Objective: To investigate the appropriate distal resection margin in rectal cancer patients.
Methods: Thirty specimens of rectal carcinoma with total mesorectal excision(TME) were studied by flow cytometry and pathological examination. The differences of DNA ploidy status, DNA index (DI), proliferative index (PI), S-phase fraction (SPF) among rectal cancer, 3 cm and 5 cm below the tumor, normal rectum, distal mesorectum 3 cm and 5 cm below the tumor, and normal colon mesentery were analysed by flow cytometry, and were compared with the data of pathological examination.
Results: Pathological examination showed that there was no tumor invasion 3 cm and 5 cm below the tumor,but the metastasis rates of distal mesorectum 3 cm and 5 cm below the tumor were 26.7% and 6.7% respectively. The DI, PI and SPF of rectal cancer by flow cytometric examination were significantly higher than those of distal rectum 3 cm and 5 cm below the tumor, and normal rectum (P<0.05). The DI, PI and SPF of distal rectum 3 cm below the tumor were also significantly higher than those of distal rectum 5 cm below the tumor, and normal rectum (P<0.05), but there were no significant differences between DI, PI and SPF of distal rectum 5 cm below the tumor and those of normal rectum (P>0.05). The rate of DNA aneuploid of tumor was significantly higher than those of normal rectum and distal rectum 5 cm below the tumor,but there was no significant difference between the rate of DNA aneuploid of tumor and that of distal rectum 3 cm below the tumor. The DI and DNA aneuploid of rectal cancer and distal mesorectum 3 cm and 5 cm below the tumor were significantly higher than those of normal mesorectum,but there were no significant differences between DI and DNA aneuploid of rectal cancer and those of distal mesorectum 3 cm and 5 cm below the tumor. The PI and SPF of rectal cancer were significantly higher than those of normal mesorectum and distal mesorectum 3 cm and 5 cm below the tumor.
Conclusions: Rectal cancer is able to invade distal rectum 3 cm below the tumor and distal mesorectum 5 cm below the tumor, and radical resection of rectal cancer should beyond that range.