Effect of neoadjuvant therapy on cancer staging by endoscopic ultrasound

Neoadjuvant chemo- and/or radiotherapy (C/RT) may be given prior to resection of GI malignancies to attempt to achieve higher cure rates. The utility of endoscopic ultrasound (EUS) in assessing response to C/RT, and the effect of C/RT on EUS accuracy, are unknown. 19 patients with esophageal (n=12, Squamous 4, Adeno 8), rectal (6) or duodenal (1) cancer were treated with preoperative chemo (18 pts)(5-FU, Leukovorin, Adriamycin and/or Cisplatinum) and/or XRT (10 pts) prior to surgical resection and staging. 16 patients had EUS prior to C/RT, 17 patients following C/RT, 14 both. These results were compared to surgical patients with esophageal and rectal cancer who had undergone pre-operative EUS but had not received C/RT (Control). Comparing initial EUS to final surgical stage: T-Stage Improved No Change Worsened Response p-value C/RT 6 7 3 38% (Fisher) Control 8 34 10 15% 0.06 N-Stage C/RT 8 5 3 50% Control 7 44 5 13% 0.02 (Improved: EUS Stage > Surgical Stage, No Change: EUS Stage = Surgical Stage, Worsened: EUS Stage < Surgical Stage) Sub-group analysis demonstrated a significant effect on nodal stage for esophageal (response=44% v. 9%, p=0.03) and rectal cancer (67% v. 20%, p=0.03). EUS performed after C/RT significantly reduced staging accuracy resulting in an overall T-stage accuracy=31,% (v. Control=65%, p=0.017) and N-stage accuracy=50% (Control=79%, p=0.03), and for esophageal cancer T-stage accuracy=33% (v. Control=62%, p=0.09), N-stage accuracy=42% (Control=81 %, p=0.016). Conclusions: 1. C/RT may result in significant downstaging of GI malignancies. 2. EUS prior to C/RT may be used in conjunction with surgical staging to demonstrate the effectiveness of neoadjuvant therapy. 3. C/RT significantly decreases the accuracy of subsequent EUS staging. 4. Larger randomized studies are needed.