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Relevance of shrinkage versus fragmented response patterns in rectal cancer.

Authors :
Kus Ozturk S
Graham Martinez C
Sheahan K
Winter DC
Aherne S
Ryan ÉJ
van de Velde CJ
Marijnen CA
Hospers GA
Roodvoets AG
Doukas M
Mens D
Verhoef C
van der Post RS
Nagtegaal ID
Source :
Histopathology [Histopathology] 2023 Dec; Vol. 83 (6), pp. 870-879. Date of Electronic Publication: 2023 Aug 23.
Publication Year :
2023

Abstract

Aims: Partial response to neoadjuvant chemoradiotherapy (CRT) presents with one of two main response patterns: shrinkage or fragmentation. This study investigated the relevance of these response patterns in rectal cancer, correlation with other response indicators, and outcome.<br />Methods and Results: The study included a test (n = 197) and a validation cohort (n = 218) of post-CRT patients with rectal adenocarcinoma not otherwise specified and a partial response. Response patterns were scored by two independent observers using a previously developed three-step flowchart. Tumour regression grading (TRG) was established according to both the College of American Pathologists (CAP) and Dworak classifications. In both cohorts, the predominant response pattern was fragmentation (70% and 74%), and the scoring interobserver agreement was excellent (k = 0.85). Patients with a fragmented pattern presented with significantly higher pathological stage (ypTNM II-IV, 78% versus 35%; P < 0.001), less tumour regression with Dworak (P = 0.004), and CAP TRG (P = 0.005) compared to patients with a shrinkage pattern. As a predictor of prognosis, the shrinkage pattern outperformed the TRG classification and stratified patients better in overall (fragmented pattern, hazard ratio [HR] 2.04, 95% confidence interval [CI] 1.19-3.50, P = 0.008) and disease-free survival (DFS; fragmented pattern, HR 2.50, 95% CI 1.23-5.10, P = 0.011) in the combined cohorts. The multivariable regression analyses revealed pathological stage as the only independent predictor of DFS.<br />Conclusions: The heterogeneous nature of tumour response following CRT is reflected in fragmentation and shrinkage. In rectal cancer there is a predominance of the fragmented pattern, which is associated with advanced stage and less tumour regression. While not independently associated with survival, these reproducible patterns give insights into the biology of tumour response.<br /> (© 2023 The Authors. Histopathology published by John Wiley & Sons Ltd.)

Details

Language :
English
ISSN :
1365-2559
Volume :
83
Issue :
6
Database :
MEDLINE
Journal :
Histopathology
Publication Type :
Academic Journal
Accession number :
37609761
Full Text :
https://doi.org/10.1111/his.15027