TUMOR RESPONSE TO NEOADJUVANT LONG-COURSE CHEMORADIOTHERAPY DEPENDS ON THE RECTAL CANCER PATIENT GENDER.

Our study aimed to analyze the correlation of cancer-related parameters with tumor regression grade (TRG) and disease-free survival (DFS) by gender in 192 rectal cancer patients operated on after neoadjuvant long-course chemoradiotherapy (LCCRT). Preoperative diagnostics revealed no significant gender differences in any clinical parameters other than obesity (p=0.031). We found that slightly overweight men had a lower incidence of distant metastases (p=0.042). The post-LCCRT pathologic finding showed that women had more positive lymph nodes (ypN, p=0.002) while no other pathologic parameter differed significantly between the genders. Overall, a poor response to therapy correlated with a shorter time to disease progression (p=0.002). Women achieved ypN0 in 50% of cases, but only 27% had a good TRG compared to 40.5% of men (p=0.073). Women had a worse DFS than men, even when complete response to therapy was achieved (p=0.003), and greater depth of residual tumor invasion (ypT, p=0.035) and higher ypN (p=0.002) correlated with shorter DFS. Positive resection margins (p<0.001), higher ypN stage (p=0.003), and poor TRG (p=0.025) correlated with shorter DFS in men. We conclude that women have a poorer response to LCCRT with the possibility that therapeutic approach to the neoadjuvant treatment of rectal cancer may be gender-specific.