Definition of lines of treatment in metastatic colorectal cancer: a Delphi consensus

TL;DR

Experts in Spain reached a consensus on how to classify treatment lines for metastatic colorectal cancer, highlighting the need for standardized definitions to improve clinical decision-making.

Contribution

The study provides a Delphi consensus on the classification of treatment lines in metastatic colorectal cancer among Spanish oncology experts.

Findings

Consensus was achieved on 32 of 41 statements regarding treatment lines in metastatic colorectal cancer.

Experts agreed that maintenance therapy is part of first-line treatment and that switching biologics constitutes a new line.

Variability was observed in the use of biologics in perioperative settings and progression criteria.

Abstract

Metastatic colorectal cancer (mCRC) presents significant therapeutic challenges, with variability in the definition and classification of lines of treatment (LoTs). This study aimed to achieve consensus among Spanish oncology experts on the classification of LoTs through the application of the Delphi methodology.

A nationwide Delphi study was conducted in three phases. Twelve experts designed a two-round online survey that consisted of 41 statements across 11 sections. Statements were evaluated with a five-point Likert scale, with ≥ 70% agreement or disagreement as the criterion of consensus.

A total of 110 and 92 oncologists participated in the first and second rounds, respectively, with consensus achieved on 32 of 41 statements. Key agreements included definition of treatment lines before systemic therapy (98.18%), classification of relapses after six months of adjuvant therapy as first line (92.73%), and the inclusion of maintenance therapy as part of first-line treatment (98.18%). Variability arose on the use of biologics in perioperative settings (67.39% disagreement) and progression criteria, and 75% of experts agreed that a switch in biologics constitutes a new line. Thus, it is needed to standardize definitions in clinical practice.

This study highlights significant variability in the definition of LoTs for mCRC, which reflects the evolution of therapeutic landscape. The divergence between clinical trial criteria and real-world practices underscores the need for standardized definitions to enhance consistency in clinical decision-making. Refinement of guidelines on biologic agents, rechallenge strategies, and therapy classification is critical to advance mCRC management and improve patient outcomes. This consensus serves as a foundation for future research and guideline development.

The online version contains supplementary material available at 10.1007/s12094-025-03986-y.

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