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Gastrointestinal Cancers
Figure 1: Endoscopic Ultrasound Image of T1 Esophageal Cancer
with N1 disease as classified by EUS have poorer survival than those with
Confined to Mucosa and Superficial Submucosa
N0 disease.
23
Additionally, the number of lymph nodes detected is a
predictor of overall survival.
24
EUS can be helpful in differentiating benign
from malignant lymph nodes. Criteria for malignant lymph nodes include
a round shape, diameter greater than 10mm, hypoechogenicity,
and nodes with a sharp border.
16
EUS is less accurate in identifying
malignant nodes than in evaluating depth of tumor invasion. The
accuracy of conventional EUS for N staging is 79%, as demonstrated by
a recent meta-analysis.
17
Studies comparing EUS with CT for regional lymph node metastasis have
revealed that EUS is more accurate for N staging. The utilization of EUS-
guided FNA has been shown to improve the accuracy of EUS for
N staging by providing cytology of lymph nodes.
25
In this prospective
Arrow indicates site of invasion.
study, EUS–FNA for lymph node metastases had a sensitivity and
specificity of 98 and 100%, respectively.
Figure 2: Endoscopic Ultrasound Image of T4 Esophageal Cancer
Invading the Pleura
Celiac Axis Lymph Node Staging
EUS plays a role in the evaluation of celiac nodal involvement and
determining M1 status. There is no role for EUS in the search for distant
metastases beyond this region.
2,3,12,13
In patients with esophageal cancer,
the identification of celiac lymph nodes (CLNs) indicates distant
metastasis. Regardless of echo features and size, up to 90% of all CLNs
detected by EUS are malignant.
26
One hundred percent of CLNs greater
than 1cm in size were malignant in this study. The clinical impact that
malignant CLNs have on therapy leads to the necessity of performing
EUS–FNA, providing proof of malignant involvement prior to neoadjuvant
therapy.
27
The detection of metastasis in celiac lymph nodes by EUS–FNA
has a reported sensitivity of 98% and a specificity of 100%.
26
Arrow indicates site of invasion.
Impact of Endoscopic Ultrasound on Esophageal Cancer
The clinical outcome of patients with esophageal cancer before and after
Figure 3: Endoscopic Ultrasound Image of a Metastatic
Paraesophageal Lymph Node (arrow)
the introduction of EUS has demonstrated that the use of EUS is
associated with an advantage in recurrence-free survival and overall
survival.
10,28
This benefit appeared to be related to the increased
administration of chemoradiotherapy through more accurate
pre-operative staging.
10
EUS changed the treatment strategy in 75% of
cases in two prospective trials, with a tendency toward less costly, less
risky, and less invasive management.
18,29
The most powerful impact of
EUS on the clinical management of patients with esophageal cancer is
the decision to proceed with a potential surgical curative resection. EUS
can accurately stage T4 tumors and thus refer these patients for palliative
treatment rather than a potentially morbid surgery.
30
Additionally,
patients with metastatic disease to the celiac trunk have a poor
prognosis, and it is doubtful whether these patients benefit from curative
mucosal resection. However, new EUS probes that operate at higher surgical resection.
3
The correlation of staging by EUS with the
frequencies (15 and 20MHz) increase the accuracy of differentiating recommended therapy for esophageal cancer is summarized in Table 1.
between T1 and T2 lesions to 92% from the 76% accuracy achieved with
standard EUS endoscopes. High-frequency probes can determine Endoscopic Ultrasound Staging After Neoadjuvant Therapy
whether superficial cancer is limited to the muscularis mucosa in 84% of With advanced loco-regional neo-adjuvant therapy, a combination of
cases, allowing high-frequency EUS to guide the application of pre-operative chemoradiotherapy can be offered to help decrease tumor
endoscopic resection for the management of superficial cancer.
21,22
burden. EUS performed to help determine response to therapy has been
demonstrated to consistently overstage patients with poor accuracy
Nodal (N) Staging (27–82%).
2,4,13,31,32
The most frequent error is overstaging, apparently
Owing to its rich lymphatic supply, esophageal cancer has the propensity because the fibrosis and inflammation associated with chemo-
to spread to local lymph nodes. It has been demonstrated that patients radiotherapy are indistinguishable from residual tumor on EUS imaging.
92 US GASTROENTEROLOGY REVIEW 2007
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