Pancreatic carcinoma is common in the United States, with approximately 30,000 patients each year diagnosed with pancreatic adenocarcinomas. Patients with inflammatory processes in the pancreas (pancreatitis) but no cancer can sometimes have high FDG uptake that is indistinguishable from cancers and, thus, must be differentiated from patients with cancer. FDG PET is being applied increasingly in pancreatic cancer diagnosis.
A recent literature review of all available studies found this:
For diagnosis: An estimated 50% change was noted in management effect, based on 26 patient studies. For diagnosis/staging: An estimated 43% change was noted in management effect, based on 65 patient studies. For staging: An estimated 36% change was noted in management effect, based on 33 patient studies. For recurrence: An estimated 53% change was noted in management effect, based on 19 patient studies. For monitoring response: An estimated 16% change was noted in management effect, based on 19 patient studies.
Considering the very poor prognosis of pancreatic carcinomas, PET´s greatest role may prove to be in helping to characterize masses appearing in the pancreas, as opposed to more general tumor staging. This is an active area of current investigation.
In terms of distinguishing between benign and malignant disease, the gold standard is percutaneous or open biopsy. If PET were to be used to allow patients with scans suggesting benign masses to avoid biopsy, a very high negative predictive value would be required. The key statistic underlying the negative predictive value is the false negative rate. Patients with false negative results are incorrectly assumed to have benign disease, and are thus not promptly treated for pancreatic cancer. Based on the literature review, the negative predictive value ranged between 75% and 92%, depending on an underlying prevalence of disease ranging from 50%-75%. This level of diagnostic performance may not be adequate to recommend against biopsy. The gold standard is endoscopic ultrasound.NCCN does not recommend PET in the initial workup. On p. PANC-A(2011) it says: “The role of PET/CT remains unclear. PET/CT may be considered after formal pancreatic protocol in high risk patients to detect extra-pancreatic massess. It is not a substitute for high quality contrast enchanced CT”.
The use to diagnose should be considered investigational. Special care is needed to avoid false positives that are common from infection and inflammatioin in this area.
A 2009 guideline says: ” At this time, there are insufficient treatment options that improve the outlook in patients who recur after surgical resection that would allow PET to contribute to management. PET imaging in recurrent disease should be restricted to clinical trials.”
A recommendation cannot be made for or against the use of PET to guide clinical management based on assessment of treatment response due to insufficient evidence.
PET is not recommended for clinical management of suspected recurrence, nor for restaging at the time of recurrence, due to insufficient evidence and lack of effective therapeutic options.
NCCN advises suveillance 3-6 months for 2 years, then annually, but with CT and not PET.
Matchar DB, Kulasingam SL, Havrilesky L, et al. and the Duke Center for Clinical Health Policy Research and Evidence Practice Center. Positron emission testing for six cancers (brain, cervical, small cell lung, ovarian, pancreatic and testicular). Technology Assessment. Prepared for the Agency for Healthcare Research and Quality (AHRQ). Rockville, MD: AHRQ; February 12, 2004.
Kanjeekal S, Biagi J, Walker-Dilks C. PET imaging in pancreatic cancer: recommendations. Toronto (ON): Cancer Care Ontario (CCO); 2009 Jan 19. 20 p. (Recommendation report – PET; no. 5). [34 references]
Ana Beatriz Kinupe Abrahao, Yee Ung, Yoo-Joung Ko, Scott R. Berry; FDG PET/CT in pancreatic cancer staging and management: A retrospective study. Journal of Clinical Oncology 35, no. 4_suppl (February 2017) 464-464.
M. Ducreux et al, Cancer of the pancreas: ESMO Clinical Practice, Guidelines for diagnosis, treatment and follow-up. Annals of Oncology
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