A histopathological comparison of changes after neo-adjuvant radiotherapy in rectal cancer / 医学研究生学报

ABSTRACT

Objective: To compare the histopathological changes after neo-adjuvant radiotherapy and to elucidate the mechanism of radiotherapy in rectal cancer. Methods: 80 patients with rectal cancer in pTNM stage Ⅱ or Ⅲ were enrolled between April 2000 and December 2002.They were randomly assigned to surgery alone or preoperative neo-adjuvant radiotherapy.The conventional radiotherapy scheme was followed 40 Gy in 2.0 Gy fractions.The treatment last 4 weeks and it is usually followed by an interval of 1-2 weeks before the operation.Pathological changes including necrosis of tumor and changes of matrix and vessels were graded. Results: Significant tumor regression(RCRG 1) was seen in 14 cases(35 percent) after radiotherapy,while partially tumor regression(RCRG 2) was seen in 18 cases(45 percent).Significant necrosis was observed in 72.5 percent of cases after preoperative radiotherapy,most foci of adenocarcinoma were replaced by fibrosis in 80 percent of cases,and intimal thickening in most of the vessels were seen in 77.5 percent of cases.The frequency of these pathological changes after radiotherapy was significantly more than control group. Conclusion: Necrosis,fibrosis and thickening of vascular intima in the rectal cancer tissue after radiotherapy is more frequent than those without radiotherapy.It may be the potential reason for increased resection rate and sphincter-saving after radiotherapy.