Radiotherapy (2500 rad) for testicular leukemia: local control and subsequent clinical events: a Southwest Oncology Group study.

The effectiveness of radiotherapy, 2500 rad over two weeks, in treating leukemic infiltrates of the testicles was studied in 38 boys who met the requirements for tissue conformation of testicular involvement and examination of the bone marrow. The study group was heterogeneous with respect to specific histology and prior therapy. Complete regression of testicular infiltrates was confirmed by repeated biopsy examinations of 32 of 33 patients undergoing the procedure. The single treatment failure occurred in a boy with acute myelogenous leukemia. In all other patients, local disease control following radiotherapy persisted throuthout the remainder of the clinical course. Three of 5 children, however, showed evidence of reseeding of the testicle as a part of the relapse process at post-mortem examination. Statistical analysis of data from the 35 patients with acute lymphocytic leukemia showed the subsequent course of the disease with respect to next relapse, involving either bone marrow (BM) or the central nervous system (CNS), to be dependent on the acute leukemia prognostic group, as determined by age and peripheral white blood cell count (WBC) at the time of diagnosis, and timing of extramedullary disease (EMD). Patients with poor prognosis at the time of diagnosis and EMD afterward had a 3.8 times greater risk of a subsequent BM or CNS relapse than did patients with good or average prognosis and no EMD at any time (P = 0.07). Of the candidate prognostic factors examined with repect to survival, only the number of prior BM relapses was of statistical significance (P = 0.044). Children with two or more prior BM relapses had the worst prognosis for survival from testicular relapse, with a death risk of 3.6 times greater per unit of time than that of children with no or one prior BM relapse. Protective BM and CNS rescue therapy was recommended for those otherwise in complete remission (CR) at the time of testicular relapse. The median times to next relapse for patients receiving both BM and CNS recue therapy and for patients given CNS recue only were 42+ and seven weeks, respectively ( P = 0.09). The type of rescue received did not appear to affect survival time following testicular CR.