The lack of evidence for PET or PET/CT surveillance of patients with treated lymphoma, colorectal cancer, and head and neck cancer: a systematic review.

UNLABELLED: PET and PET/CT are widely used for surveillance of patients after cancer treatments. We conducted a systematic review to assess the diagnostic accuracy and clinical impact of PET and PET/CT used for surveillance in several cancers.
METHODS: We searched MEDLINE and Cochrane Library databases from 1996 to March 2012 for English-language studies of PET or PET/CT used for surveillance of patients with lymphoma, colorectal cancer, or head and neck cancer. We included prospective or retrospective studies that reported test accuracy and comparative studies that assessed clinical impact.
RESULTS: Twelve studies met our inclusion criteria: 6 lymphoma (n = 767 patients), 2 colorectal cancer (n = 96), and 4 head and neck cancer (n = 194). All studies lacked a uniform definition of surveillance and scan protocols. Half the studies were retrospective, and a third were rated as low quality. The majority reported sensitivities and specificities in the range of 90%-100%, although several studies reported lower results. The only randomized controlled trial, a colorectal cancer study with 65 patients in the surveillance arm, reported earlier detection of recurrences with PET and suggested improved clinical outcomes.
CONCLUSION: There is insufficient evidence to draw conclusions on the clinical impact of PET or PET/CT surveillance for these cancers. The lack of standard definitions for surveillance, heterogeneous scanning protocols, and inconsistencies in reporting test accuracy preclude making an informed judgment on the value of PET for this potential indication.