Identifying baseline rectal MRI features as predictive indicators for local recurrence and metastatic disease in rectal cancer treated with surgical resection and neoadjuvant therapy or surgical resection alone

To identify baseline rectal MRI characteristics that may serve as predictive factors for recurrence in patients with rectal adenocarcinoma after surgical resection.

This retrospective, single-center study included 269 consecutive patients (median age, 55 years [interquartile range, 47-65]; 144 men and 125 women) diagnosed with rectal cancer from January 2015-December 2017 who underwent baseline rectal MRI followed by surgical resection. MRI characteristics were collected from rectal MRI synoptic reports. Recurrence-free survival was defined as the time between surgical resection and recurrence (local recurrence and/or metastatic disease) or death. Statistical analysis included Cox proportional hazards to determine associations between baseline rectal MRI/clinical characteristics and recurrence.

The median recurrence-free survival in the study sample was 6.4 years. Baseline rectal MRI characteristics associated with recurrence at univariable analysis were: age > 55 years (P = 0.044), low rectal tumor location (P = 0.04), craniocaudal length ≥ 5.0 cm (P = 0.007), anal canal involvement (P = 0.011), presence of suspicious total mesorectal excision (TME) lymph nodes > 0.5 cm (P = 0.03), mesorectal fascia involvement (P = 0.04), T3 stage (P = 0.024), T4 stage (P = 0.008), and M1 stage (P = 0.024). At multivariable analysis, only age > 55 years (P = 0.012) and the presence of suspicious TME lymph nodes > 0.5 cm (P = 0.049) remained associated with recurrence.

Advanced age and the presence of suspicious TME adenopathy > 0.5 cm on baseline rectal MRI are associated with higher risk of recurrent disease in patients with resected rectal cancer.