Author of 1 Presentation
SS 2.6 - The impact of mismatch repair status on the preoperative staging of local colon cancer
Abstract
Purpose
CT scan is standard in preoperative local staging of colon cancer. Tumours with a deficient mismatch repair (dMMR) system are characterised by unique clinical and pathophysiologic aspects that may impact the accuracy of the preoperative CT staging.
Material and methods
Data from the Danish Colorectal Cancer Group national clinical database addressing a cohort of patients operated for stage I-III colon cancer during 2010-15 were analysed. The analyses of MMR status had been conducted consecutively through means of immunohistochemistry. All CT scans were blindly assessed by a certified radiologist.
Results
Data from 590 patients, operated at a specialised cancer centre, were available for analyses. 135 (22.9%) of the patients had tumours demonstrating dMMR. The overall correlation of the clinical and pathological T-category was significant for both groups. There was an inferior correlation between clinical (cN) and pathological (pN) N-category (p>0.05) in pMMR cancers with a higher degree of over-staging assessed by CT scan compared to a significant correlation between cN and pN stages in pMMR cancers (p<0.01). Of the 91 dMMR tumours assessed node-positive by the preoperative CT scan, 59 (64.8%) showed no sign of metastatic involvement at the postoperative assessment.
Conclusion
Preoperative CT staging of dMMR colon cancer seems to overestimate nodal involvement and two-thirds of the patients preoperatively judged node-positive are false positive. The overall clinical value of a routine assessment of MMR status in the diagnostic setup is evident and the current study argues for implications to treatment decisions as well.
Video-on-demand
Author of 1 Presentation
SS 2.6 - The impact of mismatch repair status on the preoperative staging of local colon cancer (ID 506)
Abstract
Purpose
CT scan is standard in preoperative local staging of colon cancer. Tumours with a deficient mismatch repair (dMMR) system are characterised by unique clinical and pathophysiologic aspects that may impact the accuracy of the preoperative CT staging.
Material and methods
Data from the Danish Colorectal Cancer Group national clinical database addressing a cohort of patients operated for stage I-III colon cancer during 2010-15 were analysed. The analyses of MMR status had been conducted consecutively through means of immunohistochemistry. All CT scans were blindly assessed by a certified radiologist.
Results
Data from 590 patients, operated at a specialised cancer centre, were available for analyses. 135 (22.9%) of the patients had tumours demonstrating dMMR. The overall correlation of the clinical and pathological T-category was significant for both groups. There was an inferior correlation between clinical (cN) and pathological (pN) N-category (p>0.05) in pMMR cancers with a higher degree of over-staging assessed by CT scan compared to a significant correlation between cN and pN stages in pMMR cancers (p<0.01). Of the 91 dMMR tumours assessed node-positive by the preoperative CT scan, 59 (64.8%) showed no sign of metastatic involvement at the postoperative assessment.
Conclusion
Preoperative CT staging of dMMR colon cancer seems to overestimate nodal involvement and two-thirds of the patients preoperatively judged node-positive are false positive. The overall clinical value of a routine assessment of MMR status in the diagnostic setup is evident and the current study argues for implications to treatment decisions as well.