Imaging assessment of tumor response: past, present and future
1Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
Abstract:
Anatomical response assessment criteria have been in use for decades, with the WHO guidelines being replaced by Response Evaluation Criteria in Solid Tumors (RECIST), updated in 2009 to RECIST 1.1. These methods rely on a change in size of a tumor as the main response criteria, but newer cytostatic agents tend to target tumor function at a molecular level before changing the size of a lesion. Recent modifications, such as the Choi criteria, have improved assessment by taking into account density of tumor, but all of these criteria fail to utilize functional imaging parameters, which are becoming increasingly available, including perfusion CT, perfusion MRI, diffusion-weighted imaging, magnetic resonance spectroscopy, dynamic contrast-enhanced ultrasound and combined PET/computed tomography. Developments in these modalities and standardization of imaging acquisition will help to optimize the next set of response criteria, with inclusion of multiparametric, functional modalities, evaluating tumors at the same molecular level at which they are being targeted by therapeutic agents.
Insights
Current tumor response criteria, like RECIST 1.1, focus on size. Newer cancer therapies target molecular function, necessitating advanced imaging techniques for accurate assessment of treatment effectiveness.
Area of Science:
- Oncology
- Radiology
- Medical Imaging
Background:
- Anatomical response assessment criteria, such as Response Evaluation Criteria in Solid Tumors (RECIST 1.1), have historically relied on tumor size changes.
- Emerging cytostatic agents increasingly target tumor function at a molecular level, preceding significant changes in lesion size.
Purpose of the Study:
- To highlight the limitations of current anatomical tumor response criteria in evaluating novel molecularly targeted therapies.
- To advocate for the integration of functional imaging parameters into future response assessment criteria.
Main Methods:
- Review of existing anatomical response criteria (WHO, RECIST 1.1, Choi criteria).
- Identification of limitations in assessing therapies targeting tumor function.
- Exploration of advanced functional imaging modalities (perfusion CT/MRI, DWI, MRS, DCE-US, PET/CT).
Main Results:
- Current criteria based on size (e.g., RECIST 1.1) are insufficient for evaluating treatments targeting molecular pathways.
- Functional imaging parameters offer a more sensitive measure of tumor response to molecularly targeted agents.
- Existing criteria like Choi criteria incorporate density but still lack functional assessment.
Conclusions:
- Future tumor response criteria must incorporate multiparametric, functional imaging modalities.
- Standardization of advanced imaging acquisition is crucial for optimizing next-generation response assessment.
- Aligning response evaluation with the molecular targets of novel therapies is essential for accurate treatment assessment.
