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?

Abstract

PurposeVariation exists in cooperative group recommendations for the dorsal border for the chest wall clinical target volume (CTV). We aimed to quantify the impact of this variation on doses to critical organs and examine patterns of chest wall recurrence relative to the pectoralis muscle.Methods and MaterialsWe retrospectively assessed patterns of chest wall recurrence quantified to the recommended CTV borders for women treated between 2005 and 2017. We compared treatment plans for 5 women who were treated with left postmastectomy radiation therapy, with the chest wall contoured using varying dorsal borders for CTV: (1) Anterior pleural surface (Radiation Therapy Oncology Group), (2) anterior surface of pectoralis major (European Society for Radiotherapy and Oncology), and (3) anterior rib surface (institutional practice). Treatment plans were generated for 50 Gy in 25 fractions. Doses to organs-at-risk were compared using paired-sample t tests.ResultsInstitutional patterns of chest wall recurrence were 64.7% skin and subcutaneous tissue, 23.5% both anterior to and between the pectoralis muscles, and 11.8% isolated to the tissue between the pectoralis major and minor. No chest wall recurrences were noted deep to pectoralis minor. When comparing the plans generated per the Radiation Therapy Oncology Group versus European Society for Radiotherapy and Oncology contouring guidelines, the mean lung V20Gy, heart mean dose, and left anterior descending artery mean dose were 33.5% versus 29.4% (P < .01), 5.2 Gy versus 3.2Gy (P = .02), and 27.3Gy versus 17.8Gy (P = .04), respectively.ConclusionsThe recommended variations in the dorsal chest wall CTV border have significant impact on doses to the heart and lungs. Although our study was limited by small numbers, our institutional patterns of recurrence would support a more anterior dorsal border for the chest wall CTV consistent with older literature.

Spatial location of local recurrences after mastectomy: a systematic review

“…Considering the limits of the retrospective nature of the included studies and the heterogeneity of the disease stage, treatment and follow-up time, our results are consistent with the results published by Vargo et al, showing that most recurrences were isolated to tissues anterior to the pectoralis muscle. Additionally, Vargo et al reported that up to 23.5% of LRs are located both anterior to and between the pectoralis muscles, while only 11.8% were isolated to the tissue between the pectoralis major and minor (most probably a result of interpectoral nodal recurrence and not 'true' LR) [47,48]. Further studies are needed to analyse the location and timing according to the different types of mastectomy, reconstruction procedures and perioperative treatment.…”

Redefining postmastectomy radiation contouring in the era of immediate breast reconstruction: An accurate assessment of local recurrence risk

“…Full manuscripts could not be obtained or did not specify the location of recurrences in 74 publications. A total of 14 relevant articles were identified and were included in our meta-analysis [9][10][11][12][13][14][15][16][17][18][19][20][21][22].…”

“…The availability of acellular dermal matrix products has allowed for significant increases in one-stage immediate implant-based reconstruction [31], however concern regarding whether patients may require post-mastectomy chest wall radiation based on final pathological nodal status has led to conservative recommendations [10] 14 (200%) 0 0 14 Farras et al [11] 8 (80%) 2 (20%) 0 10 Gerber et al [12] 4 (66.7%) 0 2 (33.3%) 6 Gilliland et al [13] 50 (80%) 0 10 (20%) 60 Johnson et al [14] 7 (100%) 0 0 7 Meretoja et al [15] 8 (100%) 0 0 8 Noone et al [16] 12 (75.0%) 4 (25.0%) 0 (0%) 16 Pifer et al [17] 11 (64.7%) 6 (35.3%) 0 (0%) 17 Slavin et al [18] 17 (100%) 0 (0%) 0 (0%) 17 Sood et al [19] 6 (100%) 0 0 6 Stanec et al [20] 15 (100%) 0 0 15 Uriburu et al [21] 3 (100%) 0 0 3 Wang et al [22] 96 against immediate reconstruction in patients who may require radiation [32], despite improved cosmetic outcome and quality of life among patients who undergo immediate reconstruction at the time of their mastectomy [33].…”

A multidisciplinary view of mastectomy and breast reconstruction: Understanding the challenges

“…dorsal fascia was removed. As indicated above, per ACROP-ESTRO guidelines, in case of absence of tumour invasion into the pectoralis muscle, the pectoral muscle is not part of the CTV (Table 1) [1,7,51].…”

“…In any case, the final surgical and histopathological report should indicate if the pectoral dorsal fascia was removed. As indicated above, per ACROP-ESTRO guidelines, in case of absence of tumour invasion into the pectoralis muscle, the pectoral muscle is not part of the CTV ( Table 1 ) [ 1 , 7 , 51 ].

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