Correlation of rectal tumor volumes with oncological outcomes for low rectal cancers: does tumor size matter?

Purposes: Several reports have described a relationship between tumor volume and oncological outcomes for certain cancers. There is paucity of similar data for rectal cancer. We conducted this study to establish whether tumor volume, mesorectal volume, and the tumor volume to mesorectal volume ratio (TV/MRV), evaluated by magnetic resonance imaging (MRI), affect the oncological outcomes of patients with rectal cancer.

Methods: We performed volumetric analysis of rectal tumors from magnetic resonance imaging (MRI) images and assessed their correlation with oncological outcomes, using clinical and radiological databases.

Results: The subjects of this study were 25 of 35 patients who underwent rectal cancer surgery after staging with MRI, after the exclusion of 7 patients for whom MRI images could not be retrieved and 3 patients who had metastases identified at diagnosis. Tumor volume (TV) was a significant predictor of overall survival hazard ratio (95% CI); 5.8 (1.2-29), (P = 0.03). Mesorectal volume (MRV) and TV/MRV did not correlate with oncological outcomes.

Conclusions: We found a direct relationship between tumor volume and overall survival, which may be used to stratify rectal tumors for neoadjuvant therapy. A larger prospective study is required to confirm this correlation.