The rediscovery of endoscopic ultrasound (EUS) in gastric cancer staging.

Although its incidence varies greatly between Eastern and Western countries, gastric carcinoma still represents the second leading cause of cancer deaths worldwide. Despite modern surgical techniques allow for high curative resection rates, long-term survival curves are still very disappointing. For this reason, neoadjuvant radiochemotherapy regimens are being increasingly adopted in attempt to improve the survival of patients with advanced gastric cancer. In order to identify which patients should be allocated to preoperative treatments, it is crucial to rely on accurate staging techniques. Soon after the first descriptions of the gastric wall 5-layer structure, - endoscopic ultrasound (EUS) became a natural candidate technique for the staging of gastric cancer. The first reports in this field demonstrated good results in terms of sensitivity and specificity both for T and N staging. - Since then, gastric cancer has traditionally been a major area of research in EUS, mainly in regard to differentiating tumor depth and detecting regional lymph node metastases, with more than 130 studies published in the period 1980-2010. In more recent years, the impact of EUS on patients’ management has also been evaluated in high-level of evidence publications such as meta-analyses and systematic reviews. - Until a few years ago, the impact of EUS in gastric cancer was limited by the lack of therapeutic options, surgery being the only opportunity either with curative or with palliative intent. The clinical arena of gastric cancer has changed substantially in recent years when treatments became more numerous. Besides the traditional surgical approach, endoscopic mucosal resection and submucosal dissection were adopted for the early stages of the disease (T1 N0) and neoadjuvant therapies (preoperative and perioperative) were introduced for the advanced stages (T3/T4 and N+). As a consequence, the potential role of EUS in gastric cancer has become much more attractive to identify the patients amenable to minimally invasive treatment, those who should undergo primary surgery, and those who need a neoadjuvant therapy. In this respect, the most recent guidelines of the National Comprehensive Cancer Network, an international highly reputed authority, have introduced EUS as a preferred modality of gastric cancer staging if no evidence of M1 disease is present at computed tomography-positron emission tomography. In this issue of the Journal, Kutup et al. reported a large single center retrospective study assessing the potential influence of EUS on decision making in gastric cancer without distant metastases. The authors’ assumption was that chemotherapy would be applied only in locally advanced cancers (T3/4 or any N+), whereas primary surgery would be performed with T1/2 N0 tumors. They analyzed the endosonographic and histopathological staging of 123 patients treated by primary surgery between 1993 and 2008. During the long study period, EUS was performed by 6 different expert endosonographers, using a radial echoendoscope at 7.5, 10 and 12 MHz. Overall T staging was correct in 45% of the patients and overall N staging was correct in 72%. Regarding the ability to differentiate between early and advanced stages of gastric cancer by EUS, distinction between T1/2 and T3/4 tumors was made with 50% sensitivity (correct recognition of T1/2) and 81% specificity (correct recognition of T3/4). According to N staging (uN0 vs. uN+), 41% of the tumors were understaged (being wrongly assigned to primary surgery), while 22% were overstaged (being wrongly assigned to neoadjuvant treatment). Overall, correct decisions between primary surgery and neoadjuvant treatment based on EUS results were made in only 55/123 patients. In the event that the treatment strategy had depended solely on EUS results, 27% of the patients would have been wrongly treated by primary surgery, because histopathology showed more advanced tumor stages, and 49% of the pat...