Volume 61, December 2022, 152060AbstractBackground

Pathologic examination of post-neoadjuvant chemotherapy (NAC) breast surgical specimens includes assessment of margins. It has been recommended that tumor bed (TB) changes extending to margins should be documented; however, its' incidence and clinical significance have not yet been established. The aim of our study was to gather prognostic data on this histological finding.

Design

We retrospectively identified all cases where TB was reported at margin. Cases where margins were also positive for invasive carcinoma or DCIS were excluded.

Results

From 2016 to 2019, 115 cases of NAC treated breast cancers were identified with 21 having at least one margin positive for TB after initial surgery (incidence of 18.3 %). Five cases were estrogen receptor (ER)-/HER2-, 9 were HER2+ and 7 were ER+/HER2-. Nineteen patients underwent partial mastectomy and 2 underwent total mastectomy. Nine patients had a pathological complete response (pCR).Ten cases had more than one positive margin for TB. None of the 21 patients underwent a second surgery for margin re-excision. Twenty patients received adjuvant therapy. With an average follow-up of 28.1 months, there has been one local recurrence. Four other patients developed metastatic disease, one of which died of the disease. The rates of locoregional and distant recurrence and mortality were statistically similar to those from patients whose margins were negative for TB.

Conclusions

Our results suggest low risk of local recurrence when a positive margin for TB is not re-excised. Further data and follow-up will be needed to confirm the adequacy of conservative management in this setting.

Introduction

Neoadjuvant chemotherapy (NAC) is increasingly used in the treatment of breast cancer. Although the timing of systemic therapy (pre-operative versus post-operative) does not alter overall survival or disease-free survival, valuable information can be deduced from the response of the cancer to neoadjuvant treatment [1]. Response to treatment offers prognostic information and allows insight into tumor biology. In order to standardize pathologic assessment of breast cancer specimens after NAC, guidelines have been published regarding specimen handling and microscopic reporting [2], [3], [4], [5]. As in the non-neoadjuvant setting, microscopic involvement of surgical margins by invasive or in situ carcinoma should be reported. The latest consensus guidelines on margins for breast conserving surgery (BCS) showed that positive margin (ink on tumor) is associated with at least a 2-fold increase in ipsilateral breast tumor recurrence [6]. However, patients treated with NAC were excluded from this study. In general, the “no tumor on ink” principle has been applied to post-NAC specimens, with few studies supporting this approach as safe regarding disease free survival and overall survival [7], [8]. In addition, for post-NAC specimens, it has been recommended that tumor bed (TB) changes extending to margins should be documented in the pathology report [2], [3], [4], [5]. When invasive carcinoma regresses following NAC, a scar, where invasive carcinoma previously was, can be identified histologically, which corresponds to the TB. To our knowledge, no study has reported the incidence nor the clinical significance of TB extending to surgical margins. Thus, the aim of our study was to gather prognostic data on this histological finding.

Section snippetsMaterials and methods

After this study received institutional review board approval, all pathology reports on patients with breast carcinoma undergoing surgery after NAC at our institution between August 2016 and May 2020 were reviewed. TB at margins has been routinely mentioned in the pathology reports at our institution since August 2016. Cases were included if TB was reported at margins, which was defined as TB on ink (Fig. 1). This finding was subsequently confirmed by slide review by a breast pathologist. Cases

Results

Over a forty-six-month period (August 2016–May 2020), 115 patients with breast carcinoma treated with NAC underwent surgery at our institution. Of these patients, 26 had margins positive solely for TB. Complete re-excision of all TB positive margins by cavity shave margins during initial surgery was performed in 5 cases: four cases had no additional findings in the new shave cavity margins, and one case had DCIS. None of these 5 cases had TB changes in the shave cavity margins. Thus, after

Discussion

NAC chemotherapy is increasingly used in the treatment of breast cancer. One of the advantages of NAC is downstaging tumors, either rendering a non-operable breast cancer operable or permitting BCS in a patient who would otherwise require a total mastectomy. In a study, 75 % of BCS-ineligible patients were converted to BCS candidates with NAC [13]. Moreover, for patients who were already candidates for BCS, NAC can reduce the volume of excision specimens, potentially improving cosmetic outcome,

Conclusion

In conclusion, margins positive solely for TB in the post-NAC setting is not an uncommon finding, as shown by the incidence of 18 % in our study. Our results suggest LRR remains low in this setting, and that additional surgery to obtain margins clear of TB may not be warranted. More data and longer follow-up will be needed to draw conclusions on the clinical significance of TB at margin and confirm the safety of foregoing margin re-excision, as this is, to our knowledge, the first study

Source of funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of competing interest

None to declare.

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