Spontaneous regression of colorectal cancer metastatic to retroperitoneal lymph nodes.

Spontaneous remissions have been reported in solid tumors such as melanoma and renal cell cancer. However, spontaneous remissions in colon cancer have not been previously radiographically confirmed. A case of colon cancer metastatic to the retroperitoneal lymph nodes that exhibited a durable spontaneous regression is reported. The exact trigger of this phenomenon has not been elucidated; however, an antitumor immune response is the most likely explanation. The identification and characterization of similar cases would probably result in defining a patient population that can be followed by observation and may result in the development of novel therapeutic strategies.