Extraintestinal Endosonography

Introduction

The use of endoscopic ultrasound (EUS) has grown over the last 30 years, and it is now a well-established diagnostic method for the assessment of a range of gastrointestinal (GI) disorders, including the evaluation and staging of many types of endoluminal cancers. This chapter discusses EUS applications relating to extraintestinal structures, organs, and lesions. The objectives of this chapter are to review the utility of EUS for evaluating the mediastinum in both benign and malignant disease processes, including the detection of mediastinal lymph node metastases in lung cancer. Mass lesions in the paragastric and retroperitoneal organs (excluding the bile duct, gallbladder, and pancreas) are reviewed, including detection of lesions of the adrenal gland, liver, and kidneys. Ascites and pleural fluid are examined along with unusual extraintestinal lesions.

Lung Cancer

Lung cancer is the leading cause of cancer death in the United States in men and women, and has an overall 5-year survival rate of 15%. Treatment decisions are based on the location and extent of the tumor. The presence of extrapulmonary metastasis is crucial because patients without mediastinal involvement are potential candidates for resection. The distinction between non–small-cell lung cancer (NSCLC), which accounts for 80% of tumors, and small-cell lung cancer (SCLC), which accounts for 20% of tumors, is important because of the more aggressive nature of SCLC. SCLC is usually classified as limited or extensive disease, although the criteria for these two categories remain controversial. Although the TNM (primary tumor, regional nodes, metastases) staging system traditionally has not been used in staging SCLC, studies have suggested using the 7th edition of the TNM classification scheme for clinical trials and registry information, to guide future management. The forthcoming 8th edition of the TNM classification system has proposed changes to the T classification scheme, highlighting tumor size as a key feature. Metastatic disease is detected in 80% of SCLC cases at the time of diagnosis and tends to spread quickly so that surgery is considered less often in SCLC compared with NSCLC. Although highly responsive to radiotherapy and chemotherapy, SCLC usually recurs within 2 years.

In comparison, half of NSCLC cases are localized or locally advanced and can be treated by surgery, the cornerstone of therapy for NSCLC, or with adjuvant therapy with or without resection. NSCLC, which includes adenocarcinoma, squamous cell cancer, and large-cell cancer, was previously staged using the 2002 International Staging System. Recently, NSCLC, has been staged using the 7th edition until December 31, 2017 ( Box 47.1 ) and subsequently will be staged using the future 8th edition. This section focuses on EUS applications in the diagnosis and staging of NSCLC, although much of what is covered can be applied to SCLC.