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. Author manuscript; available in PMC: 2024 Sep 1.

Published in final edited form as: Abdom Radiol (NY). 2023 Apr 26;48(9):2836–2873. doi: 10.1007/s00261-023-03900-6

FIGURE 12: — Incomplete response (iCR) 7 months after treatment in a 73-year-old man with T3N+ rectal cancer 4 cm from the anal verge. (a) 5-mm straight axial MRI slice through the tumor bed reveals a T2-intermediate-signal circumferential tumor (arrow). (b) 5-mm straight axial b800 DWI slice shows associated tumor bed restriction (arrow) and nodes (arrowhead). (c) 5-mm straight axial T2WI slice shows tissue with decreased but obvious intermediate T2 signal still present circumferentially (arrow). (d) Matching b800 DWI shows abundant DWI restriction circumferentially (arrow). The patient declined surgery and developed liver and lung metastases. He also had a perforated synchronous sigmoid tumor.

TEACHING POINT: There is a classification schema that is being developed to grade response at first post-total neoadjuvant treatment (TNT) “decision point” MRI/endoscopy as:

Clinical complete response (cCR) – safe to continue to follow the Watch-and-Wait (W&W) approach

Near clinical complete response (nCR) –The effects of radiation continue to shrink the tumor towards becoming a scar, with diminishing T2 tumor/scar volume and diminishing DWI restriction compared with prior T2WI and DWI (along with endoscopic definitions), such that there is very little tumor and almost complete response; the patient may or may not continue on W&W at the discretion of the surgeon depending on how long out from TNT the MRI was performed.

Incomplete response (iCR) – This is a moniker only valid within 6 months of TNT wherein there is response but which is only moderate to good and less then nCR; such a patient is likely to go on to surgery but under extenuating circumstances could be allowed a trial of more W&W management, e.g., poor operative risk, refusal to undergo surgery, unconventional imaging time, or TNT schedule. In most instances, this type of response is allowed once and it is generally not safe to undergo W&W management.

FIGURE 12: — Incomplete response (iCR) 7 months after treatment in a 73-year-old man with T3N+ rectal cancer 4 cm from the anal verge. (a) 5-mm straight axial MRI slice through the tumor bed reveals a T2-intermediate-signal circumferential tumor (arrow). (b) 5-mm straight axial b800 DWI slice shows associated tumor bed restriction (arrow) and nodes (arrowhead). (c) 5-mm straight axial T2WI slice shows tissue with decreased but obvious intermediate T2 signal still present circumferentially (arrow). (d) Matching b800 DWI shows abundant DWI restriction circumferentially (arrow). The patient declined surgery and developed liver and lung metastases. He also had a perforated synchronous sigmoid tumor.

TEACHING POINT: There is a classification schema that is being developed to grade response at first post-total neoadjuvant treatment (TNT) “decision point” MRI/endoscopy as:

Clinical complete response (cCR) – safe to continue to follow the Watch-and-Wait (W&W) approach

Near clinical complete response (nCR) –The effects of radiation continue to shrink the tumor towards becoming a scar, with diminishing T2 tumor/scar volume and diminishing DWI restriction compared with prior T2WI and DWI (along with endoscopic definitions), such that there is very little tumor and almost complete response; the patient may or may not continue on W&W at the discretion of the surgeon depending on how long out from TNT the MRI was performed.

Incomplete response (iCR) – This is a moniker only valid within 6 months of TNT wherein there is response but which is only moderate to good and less then nCR; such a patient is likely to go on to surgery but under extenuating circumstances could be allowed a trial of more W&W management, e.g., poor operative risk, refusal to undergo surgery, unconventional imaging time, or TNT schedule. In most instances, this type of response is allowed once and it is generally not safe to undergo W&W management.