The effect of radiotherapy treatment changes on sites of relapse in stage I testicular seminoma

AIM: To evaluate relapse patterns in stage I testicular seminoma related to changes in radiotherapy practice. METHOD: Four hundred and six patients with stage I testicular seminoma were treated with adjuvant radiotherapy following orchidectomy: 338 patients re ceived para-aortic radiotherapy only and 68 patients with added risk factor s had radiotherapy extended to include the pelvis. Computed tomograms of re lapsed patients were reviewed and sites of relapse were documented with cor relation to the radiotherapy field. RESULTS: Thirteen relapses were identified; 10 occurring in the para-aortic radiotherapy group (3.0% relapse rate) and three in the extended radiother apy field group (4.4% relapse rate). Sites of relapse were; five pelvis, th ree mediastinum, one lung, one scapula, one scrotum, while one patient had multiple relapse sites including the pelvis and one had a tumour marker rel apse with no site identified, All the pelvic relapses occurred in the para- aortic radiotherapy group. CONCLUSION: Pelvic relapse only occurred when radiotherapy had been confine d to the paraaortic region. Since para-aortic radiotherapy achieves equival ent outcome to wider field radiotherapy with reduced toxicity, it is likely to become standard practice in stage I seminoma and pelvic relapses will t herefore increase in frequency. It is therefore important to include pelvic imaging when relapse is suspected. Taylor, M. B. et al. (2001). Clinical R adiology 56, 116-119. (C) 2001 The Royal College of Radiologists.