. Incomplete response. Endoscopic and T2-weighted MRI images both pre- and post-treatment are shown for a patient who experienced no significant response to induction chemotherapy followed by CRT. This is a 45-year-old woman who underwent 8 cycles of induction FOLFOX followed by CRT with minimal or no response. The patient was therefore referred for TME
Guidelines for tumor measurement
For the endoscopic exam, the length of the tumor is defined as the difference between the distance of the proximal and distal margins in relation to the anal verge. For MRI/CT, the standard and DW-MRI sequences will be obtained in 1.5 T or 3 T units by using a phased-array body coil. All imaging studies will be interpreted by expert radiology staff at the patient’s primary treatment center to determine patient eligibility, clinical staging, and tumor response, according to standard clinical criteria.
Criteria for response after neoadjuvant therapy
The primary tumor and the regional lymph nodes will be evaluated and measured by endoscopic exam and rectal MRI during re-staging. Central imaging review will be performed by the Radiology PI at MSKCC after receipt of baseline and post-TNT images. For quality control purposes, baseline MRI images will be collected for the first two patients enrolled at each site. MRI images taken at interval evaluation are required for all MSKCC patients, and are recommended for participating sites. These interval evaluation images will be submitted on disc for central review. All submitted discs will be de-identified, labeled using the unique study number, and in the DICOM format. MRI images taken at re-staging will be collected for all patients, and sent to MSKCC on disc for central review. Local and central interpretation will be tracked. Discrepancies between clinical examination and imaging will be resolved by the local investigator, but will be communicated to the PI and Radiology PI at MSKCC. In the event that the radiologist at MSKCC disagrees with a site assessment, these discrepancies will be relayed to local the PI and radiologist. No response will be relayed to the participating site if, upon review of submitted images, there are no discrepancies in assessment. In general, clinical examination will prevail over imaging in assessment of local tumor response. Our regression schema, an online resource we have created for all investigators, and the tabulated form will be used to enhance uniformity of evaluation and provide quantitative endpoints which we can use to provide a more precise, consistent means of evaluating assessment at the end of the study. Details of this three-tiered response regression schema can be found below (Table 2, and see below).
One of the main challenges to implementation of a NOM protocol at a multi-institutional level is the development of uniform and reproducible criteria for tumor response. To that end, our consortium organized a multidisciplinary videoconference on aimed at developing a consensus on the clinical criteria of tumor response. The participants-colorectal surgeons, medical oncologists, radiation oncologists, pathologists and radiologists-elaborated a three-tiered IWantBlacks assessment of response/regression schema to differentiate between patients with a cCR who are therefore candidates for NOM, from those without a cCR who are candidates for TME. This regression schema was further discussed at the American Society of Colon and Rectal Surgeons Annual Scientific Meeting in Hollywood, Florida in erican College of Surgeons Clinical Congress in . The regression schema is presented in Table 2, and will be available online by requesting access via Dr. Smith (). The regression schema is based on relatively subjective endoscopic and radiological criteria and has not been validated yet; however, it may provide some degree of uniformity that may help to maintain consistency and reduce variability between institutions.