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Introduction - Neoadjuvant chemoradiation is a part of multimodality management of locally advanced carcinoma esophagus. 18F FDG PET-CT(PET-CT) has been evaluated for assessing the response to neoadjuvant therapy and correlated with the prognosis in various studies with inconsistent results. We report our experience from prospectively collected data at tertiary referral center from North India.

Methods - We reviewed prospective data of 34 patients of potentially resectable squamous cell carcinoma esophagus from Feb 2010 to Nov 2011 at our institute. All patients (M:F 1.6:1 , mean age 51 years) had locally advanced squamous cell carcinoma of middle and lower 1/3rd esophagus (Stage T2-4NxM0) on initial staging with CECT thorax and abdomen ± PET-CT. Patients with good performance score underwent Neoadjuvant chemoradiation (NACRT) protocol including Cisplatin(30mg/m2) + 5FU(500mg/m2)from Day1 to Day4 and EBRT 30 Gy/10#/over 2 weeks. Restaging was done with PET-CT after >4 weeks after completion of NACRT. All resectable patients underwent transhiatal/ transthoracic esophagectomy without formal lymphadenectomy. Histomorphological regression was graded as per four tiered scheme described by CAP Cancer Protocol for Esophageal carcinoma (TRG 0 and 1 as complete and moderate response respectively and TRG 2 and 3 as minimal and poor response respectively)by single experienced pathologist blinded to clinical data. Post NACRT PET-CT Standard uptake value (SUVmax) and percentage change of SUVmax was correlated with tumor regression (TRG 0 and 1).

Results -Transhiatal esophagectomy was done in 30 patients and Transthoracic esophagectomy in 2 patients. Two patients had metastatic disease at surgery. Mean SUVmax was 13.6 and 6.45 for Pre NACRT and Post NACRT respectively suggesting metabolic response to therapy. Tumor regression (TRG 0 and 1) was seen in 12 (35.3%) patients. The percentage decrease in SUVmax >80% correlated with tumor regression with sensitivity, specificity, PPV, NPV and accuracy of 71.4%, 92.8%, 83.3%, 80% and 85.7% respectively. Post NACRT SUVmax <4.0 correlated with tumor regression with sensitivity, specificity, PPV, NPV and accuracy of 83.3%, 86.3%, 76.9%, 90.4% and 85% respectively

Conclusions- 18F FDG PET/CT is 85% accurate in response assessment of Neoadjuvant Chemoradiation for squamous cell carcinoma esophagus.

PET-CT images with complete metabolic response in a 72 year old male

Gross and Microscopic tumor regression (Complete pathological response) CAP TRG 0 in the same patient.