A Worldwide Survey on Pathological Measurement of Residual Breast Cancer After Neoadjuvant Therapy: Different Interpretations of the ypTNM Classification

Kwakkenbos, K; Van Bockstal, MR; Shaaban, AM; Brogi, E; Cserni, G; Ellis, IO; Foschini, MP; Fox, SB; Bago-Horvath, Z; Jaffer, S; Jager, A; Pinder, SE; Provenzano, E; Quinn, CM; Rakha, EA; Raymond, WA; Tan, PH; Tse, GM; Varga, Z; Wen, HY; van Deurzen, CHM

Author(s): Kwakkenbos, K; Van Bockstal, MR; Shaaban, AM; Brogi, E; Cserni, G; Ellis, IO; Foschini, MP; Fox, SB; Bago-Horvath, Z; Jaffer, S; Jager, A; Pinder, SE; Provenzano, E; Quinn, CM; Rakha, EA; Raymond, WA; Tan, PH; Tse, GM; Varga, Z; Wen, HY; van Deurzen, CHM;
Details: Publication Year 2026-03,Volume 39,Issue #3,Page 100963
Journal Title: Modern Pathology
Publication Type: Research article
Abstract: The extent of residual disease after neoadjuvant chemotherapy (NAC) in patients with breast cancer (BC) holds prognostic value. However, current practices for reporting post-NAC BC specimens according to the ypTNM classification vary. This study aimed to map these practices and provide recommendations for standardization. A survey was developed and globally circulated to pathologists with a special interest in BC through personal networks and working group mailing lists. The survey included general questions about tumor diameter assessment, as well as graphical scenarios presenting different distributions of tumor cells. We did not provide definitions mentioned in reporting guidelines to capture unbiased current real-world practices. A total of 208 pathologists from 35 countries completed the survey. Almost all responding pathologists (97.1%) reported the ypTNM in daily practice. Despite self-reported strict adherence to the eighth edition of the international ypTNM classification, we found substantial variation in practice concerning the application of this staging system, particularly in cases with an uneven distribution of scattered residual disease. Notably, 57.2% of respondents reported measuring the largest "continuous cluster of tumor cells," but the interpretation of this definition varied widely. This international survey identifies the challenges and practice heterogeneity in the current application of the ypTNM staging system, which hampers the value of ypTNM reporting in daily practice. To enhance reproducibility and to provide more reliable post-NAC risk stratification, we recommend adopting standardized reporting with clearer pattern-based definitions of the ypTNM guidelines, supplemented with the elements of the residual cancer burden system.
Publisher: Elsevier
Keywords: Humans; Neoadjuvant Therapy; *Breast Neoplasms/pathology/drug therapy/classification/therapy; Female; *Neoplasm, Residual/pathology; *Neoplasm Staging/methods; Surveys and Questionnaires; *Practice Patterns, Physicians'; breast cancer; neoadjuvant chemotherapy; pTNM classification; pathology; residual cancer burden; residual disease
Department(s): Pathology
Publisher's Version: https://doi.org/10.1016/j.modpat.2026.100963
Open Access at Publisher's Site: https://doi.org/10.1016/j.modpat.2026.100963
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 2026-01-29 05:40:53

Last Modified: 2026-04-14 03:18:18