Post-chemotherapy surgery in advanced non-seminomatous germ-cell testicular tumours: the significance of histology with particular reference to differentiated (mature) teratoma.

Of a total of 307 patients treated with chemotherapy for advanced non-seminomatous germ-cell testicular tumours between 1976 and 1983, 73 (23.8%) had masses excised after treatment. Resected tissue showed residual malignancy in 16 (22%), fibrosis and necrosis in 25 (34%) and differentiated (mature teratoma) in 32 (44%). Of the 16 patients with tumour only 7 (44%) are alive and disease-free compared with 21/25 (84%) and 27/32 (84%) for fibrosis/necrosis and differentiated teratoma respectively. In addition to histological evidence of residual tumour, elevated serum markers at the time of surgery and/or incomplete excision of residual masses were adverse prognostic features. Of 12 patients with differentiated teratoma or fibrosis who had incomplete resections or densely adherent masses excised with difficulty, 7 subsequently relapsed. The majority of differentiated teratoma patients (75%) had evidence of differentiation in their primary tumours; 88% showed cystic change in metastases and almost one-third showed an increase in the size of metastases during chemotherapy. The data suggest that post-chemotherapy surgery may have a therapeutic as well as a diagnostic role and that complete excision of residual disease should be attempted even if resection at one site has shown either fibrosis or differentiated teratoma. The significance of these findings in relation to treatment induced differentiation is discussed.