Imaging response assessment in oncology

Abstract

The role of imaging in the clinical setting as well as in the drug development process is expanding rapidly. Imaging technology now exists that is capable of detecting tumor response within hours. In parallel with this advance, a new array of more targeted and specific therapies are being developed. This paradigm shift in turn demands a more sophisticated way of quantifying response. There is a need to update and modify the current response evaluation criteria in solid tumors (RECIST), which rely solely on anatomic size measurement of tumors. In addition, response assessment guidelines will need to be increasingly disease-specific. Response assessment by imaging is now intimately involved with all stages of the drug development process, from exploratory drug discovery through clinical trials, as well as in clinical use. Imaging biomarkers and surrogate endpoints have the potential to speed drug approval significantly. The major funding institutions and the pharmaceutical industry are working more and more with researchers to help maintain progress in this multidisciplinary area involving oncologists, radiologists, molecular imaging specialists, medical physicists, and computer scientists.

High-Grade Soft-Tissue Sarcomas: Tumor Response Assessment—Pilot Study to Assess the Correlation between Radiologic and Pathologic Response by Using RECIST and Choi Criteria

“…In a proportion of patients, there is no decrease in tumor size, despite the appearance of hypoattenuation within the lesions at computed tomography (CT). So, new criteria have been recently proposed for GISTs and incorporate tumor attenuation in addition to tumor size (11). These criteria have been demonstrated to correlate with patient outcomes better than RECIST criteria.…”

“…It has always been difficult to demonstrate partial response to therapy at imaging in many advanced solid tumors (10)(11)(12)(13)(14)(15). Molecular-targeted therapies give rise to a different antitumor effect and highlight the limitations of size criteria in the assessment of tumor response to these agents.…”

“…There has always been debate about these criteria, because it often has been difficult to correlate response and survival in advanced solid tumors. The introduction of the newest moleculartargeted therapies has fostered further discussion (6)(7)(8)(9)(10)(11)(12)(13)(14)(15). For example, patterns of tumor response of gastrointestinal stromal tumors (GISTs) being treated with imatinib are peculiar (16)(17)(18)(19)(20)(21)(22).…”

Tumor response assessment by modified Choi criteria in localized high‐risk soft tissue sarcoma treated with chemotherapy

“…However, the introduction of molecular-targeted therapies has emphasized the limitations of RECIST in terms of their validity, because tumor response may be nondimensional, especially in an early phase. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] In these patients, tumor response is marked by changes in the tumor radiologic aspect and in its functional imaging.…”

Évolution des critères d’évaluation de la réponse tumorale: apport de l’imagerie fonctionnelle

“…Le National Cancer Institute (NCI) a é dicté des rè gles concernant la pré paration des patients et l'acquisition des images pour tout essai incluant le TEP-scan [15]. L'espoir est que la technique, parmi d'autres imageries fonctionnelles é mergentes, donnera des informations trè s pré coces sur la ré ponse tumorale, dè s la premiè re cure et permettra de comprendre pourquoi certains patients ré pondent et d'autres non [8]. Avec le TEP-scan, comme pour l'IRM, s'ouvrent d'autres potentialité s, en particulier l'imagerie directe de l'angiogenè se en utilisant des radiotraceurs (technetium-99m, iodine-124, samarium-153) lié s à des anticorps dirigé s contre des facteurs de croissance intervenant dans le processus d'angiogenè se ou leurs ré cepteurs, comme les thymidinekinases [6,22].…”