Isoantigens A, B and H in urinary bladder carcinomas following radiotherapy.

ABH tissue isoantigens were measured by the Specific Red Cell Adherence (SRCA) test in 66 surgical specimens of urinary bladder, including 53 transitional cell carcinomas, 2 squamous cell carcinomas and 11 controls. The SRCA test was strongly positive in 10 of 11 controls. ABH isoantigens were absent or equivocally present in 68 percent of noninvasive carcinomas (stage 0) and in 65 percent of invasive carcinomas. Clinical histories revealed that all patients with invasive carcinoma who had strongly positive SRCA test results had received prior radiotherapy to the bladder region. None of the patients with invasive bladder carcinoma with negative or weakly positive SRCA tests had been radiated. Histopathology of tumors in both groups was similar. Results of this retrospective study support the hypothesis that radiation may induce differentiation in tumors, possibly through an enhancement of Golgi apparatus function. The SRCA test should not be used as a predictor of the biological behavior of future recurrences in patients with bladder carcinoma who have received therapeutic radiation since radiation may produce "false positive" SRCA test results.