Using 18F-fluorodeoxyglucose positron emission tomography to monitor clinical outcomes in patients treated with neoadjuvant chemo-radiotherapy for locally advanced pancreatic cancer

Abstract

Background: Pancreatic cancer ranks as the fourth leading cause of cancer death in the United States with 5-year survival ranging from 1% to 5%. Positron emission tomography (PET) is a metabolic imaging system that is widely used for the initial staging of cancer and detecting residual disease after treatment. There are limited data, however, on the use of this molecular imaging technique to assess early tumor response after treatment in pancreatic cancer.

Methods: The objective of the study was to explore the relationship of early treatment response using the F-fluorodeoxyglucose (FDG) PET with surgical outcome and overall survival in patients with locally advanced pancreatic cancer. FDG-PET measurements of maximum standardized uptake value and kinetic parameters were compared with the clinical outcome.

Results: Twenty patients were enrolled in the study evaluating neoadjuvant induction chemotherapy followed by concurrent chemoradiotherapy (chemo-RT) for locally advanced pancreatic cancer. All 20 patients had prestudy PET scans and a total of fifty PET scans were performed. Among patients who were PET responders (> or =50% decrease in standardized uptake value after cycle 1), 100% (2/2) had complete surgical resection. Only 6% (1/16) had surgical resection in the PET nonresponders (<50% decrease). Two patients did not have the second PET scan because of clinical progression or treatment toxicity. Mean survival was 23.2 months for PET responders and 11.3 months for nonresponders (P = 0.234). Similar differences in survival were also noted when response was measured using Patlak analysis.

Conclusions: FDG-PET can aid in monitoring the clinical outcome of patients with locally advanced pancreatic cancer treated with neoadjuvant chemo-RT. FDG-PET may be used to aid patients who could have complete surgical resection as well as prognosticate patients' survival.

Figure 1

Overall survival curve for PET responders vs. non-responders using the Patlak model. The one long (and censored) survival time of 83.6+ months was truncated to 36 months to produce a more compact graph. The 1-year survival rate for the six PET responders was 87% (with 90% CL = ( 0.67, 1.00), and for the twelve PET non-responders was 28% (with 90% CL = ( 0.07, 0.49).

Figure 2

PET images of a PET responder (Patient 15) PET images show high FDG uptake in the pancreatic bed before treatment (scan 1), and improvement after 1 cycle of chemotherapy (scan 2) and after completion of chemo-RT (scan 3).