Modified Mandard Tumour Regression Grade Predicts Residual Cancer Burden Score in Neoadjuvant Treated Breast Cancer
Ciara Ryan, Jessica White, Fionnuala O'Connell, Tara Jane Browne, Linda Feeley, Michael W Bennett. Cork University Hospital, Cork, NA, Ireland
Background: Evaluation of pathologic response to neoadjuvant treatment in breast cancer is an important prognostic factor, however, criteria for its classification have not been standardized. The Residual Cancer Burden (RCB) system is frequently used and combines several histologic parameters, including nodal status, into a complex logarithmic equation (RCB=1.4(finvdprim)0.17+[4(1-0.75)LN)dmet]0.17) yielding four categories - pathologic complete response (pCR) and RCB scores 1-3 - which correlate with distant relapse-free survival (0-36% at 5 yrs). The Mandard Tumour Regression Grade (TRG) is a simple, easily applied qualitative comparison of relative proportion of tumour bed residual carcinoma and fibrosis. It is frequently applied in gastrointestinal cancers, but its use has not been studied in breast cancer.
Design: We aim to
1) Compare Mandard TRG to RCB
2) Modify Mandard TRG to incorporate nodal status
3) Compare modified system to validated RCB score in the same cohort
Fifty consecutive neoadjuvant-treated breast cancer cases (2011-12) were classified using the Mandard TRG. This system was then modified to incorporate nodal status. The same cases were also classified into RCB categories using the online calculator. Two pathologists classified each case.
Results: Mandard TRGs and RCB classes are compared in Table 1.
|1 - Complete regression||10||1*||0||0|
|2 - Isolated cell nests||0||3||8*||2*|
|3 - More residual cancer but fibrosis > tumour||0||0||1||6*|
|4 - Residual cancer > fibrosis||0||0||1||6*|
|5 - No regression||0||0||0||1|
|Recurrence Risk||RCB Class||Mandard TRG+/- LN||MODIFIED Mandard TRG|
|RCB 1||1 + LN||2|
|Significant (22-36%)||RCB 2||2 + LN||3|
|RCB 3||2 + LN (>10)||3|
|3 + LN||4|
|4 + LN||5|
|5 + LN||5|