Background Endoscopic ultrasound (EUS) is established as the most accurate method currently available for determining the depth of primary cancer invasion (T stage). Standard EUS criteria may not be accurate in assessing depth of cancer invasion and nodal status after patients have received chemotherapy or radiotherapy due to residual fibrosis and inflammation. Mathods We conducted a prospective study to determine if EUS estimation of tumor size could be used to assess response to preoperative adjuvant chemoradiation. Using EUS, TNM stage was assessed on 31 patients (22 men: 9 women; mean age = 62 yrs) with cancer of esophagus or cardia (19 adenocarcinoma, 12 squamous cell cancer) prior to initiation of combined radiation and 5-FU/cisplatin (and/or carboplatinum) chemotherapy. The cross-sectional area (MAX) of the tumor in the transverse plane at the location where the tumor had maximal thickness was calculated to estimate tumor size. EUS staging and measurement of MAX were repeated at completion of adjuvant therapy just prior to surgery. Response to preoperative adjuvant chemoradiation was defined as 50% reduction in MAX. Surgical staging was compared between responders and nonresponders. Results Eight patients who did not undergo surgery were excluded from analysis. EUS T stage in the remaining 23 patients prior to therapy was as follows: 3 T2, 16 T3, and 4 T4. Following chemoradiation, EUS T staging was changed in 6 pts (3 T4 downstaged to T3,2 T3 downstaged to T2, and 1 T3 downstaged to T1). At surgical pathology, 3 pts had no residual tumor in the esophagus (T0), 5 had T1, 3 had T2, 10 had T3, and 2 had T4 tumors. EUS T staging accuracy following adjuvant therapy was only 43%. MAX decreased from a mean of 5.5 +/- 2.4 sq cm to 1.6 +/- 0.9 sq cm in responders, whereas MAX went from 7.0 +/- 3.0 sq cm to 5.4 +/- 2.2 sq cm in nonresponders (p=0.009 using Wilcoxon rank-sum statistics). 10/13 patients with at least a 50% reduction in MAX (responders) had T0, T1, or T2 tumors at surgery whereas 9/10 nonresponders had T3 or T4 tumors at surgery (p=0.001 using likelihood chi-square statistics). There was no difference in T stage between responders and nonresponders prior to chemoradiation. Conclusions  standard EUS staging criteria are not accurate after adjuvant chemoradiation,  reduction in maximal cross-sectional area (MAX) of tumor appears to be a more useful measure for assessing response of esophageal cancer to preoperative adjuvant chemoradiation, and  responders (patients with a > 50% reduction of MAX) have an increased likelihood of downstaging at surgery than nonresponders.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging