Pan-Tumour Pathologic Response Guidelines Standardise Neoadjuvant Assessment Across Cancers - ASCPO Post

As neoadjuvant therapy expands across tumor types, pathologic response after surgery is increasingly used as a predictor of long-term survival and as a key clinical trial endpoint. However, response scoring systems have historically varied by tumor type, creating inconsistency in reporting and limiting cross-trial comparisons.

A joint effort by the Society for Immunotherapy of Cancer (SITC) and the International Neoadjuvant Melanoma Consortium has now produced the first unified, pan-tumor framework for assessing pathologic response to neoadjuvant therapy. The updated consensus guidelines harmonize evaluation across cancer types by focusing on three core components: percentage of residual viable tumor, necrosis, and regression in both primary tumor and lymph nodes.

The guidelines also standardize tissue sampling. Tumors ≤3 cm should be submitted entirely for embedding; larger tumors require at least one full cross-section from the longest dimension, including the tumor–host interface when feasible.

A multi-institutional reproducibility study demonstrated strong interobserver agreement among trained pathologists across 12 tumor types, supporting reliability of the unified approach. Correlation coefficients exceeded 0.8 for all key measures.

This harmonised system simplifies reporting, enhances comparability across studies, and may facilitate future regulatory use of pathologic response endpoints. Ongoing efforts aim to refine tumor-specific response thresholds while maintaining the overarching standardized framework.