Table 3

Chemotherapy response score: summary of criteria

CRS1: No or minimal tumour responseMainly viable tumour with no or minimal regression-associated fibroinflammatory changes* limited to a few foci. Note: cases in which it is difficult to decide between regression and tumour-associated desmoplasia or inflammatory cell infiltration
CRS2: Partial tumour responseAppreciable tumour response amidst viable tumour, both readily identifiable and tumour regularly distributed. Note: cases ranging from multifocal or diffuse regression-associated fibroinflammatory changes*, with viable tumour in sheets, streaks or nodules, to extensive regression associated fibroinflammatory changes* with multifocal residual tumour which is easily identifiable
CRS3: Total or near-total tumour responseNo residual tumour OR minimal irregularly scattered tumour foci seen as individual cells, cell groups or nodules up to 2 mm in maximum size. Note: cases showing mainly regression-associated fibroinflammatory changes* or, in rare cases, no/very little residual tumour in complete absence of any inflammatory response; advisable to record whether ‘no residual tumour’ or ‘microscopic residual tumour present’
  • *Regression-associated fibroinflammatory changes: fibrosis associated with macrophages, including foam cells, mixed inflammatory cells and psammoma bodies; to distinguish from tumour-related inflammation or desmoplasia.

  • CRS, chemotherapy response score.