1. Breast conserving surgery (BCT): Every millimetre counts
Joint hospital surgical grand round
15/10/2016

2. Outline Background Surgical options Adequacy of margin
Invasive Ductal Carcinoma (IDC)
Ductal Carcinoma In Situ (DCIS)

3. Breast Cancer Background
Most common female cancer
Mean age of diagnosis 51.2
11.7% in situ cancers
93.8% ductal type
Hong Kong cancer fund statistics
Hong Kong Breast Cancer Registry report No. 7 issue 2015
14,400 patients

4. Surgical options
Mastectomy
Wide local excision + radiotherapy (BCT)

5. BCT: Adequacy of margin
Invasive ductal carcinoma
No ink on tumour
At least 2-fold increase risk in positive margins
Wider margin widths do not significantly lower risk of ipsilateral breast tumour recurrence (IBTR)
Not nullified by histological type, systemic therapy, mode of irradiation
Moran MS, Schnitt SJ, Giuliano AE, et al. (2014) Society of Surgical Oncology-American Society for Radiation Oncology consensus guideline on margins for breast-conserving surgery with whole-breast irradiation in stages I and II invasive breast cancer. J Clin Oncol 32:1507–1515

6. BCT: Adequacy of margin
Ductal carcinoma in situ (DCIS)
BCT + whole-breast radiation therapy (WBRT)
reduces rate of IBTR
10-year absolute risk reduction 15.2 %1
Non-significant difference in cancer-specific mortality2
1. Correa C, McGale P, Taylor C, et al. (2010) Overview of the randomized trials of radiotherapy in ductal carcinoma in situ of the breast. J Natl Cancer Inst Monogr 2010:162–177
2. Narod SA, Iqbal J, Giannakeas V. Breast Cancer Mortality After a Diagnosis of Ductal Carcinoma In Situ. JAMA Oncol doi: /jamaoncol

7. BCT: Adequacy of margin
Ductal carcinoma in situ (DCIS)
No consensus on what constitutes adequate margin
Re-excision:
Complications
Discomfort
Cosmetics
Costs

8. Pubmed Ductal carcinoma in situ, Breast conserving surgery, Margin
Systemic review / meta-analysis
14 results
Different conclusions
Threshold of 2mm as good as a wider margin1
Margin as wide as possible (greater than 10 mm)2
1. Dunne C, Burke JP, Morrow M. Effect of margin status on local recurrence after breast conservation and radiation therapy for ductal carcinoma in situ. J Clin Oncol Apr
2. Wang SY, Chu H, Shamliyan T et el. Network Meta-analysis of Margin Threshold for Women With Ductal Carcinoma In Situ. J Natl Cancer Inst Apr

9. Screen cap pubmed

10. Consensus guideline 2016 Journal of clinical oncology, 2016
Meta-analysis
20 retrospective studies
7883 DCIS patients
865 IBTR
Median follow-up 78.3 months
50 patients with DCIS treated with local excision >4 years follow-up

11. Guideline recommendations
A positive margin, defined as ink on DCIS, is associated with a significant increase in IBTR.
This increased risk is not nullified by the use of WBRT.
10-year IBTR rate 24% vs 12%
50% invasive recurrences

12. Guideline recommendations
Margins of at least 2 mm are associated with a reduced risk of IBTR relative to narrower margin widths in patients receiving WBRT.
The routine practice of obtaining negative margin widths wider than 2 mm is not supported by the evidence.
Statistically significant decrease IBTR for 2mm compared with 0 or 1mm (OR 0.51, P=0.01)
No significant differences in IBRT between 2mm, 3 or 5mm and 10mm margins threshold (P>0.40)
Marinovich ML, Azizi L, Macaskill P, et al. (in press) The association of surgical margins and local recurrence in women with ductal carcinoma in situ treated with breast-conserving therapy: A meta-analysis. Ann Surg Oncol

13. 2mm Margin width
Multi-focal DCIS, with gaps of uninvolved tissue between foci
Margin assessment limitations
Sampling, ex-vivo specimen, ink tracking
Selective re-excision for margins <2mm
Factors: (residual calcifications on postexcision mammography, extent of DCIS in proximity to margin, which margin is close [i.e., anterior excised to skin or posterior excised to pectoral fascia v margins associated with residual breast tissue]), cosmetic impact of re-excision, and overall life expectancy

14. Guideline recommendations
Excision without WBRT associated with higher rates of IBTR (26.0% vs 12.0%, P < )
Inconclusive evidence to suggest lower rate with wider margin than 2mm
Van Zee et al (2015):
16% for >10 mm,
23% for between 2.1 and 10 mm
27% for > 0-2 mm
41% for positive margins
Other studies: no significant difference
Van Zee et al: 16%for margins >10 mm, and increased to 23% for margins between 2.1 and 10 mm, 27% for > 0-2 mm, and 41% for positive margins
Other studies (ECOG): no significant difference

15. Guideline recommendations
Endocrine therapy reduced rate of IBTR in patient with positive margin (17.4% vs 11.5%)
No evidence to suggest association with margin width
Insufficient data to address association of margin width with
Patient factors
Radiation delivery
DCIS with microinvasion

16. Conclusion
Current evidence support adequate margin of 2mm for DCIS undergone BCT with WBRT
Selective re-excision for margins <2mm