PET CT Predicts Oesophageal Adenocarcinoma Residual Disease Risk

Oesophageal adenocarcinoma imaging predicts likelihood of residual disease after surgery and chemoradiotherapy

medwireNews: Positron emission tomography computed tomography (PET CT) results indicate that the imaging technique can help identify patients with locally advanced oesophageal adenocarcinoma who are at risk of residual disease after trimodal therapy.

The study, published in JAMA Surgery, revealed significant differences in pre- and post-therapy 18F-fluorodeoxyglucose uptake between the 22 patients who had a complete pathological response (CPR) after surgery and chemoradiotherapy and the 55 patients who had an incomplete pathological response (IPR).

CPR patients had significantly higher values than IPR patients for their average prestandardised uptake value (SUV) variable (14.5 vs 11.2), change in SUV (10.3 vs 5.4) and the relative change in SUV (0.6 vs 0.4).

Further analysis indicated that a decrease in SUV of less than 45% was reliably associated with the presence of residual disease, with a positive predictive value of 91.7%, report Steven Hochwald, from Roswell Park Cancer Institute in Buffalo, New York, USA, and co-authors.

However, the change in SUC cutoff value did not reliably predict the likelihood of a CPR, with a positive predictive value of just 38.0%.

Nor did PET uptake characteristics significantly predict overall, disease-specific or recurrence-free survival in the patients.

“Based on the findings from our study, the current recommendation is still surgical resection regardless of the posttherapy PET SUV in the primary tumor”, the researchers conclude.

“However, our study highlights the ability to detect patients with residual disease and the need to critically evaluate these patients for consideration of additional therapies.”

P Marco Fisichella, from Brigham and Women’s Hospital in West Roxbury, Massachusetts, USA, praises the “near-ideal conditions” of the study, designed to eliminate bias and variability, in an accompanying comment.

However, he notes it is difficult to generalise the results due to the small number of patients, the single institution setting, the non-validated definition of pathological response and the significant variation in interval length between PET CT imaging.

“Therefore, the findings… although promising, suggest that the real value of the PET CT may be limited to the diagnosis of metastatic or recurrent disease”, writes P Marco Fisichella.

“In addition, another potential application of PET CT could be to predict the response of a patient to neoadjuvant therapy by performing the test 2 weeks after initiation of chemotherapy and radiation, as suggested by the results of the Metabolic response evaluation for individualization of neoadjuvant chemotherapy in the esophageal and esophagogastric adenocarcinoma phase 2 trial.”

References

Kukar M, Alnaji RN, Jabi F, et al. Role of repeat 18F-fluorodeoxyglucose positron emission tomography examination in predicting pathologic response following neoadjuvant chemoradiotherapy for esophageal adenocarcinoma. JAMA Surg 2015; Advance online publication 22 April. doi:10.1001/jamasurg.2014.3867

Fisichella PM. Indications and limitations in the management algorithm of patients with esophageal adenocarcinoma. Positron emission tomography computed tomography. JAMA Surg 2015; Advance online publication 22 April. doi:10.1001/jamasurg.2015.0392

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