not statistically different between the groups. At 10 years, the only chronic complications decreased were range of motion of the shoulder 46/111 (41.4%) in SLND and 92/115 (80.0%) in ALND (P < 0.0001), paresthesia 12/111 (10.8%) in SLND and 39/115 (33.9%) in ALND (P < 0.0001), and lymphedema assessed by patients 10/111 (10.0%) in SLND and 39/115 (33.9%) in ALND (P < 0.0001). Chronic lymphedema, assessed by clinicians, occurred in 6/111 (5.4%) in SLND and 21/115 (18.3%) in ALND cohorts, respectively (P < 0.0001).

CONCLUSIONS

Our mature findings support that in patients with negative axillary nodal status SLND and breast RT provide excellent long-term cure rates while avoiding morbidities associated with ALND or addition of axillary RT field.

Outcomes of clinically node-negative breast cancer without axillary dissection: can preserved axilla be safely treated with radiation after a positive sentinel node biopsy?

PURPOSE

We analyzed whether axillary nodal irradiation could control clinically node-negative disease, including those patients with a positive sentinel lymph node biopsy (SLNB), most of whom received regional nodal irradiation. We also evaluated toxicity profiles that resulted from nodal irradiation.

PATIENTS AND METHODS

From 1988 to 2011, 2107 patients with cT1-T2N0M0 breast cancer underwent breast conservation therapy in the absence of axillary dissection: nx group (n = 1548), without any axillary surgery; the sn(-) group (n = 518), with a negative SLNB; and sn(+) group (n = 104), with a positive SLNB.

RESULTS

The median follow-up times were 88, 56, and 55 months for the nx, sn(-), and sn(+) groups, respectively. The nx group had more risk factors than did the other 2 groups in terms of age, grade, or T stage. Ninety-eight percent of the sn(-)group received only tangent irradiation, and 100% and 83% of the sn(+) and nx group, respectively, received additional regional nodal irradiation. The 5-year cumulative incidences of axillary failure and regional nodal failure were 34, 3, and 0 (2.7%, 0.7%, and 0%; P = .02, log-rank test) and 57, 4, and 0 (4.4, 1%, and 0; P = .04), respectively. Overall survival rates in 5 years were 96.4%, 98.9%, and 97.6% (P = .03), respectively. Symptomatic but transient radiation pneumonitis developed in 31, 16, and 6 (2.0%, 3.1%, and 5.7%). Mild arm edema was observed in 1, 4, and 0 (0.06%, 0.8%, and 0%) in the nx, sn(-), sn(+) groups, respectively.

CONCLUSIONS

Treatment without axillary dissection showed excellent outcomes with negligible toxicity for patients with clinically node negative, including those with a positive SLNB. Regional nodal irradiation after a positive SLNB is a reasonable alternative to axillary dissection.

How do I deal with the axilla in patients with a positive sentinel lymph node?

OPINION STATEMENT

Optimal management of the axilla in a patient with a positive sentinel node biopsy is not yet defined.These patients usually have Breast Conserving Surgery and receive adjuvant systemic therapy and whole breast radiation.Treatment options for the axilla include: no further surgery with or without radiation completion axillary nodal dissection with or without radiation Radiation options in addition to whole breast radiation include axillary and supraclavicular nodal irradiation regional nodal irradiationincludes supraclavicular and internal mammary nodes Completion axillary dissection has been standard practice in patients with positive sentinel nodes. the number of involved nodes provides prognostic information. theoretically improves local control, but may be obviated by systemic chemotherapy. but avoidance of dissection may not adversely affect locoregional control or survival. dissection has significant morbidity so safe avoidance is desirable. There is little worldwide concordance on the use of radiation: whole breast radiation (commonly used after breast conserving surgery) may radiate the lower axilla supraclavicular radiation is most commonly recommended for patients with four or more nodes but may confer a survival benefit on patients with lower risk disease. adding nodal irradiation reduces local recurrence with only modest toxicity. Adjuvant systemic therapy provides a survival benefit for patients with nodal disease. Most will receive cytostatic chemotherapy containing an anthracycline and a taxane. Hormone therapy is appropriate for estrogen receptor positive disease. The extent to which systemic therapy controls microscopic nodal disease is unknown. Node positive patients should generally receive adjuvant chemotherapy.A small group of patients benefit from specific nodal therapy. Further studies are needed to better identify these patients.

Coverage of axillary lymph nodes with high tangential fields in breast radiotherapy

The aim of this study is to evaluate the coverage of axillary nodal volumes with high tangent fields (HTF) in breast radiotherapy and to determine the utility of customised blocking. The treatment plans of 30 consecutive patients with early breast cancer were evaluated. The prescription dose was 50 Gy to the whole breast. Axillary level I-II lymph node volumes were delineated and the cranial border of the tangential fields was set just below the humeral head to create HTF. Dose-volume histograms (DVH) were used to calculate the doses received by axillary nodal volumes. In a second planning set, HTF were modified with multileaf collimators (MLC-HTF) to obtain an adequate dose coverage of axillary nodes. The mean doses of the axillary nodes, the ipsilateral lung and heart were compared between the two plans (HTF vs MLC-HTF) using a paired sample t-test. The doses received by 95% of the breast volumes were not significantly different for the two plans. The doses received by 95% of the level I and II axillary volumes were 16.79 Gy and 11.59 Gy, respectively, for HTF, increasing to 47.2 Gy and 45.03 Gy, respectively, for MLC-HTF. Mean lung doses and per cent volume of the ipsilateral lung receiving 20 Gy (V20) were also increased from 6.47 Gy and 10.47%, respectively, for HTF, to 9.56 Gy and 16.77%, respectively, for MLC-HTF. Our results suggest that HTF do not adequately cover the level I and II axillary lymph node regions. Modification of HTF with MLC is necessary to obtain an adequate coverage of axillary levels without compromising healthy tissue in the majority of the patients.

A 10-year follow-up of treatment outcomes in patients with early stage breast cancer and clinically negative axillary nodes treated with tangential breast irradiation following sentinel lymph node dissection or axillary clearance

We compare long-term outcomes in patients with node negative early stage breast cancer treated with breast radiotherapy (RT) without the axillary RT field after sentinel lymph node dissection (SLND) or axillary lymph node dissection (ALND). We hypothesize that though tangential RT was delivered to the breast tissue, it at least partially sterilized occult axillary nodal metastases thus providing low nodal failure rates. Between 1995 and 2001, 265 patients with AJCC stages I-II breast cancer were treated with lumpectomy and either SLND (cohort SLND) or SLND and ALND (cohort ALND). Median follow-up was 9.9 years (range 8.3-15.3 years). RT was administered to the whole breast to the median dose of 48.2 Gy (range 46.0-50.4 Gy) plus boost without axillary RT. Chi-square tests were employed in comparing outcomes of two groups for axillary and supraclavicular failure rates, ipsilateral in-breast tumor recurrence (IBTR), distant metastases (DM), and chronic complications. Progression-free survival (PFS) was compared using log-rank test. There were 136/265 (51%) and 129/265 (49%) patients in the SLND and ALND cohorts, respectively. The median number of axillary lymph nodes assessed was 2 (range 1-5) in cohort SLND and 18 (range 7-36) in cohort ALND (P < 0.0001). Incidence of AFR and SFR in both cohorts was 0%. The rates of IBTR and DM in both cohorts were not significantly different. Median PFS in the SLND cohort is 14.6 years and 10-year PFS is 88.2%. Median PFS in the ALND group is 15.0 years and 10-year PFS is 85.7%. At a 10-year follow-up chronic lymphedema occurred in 5/108 (4.6%) and 40/115 (34.8%) in cohorts SLND and ALND, respectively (P = 0.0001). This study provides mature evidence that patients with negative nodes, treated with tangential breast RT and SLND alone, experience low AFR or SFR. Our findings, while awaiting mature long-term data from NSABP B-32, support that in patients with negative axillary nodal status such treatment provides excellent long-term cure rates while avoiding morbidities associated with ALND or addition of axillary RT field.

A calibration phantom for direct, in vivo measurement of 241Am in the axillary lymph nodes

A calibration phantom was developed at the University of Cincinnati (UC) to determine detection efficiency and estimate the quantity of activity deposited in the axillary lymph nodes of a worker who had unknowingly sustained a wound contaminated with 241Am at some distant time in the past. This paper describes how the Livermore Torso Phantom was modified for calibrating direct, in vivo measurements of 241Am deposited in the axillary lymph nodes. Modifications involved milling a pair of parallel, flat bottom, cylindrical holes into the left and right shoulders (below the humeral head) of the Livermore Torso Phantom in which solid, 1.40-cm-diameter cylindrical rods were inserted. Each rod was fabricated using a muscle tissue substitute. One end of each rod contained a precisely known quantity of Am sealed in a 1-cm-diameter, 2.54-cm-deep well to simulate the axillary lymph nodes when inserted into the modified Livermore Torso Phantom. The fixed locations for the axillary lymph nodes in the phantom were determined according to the position of the Level I and the combined Level II + III axillary lymph nodes reported in the literature. Discrete calibration measurements for 241Am in the simulated axillary lymph nodes located in the right and left sides of the thorax were performed using pairs of high-resolution germanium detectors at UC and Lawrence Livermore National Laboratory. The percent efficiency for measuring the 59.5 keV photon from Am deposited in the right and left axillary lymph nodes using a pair of 3,000 mm2 detectors is 2.60 +/- 0.03 counts gamma-1 and 5.45 +/- 0.07 counts gamma-1, respectively. Activity deposited in the right and left axillary lymph nodes was found to contribute 12.5% and 19.7%, respectively, to a lung measurement and 1.2% and 0.2%, respectively, to a liver measurement. Thus, radioactive material mobilized from a wound in a finger or hand and deposited in the axillary lymph nodes has been shown to confound results of a direct, in vivo measurement of the lungs.

Dose received by the sentinel node volume during tangential radiation therapy to the breast

The dose received by the sentinel node (SN) volume during tangential irradiation was studied on 31 patients. Of the 50Gy prescribed to the breast volume 95% of the SN volume received from 6.9 to 27.5Gy. In 19 patients the SN volume overlapped with the tangential field deep side.

Is the Berg Axillary Lymph Node Categorization Useful in the 3D Environment?

OBJECTIVE

The Berg muscle-based categorization of axillary lymph node location (commonly referred to as levels I, II, and III) was used extensively by pathologists and surgeons to describe the extent of axillary node dissection in breast cancer patients. However, its reproducibility with different arm positions and utility in 3-dimensional radiation treatment planning hasn't been tested.

METHODS

Computed tomography scans were observed in 16 patients in 2 positions: historical position (HP), ipsilateral arm abducted 90 degrees to the body axis; standard position (SP), arms above head. The volume, contents, and location of Berg lymph node levels (LNL) and the location of lymph nodes, surgical clips, pectoral muscles, and vascular structures relative to reference points were compared.

RESULTS

From HP to SP there was no difference in LNL volumes. However, if measured from an anatomic landmark, the third thoracic vertebra (T3), LNL position varied: level I, an average of 23.1 mm anteriorly, P < 0.01; level II, 7.5 mm medially, P = 0.04; level III, 18.8 mm medially, P = 0.05. Using T3 as a reference: pectoralis major and minor muscles displaced medially (23.9 mm, P < 0.01 and 7.5 mm, P = 0.09) and anteriorly (18.2 mm, P < 0.01 and 11.2 mm, P < 0.01); axillary (18.0 mm, P < 0.01), subscapular (25.4 mm, P < 0.01), and lateral thoracic (8.4 mm, P < 0.01) vessels displaced anteriorly; axillary vessels displaced also medially (15.1 mm, P = 0.03). Disagreements in LN coverage with changes in arm position were observed in 60% (LNs) and 66% (clips) for level II.

CONCLUSIONS

Surgeons, radiologists, and radiation oncologists should be aware that LNL coverage based on muscle boundaries varies significantly with arm position changes, making objective comparisons of information collected in different arm positions unreliable.

Radiation therapy after breast-conserving surgery

The authors critically reviewed previous articles concerning the significance of breast irradiation following breast-conserving surgery in terms of the following subject items: indications for breast-conserving therapy, the significance and complications of breast irradiation, the timing of the start of breast irradiation, the significance of boost irradiation, the potential improvement of survival with systemic therapy plus breast irradiation, the significance of axillary dissection, indications and the significance of regional nodal irradiation, accelerated hypofractionated radiotherapy, omission of breast irradiation in low-risk patients, and future directions. In addition, our previously reported results of breast irradiation following breast-conserving surgery at the Keio University Hospital are outlined. Our newly developed tangential irradiation technique directed to the axilla and a recently introduced three-dimensional simulation technique for radiotherapy treatment planning are also presented.

CT localization of axillary lymph nodes in relation to the humeral head: Significance of arm position for radiation therapy planning

Irradiation of the axillary nodes is often indicated in the clinical radiotherapy of patients with lymphoma and breast cancer. The relative location of the axillary nodes and the humeral head has historically been estimated based on lymphangiographic data. Since CT offers more precise definition, the axillary nodal region in relation to the humeral head was systematically studied in 61 patients undergoing CT simulation for breast conservation therapy. Differences in arm position (degree of abduction) significantly affected the location of the axillary nodal region in relation to the humeral head. With the arm abducted beyond 55 degrees, humeral head blocking would result in blocking of some of the axillary nodes.

Irradiation with standard tangential breast fields in patients treated with conservative surgery and sentinel node biopsy: using a three-dimensional tool to evaluate the first level coverage of the axillary nodes

Recent data show that axillary coverage can be obtained, but only through a selective CT-based treatment planning, as standard tangential fields are inadequate to deliver therapeutic doses. Currently, the replacement of axillary dissection with new techniques, such as sentinel node (SN) biopsy, makes it necessary to re-address the question about the real role of axillary irradiation, complicated by the differences in the anatomy of dissected and undissected axillary regions. The purpose of this paper is the dosimetric analysis of first axillary level coverage in standard irradiation of 15 breast-cancer patients treated with quadrantectomy and SN biopsy (negative finding). During surgery a clip on the site of the SN was positioned, marking the caudal margin of first axillary level. After the breast treatment plan was completed, the first axillary level was contoured on CT scans, from the site of the surgical clip up to the sternal manubrium, for coverage analysis with dose-volume histograms (DVHs) and three-dimensional isodose visualization. The maximum dose mean ranged from 5% to 80% of the prescribed dose (mean value 48.7%). The mean total dose received by the volume of interest was lower than 40 Gy in all but one patient. No patient had total irradiation of first nodal level; only one patient had 35% of the volume enclosed in the 100% isodose. Our analysis lead to the conclusion that therapeutic doses are not really delivered to first level axillary level nodes by a standard tangential field technique, and that specific treatment planning and beam arrangement are required when adequate coverage is necessary.

Analysis of axillary coverage during tangential radiation therapy to the breast

PURPOSE

To evaluate the percent of the prescribed radiation dose to the breast delivered to the axillary tissue and to evaluate the volume of the axilla receiving 95% of the prescribed dose with normal and with high tangential fields.

METHODS AND MATERIALS

Computed tomographic scan images with 5-mm sections were retrospectively analyzed for 35 patients who had undergone three-dimensional (3D) planning for whole-breast radiation. The axillary nodal region was identified and divided into Levels I to III and Rotter's nodes (RN). Digitally reconstructed radiographs were created, and two plans were developed: (a) the standard clinical opposed tangential irradiation fields and (b) the high-tangential irradiation fields. Axillary coverage was examined by use of dose-volume histograms (DVH), and the average coverage for the four nodal groups was obtained.

RESULTS

The data show that with the standard tangential irradiation fields, the average dose delivered to Levels I, II, III, and RN is 66% (standard deviation, or SD = 13%), 44% (SD = 18%), 31% (SD = 20%), and 70% (SD = 19%) of the prescribed dose, respectively. The coverage increases to 86% (SD = 9%), 71% (SD = 19%), 73% (SD = 17%), and 94% (SD = 8%) of the prescribed dose, respectively, for Levels I, II, III, and RN when the high tangential irradiation fields are used. 51% of Level I, 26% of Level II, and 15% of Level III receive 95% of the prescribed dose with normal tangents. The volume increases to 79%, 51%, and 49% of Levels I, II, and III, respectively, with high tangents.

CONCLUSION

The tangential fields designed to treat only the breast do not adequately cover the axillary region and, therefore, cannot be relied upon for prophylactic therapy of the axilla. The high tangential irradiation fields increase the dosages received by the axillary region, but the average dosages received by the lower axillary regions are still less than 90% of the prescribed dose.

Treatment of breast carcinoma in patients with clinically negative axillary lymph nodes using radiotherapy versus axillary dissection

BACKGROUND

The role of axillary lymph node dissection (AxD) for patients with breast carcinoma who have clinically negative lymph nodes (cN0) and undergo breast-conserving therapy has been controversial. If patients do not undergo AxD, then it is uncertain whether specific lymph node irradiation should be given. The authors compared the results obtained from patients w ho underwent AxD with the results from patients who received axillary irradiation (AxR) using one of two radiotherapy techniques.

METHODS

Patients with T1-T2cN0 breast carcinoma were treated from 1983 to 2002 with either AxD (80 patients) or AxR (1134 patients received tangential-field [2-field] irradiation, and 303 patients received 3-field irradiation). The median follow-up was 161 months for the AxD group and 66 months for the AxR group (55 months for patients who received tangential-field irradiation, and 122 months for patients who received 3-field irradiation).

RESULTS

One patient in the AxD group and 35 patients in the AxR group had axillary recurrences. The 10-year cumulative axillary recurrence rates were 1.3% and 4.6% for the AxD group and the AxR group, respectively (P = 0.21). For patients with T1 tumors, the 10-year overall survival rates for the two groups were 94.7% and 92.7%, respectively (P = 0.34); and, for patients with T2 tumors, the 10-year overall survival rates were 92.5% and 89.1%, respectively (P = 0.34). In the AxR group, the 5-year axillary recurrence rates were 2.5% for patients who received tangential-field irradiation and 1.7% for patients who received 3-field irradiation (P = 0.18), and the 5-year regional recurrence rates for the two groups were 4.8% and 2.4%, respectively (P = 0.048). On multivariate analysis, positive lymphovascular invasion, outer tumor location, and larger tumor size were significant risk factors for regional failure.

CONCLUSIONS

For patients with cN0 breast carcinoma, AxD and AxR yielded the same overall survival rates. Most patients can be treated safely with tangential-field irradiation alone. Patients who are at increased risk of regional failure may benefit from three-field irradiation.

Loco-regional conformal radiotherapy of the breast: delineation of the regional lymph node clinical target volumes in treatment position

BACKGROUND AND PURPOSE

As the location of the regional lymph nodes (LNs) of the breast varies largely between patients and may be dependant on the position of the arm, adequate localization of these nodes is mandatory in order to fully take advantage of optimized conformal radiotherapy. For this purpose, the anatomical boundaries of the regional lymph node (LN) clinical target volumes (CTVs) for delineation on transverse CT-slices, made in treatment position, were established.

PATIENTS AND METHODS

Anatomical and surgical descriptions of the regional LNs of the breast, as well as a shoulder dissection, were studied. Axial slices of a human cadaver with one arm in abduction and the other in adduction were investigated, to assess the displacement of LNs by abduction of the arm into treatment position. Based on these findings, we defined the anatomical boundaries of the regional LN CTVs visible on transverse CT-slices.

RESULTS

Standard anatomical and surgical descriptions appeared to be inadequate for determination of the boundaries of the regional LN CTVs in treatment position. With abduction of the arm, a change in position of all regional LNs, except for the medial supraclavicular LNs and internal mammary LNs, was observed in the anatomical cross-sections. This was also taken into account in our delineation protocol proposal.

CONCLUSIONS

Anatomically based guidelines for delineation of the regional LN CTVs for loco-regional irradiation of the breast on transverse CT-slices, made in treatment position, have been developed in this study. These could be used as a basis for conformal radiotherapy.

Evaluation of novel modified tangential irradiation technique for breast cancer patients using dose–volume histograms

PURPOSE

We have previously reported that entire axillary lymph node regions could be irradiated by the modified tangential irradiation technique (MTIT). In this study, MTIT was compared with a conventional irradiation technique (CTIT) using dose-volume histograms to verify how adequately MTIT covers the breast and axillary lymph node region and the extent to which it involves the lung and heart.

METHODS AND MATERIALS

Forty-four patients with early-stage breast cancer were treated by lumpectomy, axillary dissection, and postoperative radiotherapy. Twenty-two patients were treated with MTIT and 22 with CTIT. In 25 patients, the breast tumor was on the left and in 19 on the right. During axillary dissection, surgical clips were left as markers at the border of the axillary lymph node region. MTIT was planned by setting the dorsal edge of the radiation field on a lateral-view simulator film at the dorsal edge of the humeral head and the cranial edge of the radiation field at the caudal edge of the humeral head. CTIT was planned to ensure radiation of the breast tissue without considering the axillary region. In this study, all patients underwent computed tomography, and the CT data were transmitted on-line to a radiotherapy planning system, in which the dose-distribution computed tomography images and dose-volume histograms were calculated by defining the breast, axillary region (levels I, II, and III), lung, and heart region.

RESULTS

Dose-volume histogram analysis demonstrated that breast tissue was radiated with an 86.5-100% volume (median 96.5%) by MTIT and an 83-100% volume (median, 95%) by CTIT at >95% of the isocenter dose. The axillary lymph node regions at Levels I, II, and III were irradiated with 84-100% (median, 94.5%), 59-100% (median, 89%), and 70-100% (median, 89.5%) volumes, respectively, by MTIT and with 2-84% (median, 38%), 0-53% (median, 15%), and 0-31% (median, 0%) volumes, respectively, by CTIT at >70% of the isocenter dose. The ipsilateral lung was irradiated with a 5-22% volume (median, 11.5%) by MTIT and 5-15% volume (median 9%) by CTIT at >90% of the isocenter dose. In all 25 left-sided breast cancer patients, the volumes irradiated with an 80% isocenter dose were <30 cm(3).

CONCLUSION

The results of our study demonstrated that the breast tissue was sufficiently irradiated with both CTIT and MTIT planning, the axillary lymph node areas irradiated by MTIT were much wider than those irradiated by CTIT at all levels, and the lung and heart volumes irradiated by MTIT were small.

Quality assurance of axillary radiotherapy in the EORTC AMAROS trial 10981/22023: the dummy run

PURPOSE

To assess and if needed improve the compliance of participating institutions to the radiotherapy guidelines of the EORTC AMAROS trial 10981/22023 comparing axillary radiotherapy to axillary surgery in sentinel node positive patients with early stage breast cancer.

MATERIALS AND METHODS

A transverse contour and a frontal view radiograph of the axillary region of a 'dummy' patient were sent to all institutions intending to participate in the trial with the request to produce a radiotherapy treatment plan according to the protocol guidelines. Additional information on dose prescription, the treatment technique and field matching with breast fields and internal mammary lymph node fields was requested in a questionnaire.

RESULTS

Eighteen institutions have performed the dummy run. At first assessment, the dose was not specified according to the protocol in seven cases, while two institutions did not comply with the dose prescription of 50 Gy in 25 fractions. Dose heterogeneity was over 20% in 10 institutions, caused by the use of a two-field technique in eight cases. Ten institutions did not apply special techniques to obtain non-overlapping match planes. In 10 cases, one or more field borders or blocks were positioned incorrectly. Following recommendations from the quality assurance committee given to the participating institutions on an individual basis, 10 institutions adapted their technique. Thereafter, 16 institutions could be accepted for trial participation.

CONCLUSIONS

A number of potential protocol deviations were found at first assessment. Since recommendations led to a large number of adaptations by the participants, a considerable improvement in protocol compliance and inter-institutional consistency was achieved.

Evaluation of level I and II axillary nodes included in the standard breast tangential fields and calculation of the administered dose: results of a prospective study

PURPOSE

To evaluate if Level I and II axillary nodes are included in the standard breast tangential fields, and to calculate the dose administered.

METHODS AND MATERIALS

In 35 patients treated with conservative surgery and axillary dissection, three clips were surgically positioned: one at the beginning of Level I, one between Level I and II, and another at the end of Level II. The breast was irradiated with two tangential fields. On simulation films, the volume between the clips was scored as "entirely included" or "not entirely included" in the treatment fields. Computed tomography (CT) scans were performed; CT data were imported into a treatment planning system, and three-dimensional plans were devised. Axillary Levels I and II were delineated on CT slices on the basis of anatomic landmarks. Fields and isodose curves previously obtained were superimposed to calculate the dose administered to the first two axillary node levels and to 90% of both volumes.

RESULTS

On X-rays, the volume between clips corresponding to Level I was completely included in the medial field in 66.7% of cases and in the lateral field in 63.7% of cases, whereas the volume of Level II was entirely included in the medial field in 54.5% of cases and in the lateral field in 45.4% of cases. The median dose administered to Level I and II was 38.58 Gy +/- 11.01 (range 3.46-47.14) and 20.65 Gy +/- 14.07 (range 0.95-38.94), respectively. The median dose to 90% of both volumes of Level I and II was 6.75 Gy +/- 14.01 (range 1.9-39) and 1.75 Gy +/- 9.72 (range 0.8-29), respectively.

CONCLUSION

The standard tangential fields do not entirely include Levels I and II axillary nodes.