Positron emission tomographic scanning predicts survival after induction chemotherapy for esophageal carcinoma

The ability to accurately predict clinical and pathological response and survival in patients undergoing preoperative chemotherapy may have a significant impact on treatment strategy for esophageal carcinoma. This study assessed the predictive accuracy of clinical response (CR) and positron emission tomography (PET) scanning in determining pathological downstaging and disease free survival (DFS) after chemotherapy.

This is a retrospective review of patients who underwent chemotherapy prior to complete surgical resection for esophageal carcinoma between 1999 and 2005. Clinical response was correlated with pathological downstaging and survival. For PET scanning, the percent reduction in maxSUV after induction therapy was determined and we identified the optimal threshold of percent reduction in maxSUV for predicting clinical response and pathological downstaging.

Sixty-two patients (52 men, median age 62.3) were evaluated. Thirty-nine patients (62.9%) had either a partial (n = 32) or complete clinical response (n = 7) to induction therapy. The sensitivity, specificity, positive, and negative predictive value of an objective clinical response in predicting downstaging in T and (or) N were 85.7%, 55.9%, 61.5%, and 82.6%, respectively. There was no difference in DFS between responders and nonresponders. The PET sensitivity, specificity, positive, and negative predictive values for predicting pathologic downstaging were 77.8%, 52.9%, 56.8%, and 75%, respectively. Thirty-seven patients (59.7%) had a 50% or greater reduction in the maxSUV of their primary tumor and had a significant improvement in DFS compared with patients with a less than 50% reduction in maxSUV (median DFS time: 35.5 months vs 17.9 months, respectively, p = 0.03). Significantly, 11 patients had a 100% reduction in maxSUV despite the presence of residual tumor.

Complete response and PET appear equivalent in predicting pathological downstaging. However, a 50% reduction in the maxSUV after induction therapy is more significantly associated with improved DFS than CR or pathological downstaging. Additionally, a complete absence of PET signal cannot be equated with a complete pathological response.