Background and aims: Submucosal invasion of superficial esophageal cancer (SEC) is related to the prognosis. We prospectively analyzed outcomes of SEC in patients staged by endoscopic ultrasonography (EUS).
Patients and methods: We staged 31 endoscopically diagnosed SEC cases using a 20/15-MHz thin probe. The EUS tumor stage was classified as EUSM (limited within mucosa), EUS-SM (with submucosal invasion), or EUS-MP over (invading the muscularis propria or deeper). Lymph node metastasis and 2-yr survival were analyzed according to the EUS tumor stage in 29 squamous cell carcinoma cases. Interobserver agreement of the EUS stage was tested between the examiner and a blind reviewer.
Results: Lymph node metastasis was significantly frequent in the EUS-SM group (8 of 18 cases [44.4%]) compared with the EUS-M group (1 of 10 cases [10%]) (p = 0.03). Patient survival at 2 yr after initial therapy was 72.2% in the EUS-SM group and 90% in the EUS-M group. Death from cancer was noted only in the EUS-SM group (three cases). The accuracy rates of EUS tumor staging were 74.1% by the examiner and 66.7% by the blind reviewer, with moderate interobserver agreement (kappa = 0.46).
Conclusions: Thin-probe EUS can classify SEC into two groups: the EUS-M group with excellent outcome and the EUS-SM group with a significant risk of lymph node metastasis.