Eligible studies assessed the accuracy of 18F-FDG-PET for prediction of tumour response to neo-adjuvant therapy in patients with locally advanced rectal cancer as defined by histological diagnosis of adenocarcinoma of the rectum. Studies were required to use pathological outcome as the reference standard and to include more than 10 participants. Studies were excluded if they did not report sufficient data to enable calculation of accuracy estimates.
Included studies were conducted between 1997 and 2009. Approximately 60% were conducted in Europe; the rest were in USA, Australia, Japan and Korea. The mean age of study participants ranged from 50.5 to 67 years. Most participants were male. Neoadjuvant therapy regimens varied widely between studies (details reported in the article).
18F-FDG dose and definition of a positive imaging test varied between studies (studies used definitions based on standardised uptake value, response index or visual response; details were reported in a supplementary appendix). All included studies used histological grade or TNM Classification of Malignant Tumours criteria to define response.
Two reviewers independently assessed studies for inclusion. Any disagreements were resolved by discussion with a third reviewer.