Cell proliferation in carcinoma in bilharzial bladder: influence of pre-operative irradiation and clinical implications.

Cell proliferation in carcinoma in the bilharzial bladder was studied in 92 patients in terms of the in vitro labeling index (LI), cell density (CD) and labeled cell density (LCD) using the in vitro 3H-Tdr technique. Cell proliferation was much greater in high than in low grade tumors and in deep than in superficial parts of the tumor, but was much less dependent on cell type; transitional cell cancer had the highest activity followed by squamous cell and adenocarcinoma. The probability of local recurrence after cystectomy decreased markedly when the LI exceeded 5.0%. The influence of the following three pre-operative radiotherapy regimens was studied: split-course (SC): the initial course consisted of 20 Gy in 10 treatments with a similar course was given after one week, hyper-fractionation using 17 treatments 0.6 Gy each on two successive days, this 2-day course of 20 Gy was repeated after one week, and concentrated irradiation consisting of two treatments, 6.0 Gy each with a gap of one week. Cystectomy was performed 14-20 days after treatment in all groups. Preoperative irradiation was generally associated with an increased probability of local control. The unfavorable influence of a high pretreatment LI was not noted after pre-operative irradiation. The CD was also reduced in proportion to the pretreatment LI. It is proposed that the response to irradiation was proportional to the initial proliferation activity and hence the prognostic significance of tumor grade and pretreatment LI was masked. Postirradiation tumor volume reduction was a strong predictor of treatment outcome. Concentrated irradiation was the least efficient pre-operative irradiation regimen and was associated with the least tumor volume reduction.