Endoscopic Diagnosis and Treatment for Colorectal Cancer

Abstract

Colonoscopy plays an important role in the medical care of patients with colorectal cancer. It is generally used for both the diagnosis of different stages of colorectal cancer and the treatment of early colorectal cancer and its precursors. The recent progress in colonoscopy has been remarkable. Endoscopes with variable rigidity and small diameters provide efficient insertion to the cecum and result in lower distress for patients. Trained colonoscopists can insert endoscopes into the cecum within a few minutes, and it is not necessary to anesthetize patients without severe peritoneal adhesion. We can obtain good-quality pictures and special images to assist in diagnosis by using highvision endoscopes, magnifying endoscopes, dye spray, and narrow-band imaging (NBI). Determining whether a colorectal carcinoma can be curatively resected by endoscopic treatment or whether the carcinoma has a risk of lymph node metastasis is a very delicate and important task. In particular, the depth of cancer invasion is related to lymph node metastasis; therefore, endoscopic ultrasonography and the classification of pit patterns, capillary patterns via NBI, and the lesion-lifted condition are used to diagnose the depth of cancer invasion (Kato, 2001, Sano, 2008). Treatment for colorectal neoplastic lesions begins with hot biopsy and snare polypectomy, and recently, endoscopic submucosal resection (EMR), piecemeal EMR (EPMR), and endoscopic submucosal dissection (ESD) have become available for large and flat lesions of the colon and rectum. Early colorectal carcinoma is defined as a carcinoma within the submucosal layer that is not invading the muscularis propria. Carcinoma in situ (mucosal carcinoma) and carcinoma that slightly invades the submucosa and without risk factors for metastasis do not metastasize into lymph nodes or distant organs. Nonmetastatic carcinoma is cured by local resection with colonoscope. It is important to make an accurate diagnosis by endoscopy and to perform confident resection for pathological evaluation. In this chapter, we describe endoscopic diagnosis for colorectal carcinoma and differential diagnosis, and treatment options for early colorectal cancer without metastasis and for adenoma which is regarded as a precancerous condition. In addition, we briefly discuss risk factors for lymph node metastasis in early colorectal carcinoma.