705 Background: The interaction between host and tumour factors is an important determinant of long-term outcome following rectal cancer resection. At cellular level, hypoxia within the tumour microenvironment stimulates neovascularisation, alters tumour metabolism and is implicated in dissemination and metastases. At host level, restricted blood flow to the tumour may play a role in tumour hypoxia. Significant calcification of the distal aortic and iliac arteries could result in impaired rectal perfusion. We aimed to investigate the relationship between aortoiliac calcification (AC) and long-term outcome following rectal cancer resection. Methods: Patients were identified from a prospectively maintained database. Recurrence and survival data were abstracted. On staging CT images, the sum of calcified quadrants of the distal aorta and iliac arteries at the level of the bifurcation was calculated. ROC analysis was used to identify the optimum threshold for determining significant calcification. Results: Between 2008-2016, 181 patients with available CT scans underwent surgery for rectal cancer. Most were male (60%), aged over 65 (53%) and TNM stage II/III (72%). Median follow-up was 63 months. Significant AC was identified in 44 patients (24%). Recurrence occurred in 42 patients: local in 16 (9%) and systemic in 26 (14%) patients. Recurrence was associated with significant AC (p = 0.017), TNM stage (p = 0.002) and venous invasion (p = 0.006). When considering those with and without significant AC, there were differences in the rates of local (11% vs. 8%) and systemic (25% vs. 11%) recurrence respectively (p = 0.043). On univariate Cox regression analysis, overall survival was related to age (p = 0.012), ASA grade (p = 0.042) and significant AC (p = 0.001). On multivariate analysis, significant AC (p = 0.011) was the only independent predictor of overall survival. Conclusions: The burden of aortoiliac calcification appears to play an important role in influencing long-term outcome following rectal cancer resection, independent of traditional determinants such as TNM stage and ASA grade. While validation is required, further investigation of the mechanism underlying this relationship is warranted.
Long-Term Outcome of Rectal Cancer With Clinically (EUS/MRI) Metastatic Mesorectal Lymph Nodes Treated by Neoadjuvant Chemoradiation: Role of Organ Preservation Strategies in Relation to Pathologic Response
