Profiling of rectal cancers MRI in pathological complete remission states after neoadjuvant concurrent chemoradiation therapy

AIM: To fully characterise the magnetic resonance imaging (MRI) traits of rectal cancers in a large sample of patients, each experiencing pathological complete remission (pCR) after neoadjuvant concurrent chemoradiation therapy (CCRT). MATERIALS AND METHODS: A total of 120 patients (77 male, 43 female; median age, 59.5 years; range, 32-81 years) with rectal cancers in CCRT-induced pCR states who underwent pre- and post-CCRT MRI and eventual surgery between July, 2005 and September, 2014 were retrospectively reviewed. In most (n=100), diffusion-weighted imaging was also performed. Tumour volume, tumour regression grade (TRG), T-stage, mesorectal fascia (MRF) status, and T2 signal intensity (T2-SI) were analysed. Paired t-test and McNemar's test were applied for statistical comparisons. RESULTS: Tumour volume declined sharply after CCRT (pre-CCRT, 21.5 ± 22.4 cm(3); post-CCRT, 6.6 ± 8.4 cm(3); p