The effect of chemotherapy with or without radiation on the accuracy of MR imaging for evaluating tumor infiltration into the bladder wall in cases of advanced bladder cancer

Staging of tumor infiltration into the bladder wall is one of the critical points in decision-making for optimal treatment of invasive bladder cancer. We studied the correlation of MR findings with pathological diagnosis in cases of invasive bladder cancer which had been treated with chemotherapy, with or without radiation. Twenty-one patients (14 men and 7 women) with invasive bladder tumors who underwent either partial cystectomy or radical cystectomy were entered into the study. Eight cases had received chemotherapy after staging biopsy (Group A), 6 cases had undergone chemo-radiation therapy following staging biopsy (Group B), and 7 cases had received no adjuvant therapy except for staging biopsy preoperatively (Group C). All cases had MR imaging study before surgical treatment. The pathological stage was assessed by examining the whole layer of the resected bladder wall. Pathological diagnosis was pT0 in 4 cases, pT1 in 2 cases, pT2b in 5 cases, pT3a in 2 cases and pT3b in 8 cases. Staging with MR imaging was consistent with pathological findings in 14 of the 21 cases (66.7%), while MR imaging produced over-staging in 6 cases and under-staging in 1 case. Of the 6 cases with over-staging, 2 cases had received chemo-radiation therapy, 2 cases had received chemotherapy, and 2 cases had received staging biopsy alone preoperatively. The one case with under-staging had received chemo-radiation therapy preoperatively. The accuracy in staging with MR imaging was 75.0% (6/8), 50.0% (3/6), and 71.4% (5/7) in Groups A, B, and C, respectively. Imaging study with MR is useful for the staging of invasive bladder cancer. However, care should be taken in the staging of invasive bladder tumors which have been treated with chemotherapy, with or without radiation therapy, because inflammatory infiltration and/or fibrous change caused by the chemo-radiation make accurate staging with MR imaging difficult. (author)