Elective breast radiotherapy including level I and II lymph nodes: A planning study with the humeral head as planning risk volume
© The Author(s). 2017
Received: 14 June 2016
Accepted: 28 December 2016
Published: 18 January 2017
The aim of this study was to assess the dose to the humeral head planning risk volume with the currently used high tangential fields (HTF) and compare different planning techniques for breast radiotherapy including axillary level I and II lymph nodes (PTVn) while sparing the humeral head.
Ten patients with left-sided breast cancer were enrolled in a planning study with 16 fractions of 2.66 Gy. Four planning techniques were compared: HTF, HTF with sparing of the humeral head, 6-field IMRT with sparing of the humeral head and VMAT with sparing of the humeral head. The humeral head + 10 mm was spared by restricting V40Gy < 1 cc.
The dose to the humeral head was too high with HTF (V40Gy on average 20.7 cc). When sparing the humeral head in HTF, PTVn V90% decreased significantly from 97.9% to 89.4%. 6-field IMRT and VMAT had a PTVn V90% of 98.2% and 99.5% respectively. However, dose to the lungs, heart and especially the contralateral breast increased with VMAT.
The humeral head is rarely spared when using HTF. When sparing the humeral head, the 6-field IMRT technique leads to adequate PTV coverage while not increasing the dose to the OARs.
KeywordsBreast radiotherapy Lymph nodes IMRT VMAT Humeral head Planning study
In case of limited metastatic sentinel node involvement the choice between axillary dissection or breast irradiation with or without axillary radiotherapy does not seem to make much difference in terms of regional relapse and survival. Both treatment modalities lead to sporadic regional recurrences [1, 2]. Irradiated volume and toxicity are related and this relationship plays a role in the choice of treatment.
Several studies reported decreased mobility of the shoulder after radiotherapy [1, 3–6]. The AMAROS trial compared radiotherapy and surgery of the axilla for patients with a positive sentinel lymph node . Both groups reported decreased arm mobility with a worse quality of life for patients that underwent radiotherapy treatment compared to patients with an axillary lymph node dissection. It is suggested that irradiation of the shoulder tissue leads to decreased mobility. The ESTRO consensus guideline for target delineation for elective breast and nodal radiotherapy establishes the humeral head and connective tissues 10 mm around it as planning risk volume (PRV) .
Tangential fields are widely used for breast radiotherapy [8–11]. Modified high tangential fields (HTF) have been proposed to ensure coverage of the level I and II lymph nodes [12, 13]. Ohashi et al. extended the tangential fields in the cranial and posterior direction to include level I—III lymph nodes , while Alco et al. extended the cranial and posterior border to include level I and II lymph nodes . IMRT techniques for breast radiotherapy emerged over the past years due to the improved dose homogeneity and target coverage compared to HTF [9, 14–16]. Dogan et al. concluded that sparing of the humeral head while maintaining target coverage is best achieved with a 9-field IMRT technique for the whole breast with internal mammary nodes, supraclavicular and axillary lymph nodes . More recently, VMAT techniques have been explored for breast radiotherapy due to the improved dose homogeneity and target coverage compared to HTF and IMRT for whole breast radiotherapy. While reducing hotspots (dose > 107%) in the PTV and high doses in organs at risk (OAR), larger low dose regions in OARs have been reported [15, 17–19]. Osman et al. found improved target coverage, conformity and reduced lung doses when comparing VMAT with 3D conformal radiotherapy plans for the breast, internal mammary node and periclavicular lymph nodes . However, the average dose to the contralateral breast increased when using VMAT.
The aim of this planning study was to assess the dose to the humeral head PRV with the currently used HTF. If this dose is too high, the influence of the humeral head sparing on the coverage of target volumes with HTF is determined. Finally, the optimal technique for humeral head sparing in elective breast radiotherapy including level I and II lymph nodes will be determined by comparing different planning techniques.
Patients and equipment
Ten consecutive patients with left-sided breast cancer previously treated at our institute were enrolled in a planning study performed in Pinnacle3 (v9.8; Philips). This patient dataset reflects the variations in the irradiated anatomy in our patient population well. Treatment planning of left-sided breast radiotherapy is more challenging due to the proximity of the heart to the treatment volume and increased heart dose compared to right-sided breast radiotherapy. Voluntary breath hold is state of the art for left-sided breast radiotherapy to reduce the heart dose  and was used during treatment of all ten patients.
Treatment planning techniques
High tangential field (HTF)
HTF with sparing of the humeral head
6-field IMRT with sparing of the humeral head
VMAT with sparing of the humeral head
Initial set of objectives used for the inverse optimization
Region of Interest
For 6-field IMRT and VMAT with sparing of the humeral head:
All techniques were planned with 6 MV photon beams. For the HTF, the cranial and posterior border of the tangential fields was extended to include PTVn. The maximum number of segments was 8 with a minimum area of 9 cm2 and a minimum of 4 MU per segment. The collimator angle was 0 degree. These setting were the same for HTF with and without sparing of the humeral head. The plan was optimized with the initial objectives of Table 1 to fulfil the previously mentioned evaluation criteria for PTV coverage and minimized OAR doses. For HTF with sparing of the humeral head, the leaves of the 10 mm MLC were then manually closed to exclude hh+10 and reduce the dose to the humeral head and surrounding tissue.
The fourth technique was a VMAT dual arc from around 310 to 180 degrees with control points every 4 degrees. In the optimization parameters, the maximum delivery time was 60 s per arc. The minimum segment area was 6 cm2 and the collimator was rotated 10 degree to minimize tongue-and-groove effects.
Dose parameters were recorded for each plan. V90% and V95% of PTVp and PTVn were obtained, as well as the average dose to the lungs, heart, the contralateral breast and the V40Gy of hh+10. The conformity indices CI95% and CI90% were calculated as the ratio between the volume of the 95% or 90% isodose and the total PTV. Dose parameters of two planning techniques were tested for statistical significance with a paired two-tailed Wilcoxon signed rank sum test in Excel. It was corrected for multiple testing with the Bonferroni method (n = 4) and differences were considered significant when p ≤ 0.0125. In addition, the volume overlap between hh+10 and the PTVtotal was measured. In a sub-analysis, it was investigated whether the overlap between these two structures could indicate which patient benefits from a humeral head sparing technique and which could be treated properly with the current standard of HTF (see Appendix).
Dose parameters for the PTVs and OARs for all four techniques
HTF hh –
HTF hh – VMAT p-value
PTVp V90% (%)
PTVp V95% (%)
PTVn V90% (%)
PTVn V95% (%)
Lungs Dmean (Gy)
Heart Dmean (Gy)
Contralat. breast Dmean (Gy)
hh+10 V40Gy (cc)
A single patient out of ten met the constraint for hh+10 with HTF. This patient was also the only patient that did not have an overlap between hh+10 and the total PTV. The overlap was on average 2.1 cc (0–5.1 cc).
In case of elective breast radiotherapy including the axillary levels I and II, we compared four planning techniques and evaluated the coverage of the PTVs and the OARs. We found that 6-field IMRT with sparing of the humeral head resulted in the best coverage of PTVp and PTVn while not increasing the dose to the lungs, heart and contralateral breast compared to HTF.
The coverage of PTVn was increased significantly with the 6-field IMRT technique compared to the HTF. Dogan et al. treated the whole breast and the internal mammary node, supraclavicular and axillary lymph nodes with a 6-field IMRT technique and achieved a D95% of 50.2 ± 0.8 Gy to the axillary lymph nodes with a prescription dose of 50 Gy in 25 fractions . With a 2-field IMRT approach similar to our HTF, this was 49.8 ± 0.8 Gy. However, sparing of the humeral head was not achieved with these techniques. In our study, the most optimal sparing of the humeral head was achieved with the 6-field IMRT, which is similar to their 6-field IMRT technique, and VMAT technique while still meeting the constraints for lymph node coverage. Dogan et al. mentioned treatment complexity as one of the factors for choosing 2- and 4-field IMRT as optimal techniques. Currently, treatment complexity (i.e. number of IMRT beams) is no longer a limiting factor.
Alco et al. recorded a V95% of 94.4% (85.3–98.7%) in level I and 90.1% (80.6–94.4%) in level II lymph nodes with modified HTF . The tangential fields were modified to extend just until the inferior border of the humeral head and the MLCs were manipulated to include the level I and II lymph nodes. Alco et al. did not spare the humeral head. We found a lower PTVn V95% with the two HTF techniques, but when using 6-field IMRT and VMAT the V95% improved. With the more advanced 6-field IMRT and VMAT technique including sparing of the humeral head, our PTVn V95% was comparable to Alco et al. with IMRT and better than Alco et al. with VMAT.
Ohashi et al. reported level I and II V90% of 97.6% (96.0–99.2%) and 89.5% (84.2–93.2%) with modified HTF . Their HTF technique was similar to Alco et al. and did also not spare the humeral head. In our study, PTVn coverage with HTF is higher (average V90% 97.9%, range 96.6–99.3), but decreased to an inacceptable level when sparing the humeral head. Again, the more advanced IMRT and VMAT techniques reached the same or better coverage compared to Ohashi et al. while sparing the humeral head.
Belkacemi et al. concluded that HTF did not result in adequate coverage of the level I and II lymph nodes . They extended the cranial border of the tangential fields until the inferior border of the humeral head similar to Ohashi et al. and Alco et al., but did not extend the posterior field border. In our experience, the cranial and posterior part of the lymph nodes can extend beyond the caudal border of the humeral head in the tangential fields and therefore be outside the treatment field. In our study, the cranial and posterior border of the HTF was based on the dimensions of PTVn and resulted in sufficient PTVn coverage. PTVn coverage decreased significantly when sparing the humeral head by closing the MLC due to the overlap between PTV and hh+10; particularly a too low dose in level II (see Table 2 and Fig. 3b).
Dogan et al. concluded that high doses in the heart can be reduced with IMRT techniques while maintaining excellent coverage of the breast and regional nodes . Schubert et al.  compared different planning techniques for the whole breast and reported the following OAR dose parameters with an inverse IMRT technique: Dmean heart 1.9 ± 0.8 Gy and Dmean contralateral breast 0.3 ± 0.1 Gy. With tomotherapy, these parameters were 3.9 ± 1.3 Gy and 0.6 ± 0.1 Gy, respectively. We found slightly larger average doses to the heart and contralateral breast (Table 2) due to the increased treatment volume when axillary lymph nodes are involved. When comparing the four techniques, the differences between the mean dose to the heart and contralateral breast are often statistically significant. However, the differences are very likely in most cases not clinically relevant except for the increase in contralateral breast dose when comparing IMRT and VMAT. Osman et al. also found a similar increase in contralateral breast dose when using VMAT (Dmean on average 2.7 Gy) compared to forward planned IMRT (Dmean on average 0.7 Gy) when treating the breast, internal mammary node and periclavicular lymph nodes .
When comparing these planning studies, it has to be noted that lymph node contouring may have been based on different contouring guidelines. The ESTRO guideline by Offersen et al.  focusses on the delineation of level I—IV lymph nodes and has been used in this planning study. In addition, contouring is prone to variabilities and even when the same guideline is followed, its interpretation can vary . A PRV of the humeral head with a margin of 10 mm is defined by Offersen et al. , but no dose constraints are indicated.
Data on the dose to the humeral head and surrounding tissue during breast radiotherapy is scarce. In our planning study we restricted the high dose to hh+10. Dogan et al. based their constraint of a maximum dose of 40 Gy on their clinical experience with head and neck cancer .
As there is no consensus yet which DVH parameters for the humeral head PRV are clinically most relevant, we have also recorded Dmin, Dmean, Dmax, D0.5cc, D2%, D98% and V50% (see Appendix Table 3). Ideally, this constraint should be based on data correlating the change in shoulder mobility to the dose in the shoulder tissue. To the best of our knowledge, there is no literature on a dose-effect relationship for the shoulder tissue and the shoulder mobility. Delineation and dose assessment of the shoulder muscles should be further investigated but is outside the scope of this article.
The humeral head is rarely spared when using conventional high tangential fields. It is not possible to spare the humeral head with HTF without reducing lymph node coverage of level I and II. The humeral head and surrounding tissues can be spared with the 6-field IMRT and VMAT technique without reducing PTVn coverage. The 6-field IMRT technique does not increase the dose to the OARs compared to HTF, while the VMAT technique leads to a higher dose in the contralateral breast.
Humeral head + 10 mm
High tangential fields
Organs at risk
Planning risk volume
Planning target volume of the level I and II lymph nodes
Planning target volume of the breast
Availability of data and materials
The authors do not wish to share the data as the data is in Dutch and might be misinterpreted. Upon individual request, we can share the data and give an explanation to it.
KS and CH drafted the manuscript. All authors participated in the design of the presented study. KS, JL, TB and ML performed the study. All authors read and approved the final manuscript.
The authors declare that they have no competing interest.
Consent for publication
Ethics approval and consent to participate
This research was judged by the METC of the Catharina Hospital as not needing a registration according to the WMO (Dutch law on medical research).
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
- Donker M, van Tienhoven G, Straver ME, et al. Radiotherapy or surgery of the axilla after a positive sentinel node in breast cancer (EORTC 10981-22023 AMAROS): a randomised, multicentre, open-label, phase 3 non-inferiority trial. Lancet Oncol. 2014;15:1303–10.View ArticlePubMedPubMed CentralGoogle Scholar
- Giuliano AE, McCall L, Beitsch P, et al. Locoregional recurrence after sentinel lymph node dissection with or without axillary dissection in patients with sentinel lymph node metastases: the American College of Surgeons Oncology Group Z0011 randomized trial. Ann Surg. 2010;252:426–32.PubMedGoogle Scholar
- Blomqvist L, Stark B, Engler N, Malm M. Evaluation of arm and shoulder mobility and strength after modified radical mastectomy and radiotherapy. Acta Oncol. 2004;43:280–3.View ArticlePubMedGoogle Scholar
- Johansen J, Overgaard J, Blichert-Toft M, Overgaard M. Treatment of morbidity associated with the management of the axilla in breast-conserving therapy. Acta Oncol. 2000;39:349–54.View ArticlePubMedGoogle Scholar
- Johansen S, Fossa K, Nesvold IL, Malinen E, Fossa SD. Arm and shoulder morbidity following surgery and radiotherapy for breast cancer. Acta Oncol. 2014;53:521–9.View ArticlePubMedGoogle Scholar
- Nesvold IL, Dahl AA, Lokkevik E, Marit MA, Fossa SD. Arm and shoulder morbidity in breast cancer patients after breast-conserving therapy versus mastectomy. Acta Oncol. 2008;47:835–42.View ArticlePubMedGoogle Scholar
- Offersen BV, Boersma LJ, Kirkove C, et al. ESTRO consensus guideline on target volume delineation for elective radiation therapy of early stage breast cancer. Radiother Oncol. 2015;114:3–10.View ArticlePubMedGoogle Scholar
- Jagsi R, Chadha M, Moni J, et al. Radiation field design in the ACOSOG Z0011 (Alliance) Trial. J Clin Oncol. 2014;32:3600–6.View ArticlePubMedPubMed CentralGoogle Scholar
- Schubert LK, Gondi V, Sengbusch E, et al. Dosimetric comparison of left-sided whole breast irradiation with 3DCRT, forward-planned IMRT, inverse-planned IMRT, helical tomotherapy, and topotherapy. Radiother Oncol. 2011;100:241–6.View ArticlePubMedGoogle Scholar
- Zhang L, Yang ZZ, Chen XX, et al. Dose coverage of axillary level I-III areas during whole breast irradiation with simplified intensity modulated radiation therapy in early stage breast cancer patients. Oncotarget. 2015;6:18183–91.View ArticlePubMedPubMed CentralGoogle Scholar
- Belkacemi Y, Lab-Pan Q, Bigorie V, et al. 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. AnnOncol. 2013;24:2023–8.Google Scholar
- Alco G, Igdem SI, Ercan T, et al. Coverage of axillary lymph nodes with high tangential fields in breast radiotherapy. Br J Radiol. 2010;83:1072–6.View ArticlePubMedPubMed CentralGoogle Scholar
- Ohashi T, Takeda A, Shigematsu N, et al. Dose distribution analysis of axillary lymph nodes for three-dimensional conformal radiotherapy with a field-in-field technique for breast cancer. Int J Radiat Oncol Biol Phys. 2009;73:80–7.View ArticlePubMedGoogle Scholar
- Dogan N, Cuttino L, Lloyd R, Bump EA, Arthur DW. Optimized dose coverage of regional lymph nodes in breast cancer: the role of intensity-modulated radiotherapy. Int J Radiat Oncol Biol Phys. 2007;68:1238–50.View ArticlePubMedGoogle Scholar
- Osman SO, Hol S, Poortmans PM, Essers M. Volumetric modulated arc therapy and breath-hold in image-guided locoregional left-sided breast irradiation. Radiother Oncol. 2014;112:17–22.View ArticlePubMedGoogle Scholar
- Sethi RA, No HS, Jozsef G, Ko JP, Formenti SC. Comparison of three-dimensional versus intensity-modulated radiotherapy techniques to treat breast and axillary level III and supraclavicular nodes in a prone versus supine position. Radiother Oncol. 2012;102:74–81.View ArticlePubMedGoogle Scholar
- Jin GH, Chen LX, Deng XW, Liu XW, Huang Y, Huang XB. A comparative dosimetric study for treating left-sided breast cancer for small breast size using five different radiotherapy techniques: conventional tangential field, filed-in-filed, tangential-IMRT, multi-beam IMRT and VMAT. Radiat Oncol. 2013;8:89.View ArticlePubMedPubMed CentralGoogle Scholar
- Johansen S, Cozzi L, Olsen DR. A planning comparison of dose patterns in organs at risk and predicted risk for radiation induced malignancy in the contralateral breast following radiation therapy of primary breast using conventional, IMRT and volumetric modulated arc treatment techniques. Acta Oncol. 2009;48:495–503.View ArticlePubMedGoogle Scholar
- Viren T, Heikkila J, Myllyoja K, Koskela K, Lahtinen T, Seppala J. Tangential volumetric modulated arc therapy technique for left-sided breast cancer radiotherapy. Radiat Oncol. 2015;10:79.View ArticlePubMedPubMed CentralGoogle Scholar
- Shah C, Badiyan S, Berry S, et al. Cardiac dose sparing and avoidance techniques in breast cancer radiotherapy. Radiother Oncol. 2014;112:9–16.View ArticlePubMedGoogle Scholar
- Feng M, Moran JM, Koelling T, et al. Development and validation of a heart atlas to study cardiac exposure to radiation following treatment for breast cancer. Int J Radiat Oncol Biol Phys. 2011;79:10–8.View ArticlePubMedGoogle Scholar
- Offersen BV, Boersma LJ, Kirkove C, et al. ESTRO consensus guideline on target volume delineation for elective radiation therapy of early stage breast cancer, version 1.1. Radiother Oncol. 2016;118:205–8.View ArticlePubMedGoogle Scholar