Tumor deposits

Last revised by Henry Knipe on 1 Mar 2024

Tumor deposits in the context of colon and rectal cancer are discrete nodules of tumor tissue within the mesocolon or mesorectum respectively, found along the path of draining veins, and are distinct from lymph node metastases 1-3. They are found in >50% of MRI studies of patients with rectal cancer 1.

Tumor deposits can be seen on CT and MRI (mrTDs) and are discontinuous to the main primary tumor, along the path of draining vessels and are found to be interrupting the vessels when assessed on two orthogonal views 1-3. These vessels will frequently be found to have signs of extramural venous invasion. In contrast, lymph node metastases do not interrupt the course of vessels although may be adjacent 3. Tumor deposits have an irregular margin 3, as opposed to lymph node metastases which generally will have a smooth capsule.

Tumor deposits, alongside the ancillary finding of extramural venous invasion, are increasingly recognized as being the most important predictors of distant metastatic disease, overall survival and disease-free survival for patients with rectal cancer 1,2. It has been found that moving from a positive to a negative mrTD status as a result of chemoradiotherapy, had a better outcome than those who remain mrTD positive following such therapy 1.

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