[Pathological changes of rectal cancer after irinotecan, 5-fluorouracil or combined short-term radiotherapy]

To observe and evaluate the pathologic changes and curative effects of irinotecan (CPT-11), 5-fluorouracil (5-FU) and combined short-term radiotherapy before low-set rectal cancer operation so as to provide a theoretic basis for formulating a new effective adjuvant therapeutic regimen.

A total of 41 patients of low rectal cancer were treated with CPT-11, 5-FU therapy or CPT-11 plus 5-FU combined short-term radiotherapy from April 2002 to April 2009. They were divided into 2 groups according to different treatment schemes, including irinotecan group (n = 18) and irinotecan combined short-term radiotherapy group (n = 23). The pathologic changes before and after treatment were observed and the differences of two treatment approaches compared.

Tumor cells had different degrees of degeneration and necrosis under microscope in two groups. Compared with computed tomographic findings before therapy, tumor sizes of two groups were reduced by an average of 33.1% (13.5 mm vs 20.2 mm) and 34.4% (12.8 mm vs 19.5 mm) respectively. Two groups were graded according to the RCRG (rectal cancer regression grade) score: RCRG1: 7 cases vs 18 cases, RCRG2: 4 cases vs 3 cases and RCRG3: 7 cases vs 2 cases. According to the pathologic evaluation standard, 3-degree necrosis, cell interstitial fibrosis and intimal thickening in vessels were observed in two groups: 7 cases vs 17 cases, 6 cases vs 17 cases and 3 cases vs 14 cases respectively (all P < 0.05). Five patients achieved complete pathological remission in the irinotecan combined short-term radiotherapy group.

Based on the pathological changes and mitigation results after treatment, CPT-11 and 5-FU may be used as neoadjuvant drugs for rectal cancer. If the above two drugs can be used in combination with short-term radiation, the curative effect will be better.