Clinical Aspect: Chemo- and/or Radiation Therapy and Micrometastasis

Abstract

The significance of lymph node micrometastasis (LNM), including isolated tumor cells (ITCs), in gastrointestinal (GI) cancers has long been investigated and discussed. Due to advances in the development of diagnostic tools, the detection rate of LNM is increasing. However, the clinical significance of LNM in GI cancers remains controversial, much less than that for chemo- and/or radiation therapy and LNM. This chapter summarizes the present clinical aspects of chemo- and/or radiation therapy and LNM in GI cancers from a limited number of studies. Neoadjuvant therapy may reduce LNM in patients with esophageal cancer, and LNM has an equal negative impact on prognosis as in node-positive patients. In gastric cancer, chemotherapy has a marked effect on LNM in regional lymph nodes independent of whether the effects of chemotherapy are active against the primary tumor. In patients with colorectal cancer (CRC), neoadjuvant radiotherapy (NART) or neoadjuvant chemoradiotherapy (NACRT) may reduce LNM, and LNM after neoadjuvant therapy had a negative impact on the prognosis of node-negative cases. These findings suggest that neoadjuvant therapy effectively reduces LNM; however, the significance of LNM after neoadjuvant therapy on the prognosis of patients with GI cancer currently remains unclear.