New York, May 9 (IANS): Men with low levels of the male sex hormone testosterone need not fear that testosterone replacement therapy will increase their risk of prostate cancer, says a study

The researchers found that, as a group, men prescribed testosterone for longer than a year had no overall increase in risk of prostate cancer and, in fact, had their risk of aggressive disease reduced by 50 percent.

The findings are based on an analysis of more than a quarter-million medical records of mostly White men in Sweden.

"Based on our findings, physicians should still be watching for prostate cancer risk factors -- such as being over the age of 40, having African-American ancestry, or having a family history of the disease -- in men taking testosterone therapy, but should not hesitate to prescribe it to appropriate patients for fear of increasing prostate cancer risk," said lead study investigator and Stacy Loeb from NYU Langone Medical Centre in New York.

Specifically, the current study found that 38,570 of the men whose records were examined developed prostate cancer between 2009 and 2012.

Of these men, 284 had prescriptions for testosterone replacement therapy before they were diagnosed with prostate cancer.

Their records were compared with 192,838 men who did not develop prostate cancer, of whom 1,378 had used testosterone therapy.

Researchers noted that while their initial analysis showed an uptick (of 35 percent) in prostate cancer in men shortly after starting therapy, the increase was only in prostate cancers that were at low risk of spreading and was likely a result from more doctor visits and biopsies performed early on.

"Overall, our study suggests that what is best for men's health is to keep testosterone levels balanced and within a normal range," said Loeb, who suggested that men with testosterone levels below 350 nanograms per decilitre and symptoms should seek medical advice about whether they should consider testosterone therapy.

Much of the concern over cancer risk is that, as part of standard therapy for advanced prostate cancer, tumour growth is decreased by drugs that drastically reduce rather than increase male hormones, Loeb pointed out.

Testosterone levels drop naturally by about 1 percent per year in men past their 30s.

"But when used appropriately by men with age-related low testosterone who are otherwise healthy, testosterone replacement has been shown to improve sexual function and mood," Loeb said.

The findings are scheduled to be presented at the annual meeting of the American Urological Association in San Diego, California, US.