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BRIEF COMMUNICATION
Year : 2020  |  Volume : 16  |  Issue : 6  |  Page : 1522-1523

Contouring for radiotherapy in carcinoma breast – why a robust uniform guideline is (nearly) impossible


Department of Radiation Oncology, Manipal Hospital, Dwarka, New Delhi, India

Date of Submission15-Jul-2019
Date of Acceptance01-Dec-2019
Date of Web Publication26-Nov-2020

Correspondence Address:
Anusheel Munshi
Department of Radiation Oncology, Manipal Hospital, Dwarka - 110 075, New Delhi
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jcrt.JCRT_499_19

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How to cite this article:
Munshi A. Contouring for radiotherapy in carcinoma breast – why a robust uniform guideline is (nearly) impossible. J Can Res Ther 2020;16:1522-3

How to cite this URL:
Munshi A. Contouring for radiotherapy in carcinoma breast – why a robust uniform guideline is (nearly) impossible. J Can Res Ther [serial online] 2020 [cited 2021 Nov 27];16:1522-3. Available from: https://www.cancerjournal.net/text.asp?2020/16/6/1522/301000



While contouring guidelines for many body sites have emerged and achieved acceptance in the past few years, a uniform breast contouring practice has never taken off.[1],[2] In a relevant study representing eight institutions, breast contouring volume variations had standard deviations up to 60%.[3] In another study involving 15 centers and 42 radiation oncologists, less than half of the centers could claim to have a good agreement between the internal radiation oncologists for contouring axilla.[4]

Various factors contribute to high variability in breast contouring across individual practitioners and centers. For most body sites, there is a standard position for radiotherapy simulation and treatment. The breast remains a site where one can adopt prone or supine simulation (or a lateral position for giving boost). These positional variations in simulation can affect target and organs at risk doses.[5],[6]

Breast volume is a possible determinant in breast contouring landmarks. Variation in breast contour in the population is significant. In a study of 30 patients scheduled for total mastectomy, the mean mastectomy specimen volume was 623.5 ml, with a range (as variable as) of 150–1490 ml.[7] Whether this variation in breast volume correlates and is proportionate with other bony/soft-tissue landmarks used for contouring has never been studied.

For whole breast or chest wall radiotherapy, the dorsal boundary again lacks consensus. The dorsal boundary could be (a) anterior aspect of pectoralis major (the European Society for Radiotherapy and Oncology) and (b) anterior pleural surface (the Radiation Therapy Oncology Group) or anterior rib surface as is practiced at some institutions.[8],[9] The cranial boundary of the breast again is a fluctuating line, depending whether or not a supraclavicular field is used. The lateral edge of the breast is perhaps the most subjective of all boundaries because of the merging of breast tissue with the fatty tissue laterally. Whether the contoured breast volume should be 2 mm, 3 mm or 5 mm inside the skin (on the anterior side) is again a matter of debate.

Contouring for the boost volume after whole breast radiotherapy can be equally challenging. There is hardly any consensus on whether to take ultrasonography assistance, to do computed tomography (CT) or magnetic resonance imaging, or to use surgically placed clips during contouring of the cavity. Cavity shape itself could change depending on the timing of radiation (immediately after surgery versus postsurgery and postchemotherapy).[10],[11] Even after delineation of cavity/tumor bed, there is a lack of consensus about clinical target volume (margin for microscopic disease) needed. Conventionally, the margin beyond the cavity was 1–1.5 cm. However, trials like TARGIT using intrabeam have used which use only 1 mm margin to the cavity site, challenging the long-standing larger margins that were used for boost/tumor bed delineation.[12],[13]

Regional nodal irradiation contouring is even more controversial. An emerging consensus is treating only “undissected axilla” with radiotherapy. However, CT simulation scans at the time of radiotherapy do not allow ready discrimination of the “undissected axilla.” The extent of supraclavicular fields and issues in contouring for internal mammary radiotherapy are other areas of concern.[14]

No wonder then, that breast radiation oncology clinicians and researchers globally have occasionally expressed the feelings of despair with respect to breast contouring.[15] Unfortunately for the numerous patients of breast cancer undergoing irradiation, this lack of concordance in contouring shall prevail across individuals and across centers (and across guidelines!).

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 > References Top

1.
Lim K, Small W Jr., Portelance L, Creutzberg C, Jürgenliemk-Schulz IM, Mundt A, et al. Consensus guidelines for delineation of clinical target volume for intensity-modulated pelvic radiotherapy for the definitive treatment of cervix cancer. Int J Radiat Oncol Biol Phys 2011;79:348-55.  Back to cited text no. 1
    
2.
Brouwer CL, Steenbakkers RJ, Bourhis J, Budach W, Grau C, Grégoire V, et al. CT-based delineation of organs at risk in the head and neck region: DAHANCA, EORTC, GORTEC, HKNPCSG, NCIC CTG, NCRI, NRG Oncology and TROG consensus guidelines. Radiother Oncol 2015;117:83-90.  Back to cited text no. 2
    
3.
Li XA, Tai A, Arthur DW, Buchholz TA, Macdonald S, Marks LB, et al. Variability of target and normal structure delineation for breast cancer radiotherapy: An RTOG Multi-Institutional and Multiobserver Study. Int J Radiat Oncol Biol Phys 2009;73:944-51.  Back to cited text no. 3
    
4.
Ciardo D, Argenone A, Boboc GI, Cucciarelli F, De Rose F, De Santis MC, et al. Variability in axillary lymph node delineation for breast cancer radiotherapy in presence of guidelines on a multi-institutional platform. Acta Oncol 2017;56:1081-8.  Back to cited text no. 4
    
5.
Thompson G, Lavigne F, Dimascio M, Bohorquiz C, Lamba M. Axillary lymph node coverage of tangent radiotherapy. Comparison of supine versus prone positioning. J Clin Oncol 2017;30 Suppl 200:27.  Back to cited text no. 5
    
6.
Kawamura M, Maeda Y, Yamamoto K, Takamatsu S, Sato Y, Minami H, et al. Development of the breast immobilization system in prone setup: The effect of bra in prone position to improve the breast setup error. J Appl Clin Med Phys 2017;18:155-60.  Back to cited text no. 6
    
7.
Kayar R, Civelek S, Cobanoglu M, Gungor O, Catal H, Emiroglu M. Five methods of breast volume measurement: A comparative study of measurements of specimen volume in 30 mastectomy cases. Breast Cancer (Auckl) 2011;5:43-52.  Back to cited text no. 7
    
8.
Würschmidt F, Stoltenberg S, Kretschmer M, Petersen C. Incidental dose to coronary arteries is higher in prone than in supine whole breast irradiation. A dosimetric comparison in adjuvant radiotherapy of early stage breast cancer. Strahlenther Onkol 2014;190:563-8.   Back to cited text no. 8
    
9.
Pifer PM, Bice RP, Jacobson GM, Lupinacci K, Beriwal S, Hazard HW, et al. The lack of consensus of international contouring guidelines for the dorsal border of the chest wall clinical target volume: What is the impact on organs at risk and relationships to patterns of recurrence in the modern era? Adv Radiat Oncol 2019;4:35-42.  Back to cited text no. 9
    
10.
Offersen BV, Boersma LJ, Kirkove C, Hol S, Aznar MC, Sola AB, 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.  Back to cited text no. 10
    
11.
Nielsen MH, Berg M, Pedersen AN, Andersen K, Glavicic V, Jakobsen EH, et al. Delineation of target volumes and organs at risk in adjuvant radiotherapy of early breast cancer: National guidelines and contouring atlas by the Danish Breast Cancer Cooperative Group. Acta Oncol 2013;52:703-10.  Back to cited text no. 11
    
12.
Petersen RP, Truong PT, Kader HA, Berthelet E, Lee JC, Hilts ML, et al. Target volume delineation for partial breast radiotherapy planning: Clinical characteristics associated with low interobserver concordance. Int J Radiat Oncol Biol Phys 2007;69:41-8.  Back to cited text no. 12
    
13.
Vaidya JS, Joseph DJ, Tobias JS, Bulsara M, Wenz F, Saunders C, et al. Targeted intraoperative radiotherapy versus whole breast radiotherapy for breast cancer (TARGIT-A trial): An international, prospective, randomised, non-inferiority phase 3 trial. Lancet 2010;376:91-102.  Back to cited text no. 13
    
14.
Available from: https://www.nccn.org/professionals/physician_gls/default.aspx. [Last accessed on 2019 Feb 18].  Back to cited text no. 14
    
15.
Vargo JA, Beriwal S. In reply to Chang et al.: Contouring guidelines for post-mastectomy radiotherapy a cry for international consensus. Radiother Oncol 2017;123:483-4.  Back to cited text no. 15
    




 

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