Prognostic factors for residual occult disease in shave margins during partial mastectomy

PURPOSE

Shave margins have been shown to decrease positive final margins in partial mastectomy. We investigated prognostic factors associated with residual disease in shave margins.

METHODS

Patients with invasive breast carcinoma and ductal carcinoma in situ (DCIS) who had circumferential shave margins excised during lumpectomy were abstracted from a retrospective database from 2015 to 2018. We defined residual occult disease (ROD) as either (1) residual disease in a shave margin when the initial lumpectomy specimen had negative margins or (2) residual disease in a shave margin that did not correspond with the positive lumpectomy margin. We identified the frequency of ROD and conducted logistic regression analysis to identify associated prognostic factors.

RESULTS

166 Patients (139 invasive carcinoma, 27 DCIS) were included with median follow-up of 28 months (9-50 months). Residual occult disease existed in 34 (24.5%) with invasive carcinoma and 8 (29.6%) with DCIS. In univariate analyses of the invasive group, invasive lobular carcinoma and a positive initial, non-corresponding lumpectomy margin were predictive of ROD (OR 3.63, p = 0.04, OR 3.48, p = 0.003 respectively). In multivariate analysis, a positive lumpectomy margin remained significant, p = 0.007. No variables were associated with ROD in DCIS.

CONCLUSION

Residual occult disease was shown to be a frequent event in this analysis of lumpectomy with circumferential shave margins. Having a positive initial lumpectomy margin was predictive of ROD in a non-corresponding margin. Surgeons should consider not being selective in their shave margins or margin of re-excision if shave margins were not obtained in their initial surgery.

Risk factors for the presence of residual disease in women after partial mastectomy for invasive breast cancer: A single institution experience

BACKGROUND

We hypothesize that in addition to specimen margin widths other clinical variables may help predict the presence of residual disease in the lumpectomy bed.

METHODS

Patients with Stage I-III invasive breast cancer (BC) who underwent partial mastectomy (PM) and re-excision from July 2010-June 2015 were retrospectively reviewed. Bivariate analyses were conducted using two-sample t-tests for continuous variables and Fisher's Exact tests for categorical variables. A multivariate logistic regression was then performed on significant bivariate analyses variables.

RESULTS

ne-hundred and eighty-four patients were included in our analysis; 47% had residual disease on re-excision, while 53% had no residual disease. Tumor and nodal stage, operation type, type of disease present at margin, and number of positive margins were significantly associated with residual disease. On multivariate logistic regression, DCIS alone at the margin (p = 0.02), operation type (PM with cavity margins) (p = 0.003), and number of positive margins (3 or more) (p < 0.001) remained predictive of residual disease at re-excision.

CONCLUSION

Based on a more comprehensive review of the initial pathology, there are additional factors that can help predict the likelihood of finding residual disease and help guide the surgeon in the decision for re-excision.

Surgical management of ductal carcinoma in situ of the breast: A large retrospective study from a single institution

BACKGROUND

Management of breast ductal carcinoma in situ (DCIS) has various approaches with distinct institutional specific practice. Here, we review DCIS management in a single institution with emphasize on re-operation rates and outcome.

METHODS

Breast ductal carcinoma in situ cases diagnosed at the Nottingham Breast Institute between 1987 and 2017 were identified (n = 1249). Clinicopathological data were collected. Cases were histologically reviewed, and different factors associated with primary operation selection, re-excision, presence of residual tumor in the re-excision specimens, use of radiotherapy and ipsilateral recurrences were analyzed.

RESULTS

34% of DCIS patients were initially treated by mastectomy and were more frequently symptomatic, of high nuclear tumor grade, size >40 mm, and associated with comedo necrosis and Paget's disease of the nipple. Further surgery was due to involved or narrow surgical margins. Residual tumor tissue was detected in 53% of the re-excision specimens. Re-excision rates of patients treated with breast-conserving surgery (BCS) were reduced from approximately 70% to 23%, and the final mastectomy rates decreased from 60% to 20%. Changes in surgical practice with acceptance of smaller excision margins and more frequent use of local radiotherapy have led to a significant decrease not only in the re-excision rate but also in the final mastectomy rate together with non-significant reduction in 5- and 10-year local recurrence rates.

CONCLUSION

Although BCS is increasingly the preferred primary surgical option for DCIS management, a proportion of low-risk DCIS patients continue to undergo re-excision surgery or completion mastectomy. Despite acceptance of smaller margins, recurrence rate is decreasing.

Re-excision rates after breast conserving surgery following the 2014 SSO-ASTRO guidelines

BACKGROUND

In 2014, SSO-ASTRO published guidelines which recommended "no ink on tumor" as adequate margins for patients undergoing breast conservation for invasive breast cancer. In 2016, new SSO-ASTRO-ASCO guidelines recommended 2 mm margins for DCIS. We evaluated whether these guidelines affected re-excision rates at our institution.

METHODS

Patients treated with breast conservation surgery from January 1, 2010-March 1, 2016 were identified. Re-excision rates, tumor characteristics, and presence of residual disease were recorded. The 2016 guidelines were retrospectively applied to the same cohort and expected re-excision rates calculated.

RESULTS

Re-excision rates did not significantly decline before and after 2014 guideline adoption (11.9% before, 10.9% after; p = 0.65) or when the 2016 guidelines were retrospectively applied (8.4%; p = 0.10).

CONCLUSIONS

The 2014 and 2016 guidelines had minimal impact on our re-excision rates, as most re-excisions were done for DCIS and 2016 guidelines supported our prior institutional practices of 2 mm margins for these patients.

A simulation framework for modeling tumor control probability in breast conserving therapy

BACKGROUND AND PURPOSE

Microscopic disease (MSD) left after tumorectomy is a major cause of local recurrence in breast conserving therapy (BCT). However, the effect of microscopic disease and RT dose on tumor control probability (TCP) was seldom studied quantitatively. A simulation framework was therefore constructed to explore the relationship between tumor load, radiation dose and TCP.

MATERIALS AND METHODS

First, we modeled total disease load and microscopic spread with a pathology dataset. Then we estimated the remaining disease load after tumorectomy through surgery simulation. The Webb-Nahum TCP model was extended by clonogenic cell fraction to model the risk of local recurrence. The model parameters were estimated by fitting the simulated results to the observations in two clinical trials.

RESULTS

Higher histopathology grade has a strong correlation with larger MSD cell quantity. On average 12.5% of the MSD cells remained in the patient's breast after surgery but varied considerably among patients (0-100%); illustrating the role of radiotherapy. A small clonogenic cell fraction was optimal in our model (one in every 2.7*10(6)cells). The mean radiosensitivity was estimated at 0.067Gy(-1) with standard deviation of 0.022Gy(-1).

CONCLUSION

A relationship between radiation dose and TCP was established in a newly designed simulation framework with detailed disease load, surgery and radiotherapy models.

Margin index: a useful tool for the breast surgeon?

BACKGROUND

In breast conservation surgery (BCS) for breast cancer, the appropriate surgical margin is controversial. Margin index, a mathematical relationship between tumor size and closest margin, has been shown to be predictive of the probability of residual cancer after BCS for early stage breast cancer. We applied this tool to the same population of patients at our institution to evaluate its ability to predict residual disease after BCS.

METHODS

We retrospectively reviewed a prospectively maintained database of women undergoing BCS between 1980 and 2010 at the University of Pennsylvania. A total of 246 women underwent re-excision because of close margins. Average margin index between groups with and without residual disease in the re-excision specimen was compared using the Student t-test. A receiver operating curve was created using logistic regression to assess the overall diagnostic ability of the margin index on the presence or absence of residual disease.

RESULTS

Of patients who underwent re-excision, 29% of patients had residual disease. We analyzed several cutoff values for margin index, but none proved to be significant predictors of residual disease. Average margin index was significantly higher for patients without residual disease compared with patients with residual invasive cancer but not for patients with residual ductal carcinoma in situ.

CONCLUSIONS

In women undergoing BCS for early stage breast cancer at our institution, margin index was not predictive of the presence of residual cancer on re-excision. We hypothesize that the predictive ability of a margin index is likely limited by several factors including the presence of ductal carcinoma in situ and the location and extent of the close margin.

Optimizing surgical margins in breast conservation

Adequate surgical margins in breast-conserving surgery for breast cancer have traditionally been viewed as a predictor of local recurrence rates. There is still no consensus on what constitutes an adequate surgical margin, however it is clear that there is a trade-off between widely clear margins and acceptable cosmesis. Preoperative approaches to plan extent of resection with appropriate margins (in the setting of surgery first as well as after neoadjuvant chemotherapy,) include mammography, US, and MRI. Improvements have been made in preoperative lesion localization strategies for surgery, as well as intraoperative specimen assessment, in order to ensure complete removal of imaging findings and facilitate margin clearance. Intraoperative strategies to accurately assess tumor and cavity margins include cavity shave techniques, as well as novel technologies for margin probes. Ablative techniques, including radiofrequency ablation as well as intraoperative radiation, may be used to extend tumor-free margins without resecting additional tissue. Oncoplastic techniques allow for wider resections while maintaining cosmesis and have acceptable local recurrence rates, however often involve surgery on the contralateral breast. As systemic therapy for breast cancer continues to improve, it is unclear what the importance of surgical margins on local control rates will be in the future.