New Orleans--Four-year results of a phase III clinical trial suggest that a single dose of the chemotherapeutic agent carboplatin (Paraplatin) is as safe and effective as adjuvant 3-week-long radiation therapy following orchiectomy of seminomatous testis cancer. More surprising was the observation that there were fewer germ cell cancers in the other testis, British oncologists reported at the American Society of Clinical Oncology annual meeting.
New Orleans-Four-year results of a phase III clinical trial suggest that a single dose of the chemotherapeutic agent carboplatin (Paraplatin) is as safe and effective as adjuvant 3-week-long radiation therapy following orchiectomy of seminomatous testis cancer. More surprising was the observation that there were fewer germ cell cancers in the other testis, British oncologists reported at the American Society of Clinical Oncology annual meeting.
"This observation is the first substantive data which suggest that it may one day be possible to do testis preservation in all men with testis cancers," said R. Timothy Oliver, MD, Sir Maxwell Joseph professor in urology at Barts and The London, Queen Mary's School of Medicine and Dentistry. "This would be valuable in men who have not had children, since these men would retain fertility, as opposed to those who have undergone radiation therapy."
Generally, Dr. Oliver explained, stage I seminoma is treated by surgical removal of the cancerous testis followed by adjuvant radiation therapy. The problem with this approach is that, though it reduces recurrence of testis cancer, there is an increased incidence of other non-testicular cancers 10 to 20 years later.
A total of 1,477 patients with stage I seminoma were randomly assigned to either radiation after surgery (904 patients) or one course of carboplatin (573 patients).
The radiation dose was optionally decided by randomization between 20 Gy/10f and 30 Gy/15f. Of the patients randomized to radiation therapy, 13% had the conventional dogleg field; and 87% had a para-aortic strip, 86 of the latter having scrotal shielding and 668 having no scrotal shielding.
At median 4-year follow-up, relapse-free survival after single-course carboplatin was 98% at 2 years versus 97% in the radiotherapy group. Interestingly, there were only two second germ-cell cancers in the other testis in the 573 patients who received carboplatin compared with 10 second germ-cell cancers in the contralateral testis in the radiation therapy group, all of which were in the patients who received para-aortic strip radiation with no scrotal shielding-a significant difference favoring carboplatin treatment.
Dr. Oliver explained that overall survival was 99.8% in both of the groups, revealing no statistical difference.
Concerning the safety profiles of the two therapeutic modalities, carboplatin patients had a significantly shorter duration of lethargy, nausea, and inability to work. Hematologic toxicities such as leukopenia and thrombocytopenia were both more common in the patients treated with carboplatin than in those on radiation therapy, but the levels of adverse effects were not clinically significant, he said.
"Much longer follow-up is needed to clarify whether the observed reduction of second germ-cell cancers is maintained and its potential for testis conservation," Dr. Oliver said. "Furthermore, we still need to go to 20 years follow-up to establish whether or not there are less second non-germ cell cancers, which we know occurs after radiotherapy."