Table 2.

Summary of histopathological tumour regression grade scales available in the literature for rectal cancer after neo-adjuvant treatment

TRG scale	Mandard
	(Low no. - More regression)[43]
0
1	Complete regression - absence of residual cancer and fibrosis
2	Presence of rare residual cancer
3	An increase in the number of residual cancer cells, but predominantly fibrosis
4	Residual cancer outgrowing fibrosis
5	Absence of regressive changes
TRG scale	Modified Mandard (Ryan)
	(Low no. - More regression)[37]
0
1	TRG 1 and 2 of the Mandard scale
2	TRG 3 of the Mandard scale
3	TRG 4 and 5 of the Mandard scale
4
5
TRG scale	Werner and Hoffler
	(Low no. - More regression)[41]
0
1	0% viable tumour cells
2	< 10% viable tumour cells
3	10%-50% viable tumour cells
4	> 50% viable tumour cells
5	No regression
TRG scale	Dworak
	(Low no. - Less regression)[35]
0	No regression
1	Dominant tumour mass with obvious fibrosis and/or vasculopathy
2	Dominant fibrotic change with few
	tumour cells or groups(easy to find)
3	Very few tumour cells in fibrotic tissue with or without mucous substance
4	No tumour cells, only fibrotic mass (total regression or response)
5
TRG scale	Modified Dworak
	(Low no. - Less regression)[38]
0	No regression
1	Regression ≤ 25% of tumour mass (dominant tumour mass with obvious fibrosis and/or vasculopathy)
2	Regression > 25%-50% of tumour mass (dominantly fibrotic changes with few tumour cells of groups, easy to find)
3	Regression > 50% of tumour mass (very few tumour cells in fibrotic tissue with or without mucous substance)
4	Complete (total) regression (or response): no vital tumour cells
5
TRG scale	AJCC 7th Edition[48]
0	Complete-no viable cells present
1	Moderate-single cells/small groups of cancer cells
2	Minimal-residual cancer outgrown by fibrosis
3	Poor-minimal or no tumour kill, extensive residual cancer
4
5
TRG scale	Memorial Sloan-Kettering (Low no. - Less regression)[47]
0	0%-85% regression
1	86-99% regression
2	100% regression
3
4
5
TRG scale	Cologne
	(Low no. - Less regression)[40]
0
1	> 50 % Viable rectal tumour cells
2	10%-50% Viable rectal tumour cells
3	Near complete regression with < 10% Viable rectal tumour cells
4	Complete regression (pathologic complete remission and ypT0)
TRG scale	Bujko/Glynne Jones
	(Low no. - More regression)[18,44]
0	No cancer cells
1	A few cancer foci in less than 10% of tumour mass
2	Cancer seen in 10%-50% of tumour mass
3	Cancer cells seen in more than 50% of tumour mass
4
TRG scale	College of American Pathologists[50]
0	Complete response: No residual tumour
1	Marked response: Minimal residual cancer
2	Moderate response: Residual cancer outgrown by fibrosis
3	Poor or no response: Minimal or no tumour kill; extensive residual cancer
4
TRG scale	RCPath system
	(Low no. - More regression)[42]
0
1	No residual cells and/or mucus lakes only
2	Minimal residual tumour i.e., microscopic residual tumour foci only
3	No marked regression
4
TRG scale	RCRG system
	(Low no. - More regression)[34]
0
1	Sterilisation or only microscopic foci of adenocarcinoma with marked fibrosis
2	Marked fibrosis but macroscopic disease present
3	Little or no fibrosis with abundant macroscopic disease
4
TRG scale	Mod RCRG system
	(Low no. - More regression)[45]
0
1	Macroscopic features may be varied. Microscopy reveals no tumour or < 5% of area of abnormality
2	Macroscopic features may be varied. Microscopy reveals combination of viable tumour and fibrosis. Tumour comprises 5%-50% of overall area of abnormality
3	Macroscopic or microscopic features may not be significantly different. Over 50% comprises tumour. Some fibrosis may be present but no more than untreated cases
4
TRG scale	Japanese
	(Low no. - Less regression)[25]
0	No regression
1a	Minimal effect (necrosis less than 1/3)
1b	Mild effect (necrosis less than 2/3 but more than 1/3)
2	Moderate effect (necrosis more than 2/3 of the lesion)
3	No tumour cells
TRG scale	Ruo
	(Low no. - Less regression)[39]
0	No evidence of response
1	1% to 33% response
2	34% to 66% response
3a	67% to 95% response
3b	96% to 99% response
4	100% response (no viable tumour identified)
TRG scale	Junker and Muller
	(Low no. - Less regression)[46]
1	No regression
2a	> 10% residual tumour cells
2b	< 10% residual tumour cells
3	Total regression (no viable tumour cells)
TRG scale	Rodel
	(Low no. - Less regression)[36]
Poor	TRG 1 and 0 of the Dworak scale
Intermediate	TRG 2 and 3 of the Dworak scale
Complete	TRG 4 of the Dworak scale
TRG scale	Four point scale
	Swellengrebel et al[49]
pCR	Pathological complete response without residual primary tumour
Near pCR	Isolated residual tumour cells/small groups of residual tumour cells
Response	Stromal fibrosis outgrowing tumour
No response	No regression or those with stromal fibrosis outgrown by tumour
TRG scale	Modified Mandard TRGN by Dhadda et al[51]
TRGN 1	Complete regression with absence of residual cancer and fibrosis extending through the wall
TRGN 2	Presence of rare residual cancer cells scattered through the fibrosis
TRGN 3	An increased number of residual cancer cells, but fibrosis is still predominant