Rectal Cancer in Patients with Hereditary Nonpolyposis Colorectal Cancer Compared with Sporadic Cases: Response to...

This study aimed to assess the effect of neoadjuvant chemoradiation (nCXRT) on tumor regression and oncologic outcome of middle and low rectal cancer in patients of hereditary nonpolyposis colorectal cancer (HNPCC) compared to sporadic cases.

This was a retrospective cohort study that compared the outcomes of patients with HNPCC presenting with middle or low rectal cancer indicated for nCXRT vs patients with sporadic rectal cancer. All patients received long-course nCXRT followed by total mesorectal excision. Primary outcome was pathologic tumor regression grade (TRG) assessed after resection. Secondary outcomes included disease-free survival and overall survival.

Fifty-eight patients with HNPCC (24 female) were included in the study matched with 58 patients with sporadic rectal cancer (out of 166 using propensity score matching). Patients with HNPCC and sporadic rectal cancer were matched regarding tumor pathology TNM stage and lymphovascular invasion. In the HNPCC group, 36 patients (62%) had tumor regression (TRG3 = 6 (10.3%); TRG2 = 12 (20.6%); TRG1 = 18 (31%)) compared to 52 patients (92%) who had tumor regression in the control group (TRG4 = 9; TRG3 = 15; TRG2 = 18; TRG1 = 10) (p < 0.0007). After a median follow-up of 48 months, survival analysis revealed higher local recurrence and lower overall survival in patients with HNPCC compared to patients with sporadic rectal cancer.

Rectal cancer in patients with HNPCC showed poorer response to nCXRT and was followed by higher local recurrence and lower overall survival than patients with sporadic rectal cancer. Tumor regression was detected in <65% of patients with HNPCC compared to >90% of patients with sporadic rectal cancer, and none of patients with HNPCC had a complete response.