RESULTS

Assessment of T-status

An assessment of mural penetration and nodal status was possible in all patients including 12 (21.8%) patients in whom malignant stenosis precluded passage of the echoendoscope. In the latter patients, the probe was positioned at the superior edge of the tumor and wall penetration, as well as peritumoral node status, was partially assessed.

EUS correctly staged 7/11 (63%) patients with T₁ lesions; three were overstaged to T₂ and the tumor was not seen in one patient (T_X). Eight patients had lesions partially invading the muscularis propria (T₂), of whom five (62%) were correctly staged. Two of the remaining three patients were overstaged to T₃ and one understaged as T_is. Transmural tumors (T₃) were present in 34 patients of whom 24 (70.5%) were correctly identified by preoperative EUS. Among the remaining ten patients, eight were understaged as T₂ and two were overstaged as T₄. The two patients with T₄ lesions were correctly staged by EUS. Among twelve patients in whom the passage of echoendoscope was not possible, 11 (91%) had T₃ tumors. The sensitivity, specificity, positive and negative predictive values for T-stage assessment are shown in Table 3.

Assessment of nodal, status

The average number of resected nodes was 32 nodes per patient. The absence of nodal metastases was confirmed pathologically in 18 patients of whom 12 (66%) were correctly identified by EUS preoperatively. The impact of operator experience was particularly evident in this instance. A correct assessment of negative nodal status was achieved in 91% of patients studied by a single physician. Among 37 patients with N₁, disease, 22 patients (59%) were correctly staged preoperatively. The sensitivity, specificity, positive and negative predictive values for N-stage assessment are shown in Table 3.

Correlation of T-stage with N₁disease

There was a progressive increase in the frequency of nodal metastases with increasing depth of wall penetration by the tumor. Metastatic nodal disease was present in 3/11 T₁ lesions (30%), 5/8 T₂ lesions (62%) and 28/34 T₃ lesions (82%). Among patients with malignant stenosis precluding passage of the echoendoscope, 11/12 (91.5%) had positive nodes.

Stage assessment

In predicting the overall tumor-lymph node-metastases (TNM) stage, EUS was correct in 34 patients (Table 4). Staging was best for patients with Stage I and Stage III disease but was poor for patients with Stage II tumors. Importantly, 11/17 patients (64%) with the Stage I or IIA tumors were correctly staged while 36% were overstaged. Overstaging was again reduced to 11% in the subset of patients studied by a single operator.