BBNラット膀胱癌における膀胱部分切除術の影響

Abstract

1) 0.05%BBNをウィスター系雄ラットに経口投与することにより膀胱癌を発生せしめたうえで膀胱部分切除術を加え術後の組織像を経時的に検討した.2)膀胱癌形成達成後, 膀胱部分切除術を加えたBBNラットは高頻度に浸潤癌を形成した.3)膀胱部分切除術を加えたBBNラット膀胱癌はヒト膀胱浸潤癌のよいモデルである.4)手術創の治癒機転でのDNA新生の腫瘍の悪性化に対する影響が示唆された

Experimental induction of bladder cancer using N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) is a well-established technique because of its convenience and reliability. However, most BBN-induced rat bladder tumors are superficial growths and are not usually considered a suitable model for deeply invasive human bladder cancers. We administered rats BBN for 20 weeks by mixing it in the drinking water at a concentration of 0.05%. The tumor which developed in the bladder was mechanically irritated by partial cystectomy, and the tumor was observed at intervals. Deeply invasive tumors developed with a high incidence after 6 weeks (75% 6 weeks after the partial cystectomy, 85% after 8 weeks and 71% after 12 weeks). In contrast, the incidence was 0% in the prepartial-cystectomy group, 8% in the control group and 22% 4 weeks after the partial cystectomy. The tendency for superficial tumors to become deeply invasive after 6 weeks was significant (p less than 0.005). No infiltration was seen in other organs including the prostate. The malignancy of the tumors was G1 and G2 at 0 week after the partial cystectomy, and G2 and G3 at 4, 6, 8, and 12 weeks. The rat bladder cancers induced by BBN in our experimental system seem to be a good model for deeply invasive human bladder cancers in terms of both the depth and malignancy of the cancers. In a clinical study on patients who underwent partial cystectomy, the recurrence rate was high, i.e., 50%, while mortality was as high as 40% or more in the high-stage and high-grade tumor group.(ABSTRACT TRUNCATED AT 250 WORDS)