"The risk of EBRT-associated second primary malignancy persists for years after the initial seminoma diagnosis, and patients should be informed about these long-term risks," advise the authors of the report in BJU International, online August 22.
They explain that adjuvant EBRT after orchiectomy has been the standard of care until recently for stage I seminoma, even though it confers long-term risks of second primary cancers and only 20% of patients will relapse without it.
To quantify the risk of second malignancies in this setting, Dr. Dan Lewinshtein, with the Virginia Mason Medical Center in Seattle, Washington, and colleagues used the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database.
Among 5,994 men diagnosed with clinical stage I seminoma between 1973 and 2000, most (79%) received EBRT as part of their initial treatment.
Compared to the general population, the incidence of all solid and blood-based malignancies, excluding secondary testicular cancer, was 19% higher in men exposed to EBRT (observed-to-expected [O/E] ratio, 1.19), the team found. On the other hand, there was a nonsignificant decrease in cancer incidence among those not exposed to EBRT (O/E, 0.81).
Specifically, the exposed group was at significantly higher risk for thyroid cancer (O/E, 2.32), pancreatic cancer (O/E, 2.38), nonbladder urothelial malignancies (O/E, 4.27), bladder cancer (O/E, 1.47), and all hematological malignancies (O/E, 1.44), according to the report.
Moreover, patients exposed to EBRT had a significant and persistently elevated risk of second malignancies extending beyond 15 years from the time of the initial seminoma diagnosis, Dr. Lewinshtein and colleagues report.
In discussing the results, they point out that EBRT continues to be used in the U.S. for seminoma despite numerous reports that active surveillance affords equivalent survival.
"Given the long-term toxicity profile of EBRT, surveillance should be strongly considered in men with clinical stage I seminoma," the authors suggest, "and men who have already received adjuvant EBRT should be counseled about the risks of secondary primary malignancies."
BJU Int 2011.
Last Updated: 2011-09-07 17:36:11 -0400 (Reuters Health)
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