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Table 1 Classification systems of pathological response to neoadjuvant breast cancer treatment

From: Neoadjuvant trials in early breast cancer: pathological response at surgery and correlation to longer term outcomes – what does it all mean?

Classification system Comment
American Joint Committee on Cancer/Union for International Cancer Control staging system 7th edition
ypT ypN, same categories as for adjuvant setting No evaluation of response;
No published data relating current edition definitions to survival outcomes
Chevallier
Class 1. No invasive carcinoma or DCIS, negative lymph nodes Class 1 and 2 = pCR (DCIS allowed)
Class 2. DCIS in the breast, no invasive carcinoma, negative lymph nodes
Class 3. Invasive carcinoma with stromal alteration
Class 4. Few modifications of tumour appearance
Sataloff
Tumour: T-A includes pCR and minimal residual disease
 T-A. Total or near total therapeutic effect T-A versus other categories associated with survival outcomes
 T-B. >50 % therapeutic effect, but less than T-A
 T-C. <50 % therapeutic effect
 T-D. No therapeutic effect
Nodes:
 N-A. Evidence of therapeutic effect, no metastasis
 N-B. No nodal metastasis or therapeutic effect
 N-C. Evidence of therapeutic effect, but metastasis present
 N-D. Metastatic disease, no therapeutic effect
Miller Payne
Grade 1. No reduction in overall cellularity DCIS allowed for pCR
Grade 2. Minor loss of tumour cells (up to 30 %) Does not include response in the lymph nodes
Grade 3. 30–90 % reduction in tumour cellularity Association with survival outcomes
Grade 4. >90 % loss of tumour cellularity  
Grade 5. No malignant cells identifiable; DCIS may be present
Pinder
Breast: DCIS allowed for pCR
 1. pCR: (1) no residual carcinoma or (2) no residual invasive tumour but DCIS present.  
 2. Partial response: (1) minimal residual disease ( <10 % of tumour remaining) , (2) evidence of response with 10–50 % of tumour remaining or (3) >50 % of tumour cellularity remaining with some features of response present.
 3. No evidence of response to therapy.
Lymph nodes: Practical approach which is easy to apply
 1. No evidence of metastasis or response. No published data regarding association with survival outcomes
 2. Metastases not present but evidence of response.
 3. Metastasis present with evidence of response.
 4. Metastasis present with no evidence of response.
Residual Cancer Burden score
Combines tumour size in two dimensions, average residual cellularity, number of involved nodes and size of largest metastases. Online calculator to generate a continuous numerical index that is subdivided into four classes (0 = pCR, I, II and III). Quantifies residual disease rather than evaluates response
Reproducible and relatively easy to apply
Validated in several independent cohorts
Significant association with survival outcomes over long term follow up
  1. DCIS ducal carcinoma in situ, pCR complete pathological response