[Radiologic response assessment in metastatic colorectal cancers]

The increasing indications of cytostatic biotherapies and the improvement in metastatic surgery have profoundly changed the management of metastatic colorectal cancer (mCRC) patients. Then the development of prognostic and predictive scores would be useful to stratify the treatments. Tumor radiological measurement is crucial to estimate treatment efficacy, and to predict pathological response and survival, and this parameter is included when a prognostic score is developed. But the standard size-based radiologic criteria, the Response Evaluation Criteria in Solid Tumors (RECIST), was designed ten years ago to assess tumor volume reduction after cytotoxic chemotherapy only. Nowadays, this method may be insufficient for mCRC patients. The aim of this review is to describe the different radiological assessments evaluated in mCRC, and to underline their correlations with patient's survival and pathologic response. A better knowledge of these radiological measurements would help to better integrate them in prospective trials, and in the prognostic and predictive scores. The choice of radiological measurement could be discussed regarding patient's situation, combining different approaches, and assessing tumoral mass quantification.