Pathological changes of advanced lower-rectal cancer by preoperative radiotherapy.

BACKGROUND/AIMS: In the treatment of lower rectal cancer, we examined the pathological effects of preoperative radiotherapy on intramural spread of tumor and risk factors for local recurrence, including tumor deposit, budding growth of primary tumors, and micrometastasis to lymph nodes.

METHODOLOGY: Ninety-four patients who underwent surgery for lower rectal cancer were selected. Forty-seven patients received preoperative radiotherapy, at a total dose of 50 Gy [Rad(+) group], whereas 47 did not [Rad(-) group]. Intramural spread was evaluated between the Rad(+) and Rad(-) groups. For analysis of tumor deposit, budding, and micrometastasis, 25 stage-matched patients were selected in both groups.

RESULTS: Intramural spread was significantly less in the Rad(+) group, compared with the Rad(-) group. The Rad(+) group showed a significant decrease in tumor deposit, budding, and micrometastasis, compared with the Rad(-) group. In patients having overt lymph node metastases or not, the tumor deposit and budding were significantly higher in patients having overt metastases, compared with those not having them, in the Rad(-) group, whereas there was no significant difference in the Rad(+) group.

CONCLUSIONS: Intramural spread and tumor deposit, budding, and micrometastasis were significantly decreased in the Rad(+) group, compared with the Rad(-) group. These results suggested effects of preoperative radiotherapy for sphincter preservation, as well as for decreasing the local recurrence rate.