The radioactive seeds used in brachytherapy (internal radiotherapy) for early prostate cancer may damage the DNA in a man's sperm, a small study finds.
The damage seems to be enough to make a man infertile, the researchers say.
Studies have found that brachytherapy is less likely to cause erectile dysfunction than either traditional external radiation or surgical removal of the prostate gland. On the other hand, studies have suggested that men who undergo brachytherapy often become infertile. But there are case reports of patients who have gone on to be fathers - planned or not.
Dr Neil Fleshner, the senior researcher on the new study, commented in an interview that "more and more prostate cancers are being diagnosed in younger men, and there are more and more older men who still want to have children".
Dr Fleshner, who heads urology at the University Health Network in Toronto, Canada, and his colleagues studied semen samples from five men who'd undergone brachytherapy at least one year earlier, all of whom were younger than 55.
They compared the samples with published data on healthy, fertile men and with information on more than 7 600 infertile men who were part of a large database.
Overall, 46% of sperm from the brachytherapy patients had DNA fragmentation, which in great enough proportion would render a man infertile. By comparison, 13% of sperm from fertile men and 20% from infertile men had such damage.
All five brachytherapy patients had an abnormally high amount of genetically damaged sperm -- "indicating likely infertility in all", Dr Fleshner's team reported online in the Journal of Urology.
"If a man is going for brachytherapy, then sperm-banking may be a good idea," Dr Fleshner said. Because brachytherapy is used for early-stage prostate cancer, some men who are candidates for it may also be able to delay having any treatment at all and opt for active surveillance instead.
One study found that more than 120 000 American men diagnosed with prostate cancer every year are ideal candidates for active surveillance. In reality, though, the majority of those men end up having surgery, radiation or other treatment instead.
(Amy Norton, Reuters Health, January 2012)