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Adjuvant radiotherapy is associated with improved cause-specific survival in stage I testicular seminoma, but at the cost of increased risk of secondary malignancies, according to an analysis of data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database.
Dr. Neelima Vudarla and her coinvestigators reviewed more than 6,700 men who underwent orchiectomy for stage 1 seminoma from 1973 to 2003. A total of 5,265 received adjuvant radiation while 1,499 remained on observation, she said.
Fifteen years after diagnosis, 90% were alive, said Dr. Vudarla, internal medicine resident at Cancer Care Northwest, Spokane, Washington. Multivariate analysis found no difference in overall survival; only radiation therapy was a significant predictor of cause-specific survival (hazard ratio 0.37; P = .0002). "Deaths due to seminoma significantly dropped in the adjuvant radiotherapy group. However, the age at diagnosis and patients' race did not significantly differ with regard to cause-specific survival," Dr. Vudarla said.
The study found 312 patients developed secondary malignancies. Compared with observation, radiotherapy was tied to excess risk for contralateral testicular (68 vs. 9), pancreatic (15 vs. 3), and thyroid (7 vs. 1) malignancies.
"We assume that these patients were treated in the era where huge doses of radiation were used, and we strongly believe the newer radiation techniques, including low-dose and fractionated regimens, might reduce secondary cancers," Dr. Vudarla said.
The study was criticized for not controlling for increasingly sensitive imaging technology that has altered tumor staging. Discussant, Dr. Mary K. Gospodarowicz of Princess Margaret Hospital, Toronto, said: "There was legitimate criticism in that the follow-up period was shorter in the observation group, and there was case ascertainment."
Vudarla N. et al. Survival and secondary malignancy rates for adjuvant radiation therapy versus observation in stage I testicular seminoma: A Surveillance, Epidemiology, and End Results (SEER) analysis. Abstract 5020.
Commentary |
Treatment for stage I seminoma has evolved, perhaps more dramatically than for any other neoplasm. While the volume irradiated and total dose have decreased dramatically, some institutions have used serial blood tests and episodic imaging to detect recurrences early. With this approach, about 80% of men will require no further treatment after radical orchiectomy and will not be at risk for the long-term toxicities. This population-based survey does not take into account improved imaging at diagnosis and the development of highly effective chemotherapy. It is imprudent to conclude that adjuvant radiotherapy improves cause-specific survival in stage I seminoma. — W. Robert Lee, M.D., and Judd W. Moul, M.D.
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