Nonoperative management of gastrointestinal malignancies in era of neoadjuvant treatment

Cancers derived from the gastrointestinal (GI) tract are often treated with radical surgery to achieve a cure. However, recent advances in the management of GI cancers involve the use of a combination of neoadjuvant radiation and chemotherapy followed by surgical intervention to achieve improved local control and cure. Interestingly, a small proportion of patients with highly sensitive tumors achieved a pathological complete response (pCR) (no residual tumor cells in the resected specimen) to neoadjuvant chemoradiation therapy (nCRT). The desire for organ preservation and avoidance of surgical morbidity brings the idea of a nonoperative management (NOM) strategy. Because of the different nature of tumor biology, GI cancers present diverse responses to nCRT, ranging from high sensitivity (anal cancer) to low sensitivity (gastric/esophageal cancer). There is an increasing attention to NOM of localized GI cancers; however, without the use of biomarkers/imaging parameters to select such patients, NOM will remain a challenge. Therefore, this review intends to summarize some of the recent updates from the aspect of current nCRT regimens, criteria for patient selection and active surveillance schedules. We also hope to review significant sequelae of radical surgery and the complications of nCRT to clarify the directions for optimization of nCRT and NOM for oncologic outcomes and quality of life.