Consensus Statement on Tumour Bed Localization for Radiation after Oncoplastic Breast Surgery

Abstract

Background: Oncoplastic surgery (OPS) is becoming the new standard of care for breast-conserving surgery. OPS has led to some challenges with adjuvant radiation, particularly when accurate tumour bed (TB) delineation is needed for focused radiation (i.e. accelerated partial breast radiation or boost radiation). Currently, there on no guidelines on tumour bed localization for adjuvant targeted radiation after OPS.
 Methods: A modified-Delphi method was used to establish consensus amongst a panel of 20 experts in surgical and radiation oncology at the Canadian Locally Advanced Breast Cancer National Consensus (LABCNC) Group and in subsequent online surveys.
 Results: The main recommendations are as follows: 1) Surgical clips are necessary and should, at a minimum, be placed along the four side walls of the cavity plus one to four clips at the posterior margin if necessary; 2) Operative reports should include pertinent information to help guide the radiation oncologists; 3) Breast surgeons and radiation oncologists should have a basic understanding of OPS techniques and work on “speaking a common language”; and 4) Careful consideration is needed when determining the value of targeted radiation, like boost, in higher level OPS procedures with extensive tissue rearrangement.
 Conclusion: The panel developed a total of six recommendations on TB delineation for more focused radiation therapy after OPS, with over 80% agreement on each statement. These are summarized along with the corresponding evidence and/or expert opinion.

Partial Breast Irradiation and Surgical Clip Usage for Tumor Bed Delineation After Breast-Conserving Surgery in Canada: A Radiation Oncology Perspective

“…These findings informed the British surgical guidelines for the management of breast cancer with regard to the marking of the surgical bed with clips during breastconserving surgery to facilitate breast radiotherapy [24]. The optimal placement and number of surgical clips following breast-conserving surgery have also been described to assist in the delivery of external beam radiotherapy for WBI, PBI or boost [25][26][27]. These guidelines and basic principles regarding consistent marking of the tumor bed with clips are becoming increasingly important for breast radiotherapy due to the frequent use of oncoplastic procedures in contemporary breast conservation techniques, whereby the tumor bed is typically poorly visualized in the post-operative setting [28].…”

“…With the increasing use of surgical techniques that minimize clear visualization of the tumor bed, the consistent placement of surgical clips is becoming even more important for breast radiotherapy, particularly for PBI and boost. To address this issue, specific recommendations have included: the consistent placement of 4-6 clips in the walls of the surgical cavity at the level where the primary tumor was located representing the boundaries of the resection; insertion of clips prior to repositioning or rotation of breast tissue during oncoplastic procedures; detailed operative reports that include the number of clips used, clip placement and closure technique; and close multidisciplinary collaboration between surgeons and radiation oncologists to augment reliable and accurate localization of the tumor bed for breast radiotherapy planning [23,27,28].…”

“…While PBI typically minimizes normal tissue toxicity compared to WBI, the Canadian RAPID trial [11] reported increased late toxicity with the PBI regimen of 38.5Gy in 10 fractions delivered twice daily over 1 week, predominantly due to increased grade 2 induration or fibrosis [11]. Therefore, there are also ongoing prospective phase 2 studies in Canada evaluating other PBI regimens, including 27Gy in 5 daily fractions (NCT02681107) [14], and 30Gy vs. 27.5Gy in 5 daily fractions (NCT02637024). In contrast, the NSABP B-39/RTOG 0413 trial, which evaluated the same PBI regimen used in the RAPID trial, reported similar late treatment-related toxicities for WBI and PBI [13].…”

“…24 The optimal placement and number of surgical clips after breast-conserving surgery have also been described to assist in the delivery of external beam RT for WBI, PBI, or boost. 25 , 26 , 27 These guidelines and basic principles regarding consistent marking of the tumor bed with clips are becoming increasingly important for breast RT due to the frequent use of oncoplastic procedures in contemporary breast conservation techniques, whereby the tumor bed is typically poorly visualized in the postoperative setting. 28 It is estimated that 32% (21,388/67,878) of women diagnosed with breast cancer in England between the years 2012 to 2016 were eligible for PBI 29 ; therefore, clear visualization of the tumor bed after breast-conserving surgery is essential to maximize local therapy options for a sizeable proportion of patients with breast cancer with low-risk disease.…”

Breast Radiotherapy after Oncoplastic Surgery—A Multidisciplinary Approach

“…While not always achievable, the consensus panel suggests that surgeons attempt to be present with the radiation oncologists during target contouring and radiation boost planning. Through such partnerships, the challenge of translating geometric information from one medical specialty to another for the optimal treatment of the patient can be overcome [ 62 ].…”