Positron emission tomography and pathological evidence of response to neoadjuvant therapy in adenocarcinoma of the esophagus

Abstract

Our aim was to determine if fluorodeoxyglucose positron emission tomography (FDG-PET) could be correlated with a pathological response in patients with esophageal adenocarcinoma receiving neoadjuvant chemotherapy and/or chemoradiation therapy. Patients with resectable, histologically proven adenocarcinoma of the esophagus were entered in the study. Preoperative chemotherapy comprised two cycles of cisplatin and 5-fluorouracil. Radiation therapy commenced with the second cycle on day 22. FDG-PET images were obtained pre-treatment and on completion of intended neo-adjuvant treatment. Quantification was achieved by the calculation of both standardized uptake values (SUV) and tumor/liver ratios (TLR). Evidence of histopathological response was identified according to the Mandard tumor regression scoring system. There were 45 patients, 22 receiving neoadjuvant chemotherapy and 23 chemoradiation therapy. Forty patients underwent surgical resection. Seven patients (16%) had a histopathological response. The mean percentage change in SUV in the histological responders group was -56.8% (SD 29) and in the non-responders -27.8% (SD 32.1) (P = 0.035). The mean percentage change in TLR was -49.1% (SD 44.8) in the responders and in the non-responders -27.3% (SD 31.3) (P = 0.128). There was no difference between the two methods of assessment, however there was less variation with SUV. There was no correlation between the FDG-PET response and the histopathological response. Presently an FDG-PET scan performed 3-6 weeks after neoadjuvant therapy for adenocarcinoma of the esophagus should not be used as a marker of the potential result of the treatment. The optimal timing of a second FDG-PET remains unclear.

Positron emission tomography for monitoring response to neoadjuvant therapy in patients with oesophageal and gastro-oesophageal junction carcinoma

“…Irrespective of whether chemotherapy or chemoradiotherapy was given, change in SUV was unable to distinguish pathological responders from non responders, although this may be influenced by the limited number of responders (n=1 chemotherapy, n=6 chemoradiotherapy). This however reflects realistic response rates to neoadjuvant therapies [3].…”

“…The differences between the studies may be in part explained by differing tumour types, tumour locations and neoadjuvant therapy and [43] demonstrated that a complete metabolic response did not equate to a complete pathological response. Smithers et al [3] looked at both neoadjuvant chemotherapy and chemoradiotherapy in adenocarcinomas of the oesophagus and GOJ with PET performed three to six weeks post completion of therapy. Irrespective of whether chemotherapy or chemoradiotherapy was given, change in SUV was unable to distinguish pathological responders from non responders, although this may be influenced by the limited number of responders (n=1 chemotherapy, n=6 chemoradiotherapy).…”

“…The majority of studies [3,[29][30][31][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49] have based or part based PET responses according to pathological criteria for determining response, either using reported pathological scoring systems [22,23] or with modifications to these systems. The…”

“…The poor response of tumours (in terms of pathological response and survival), at or around the gastro-oesophageal junction, to neoadjuvant therapy [1][2][3] suggests the need to predict or identify responders to neoadjuvant therapy at an early stage is paramount.…”

Evaluation of response: is 18F-FDG PET the answer?

“…It must be underlined that other authors [8][9][10] were already critical of the use of 18 F-FDG PET in making important clinical decisions on patient treatments.…”