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THURSDAY, May 15 (HealthDay News) -- Genetic differences may explain why white men have a higher prostate cancer risk than Hispanic men, information which may help doctors identify men who are more likely to develop the disease, U.S. researchers say.

They collected blood samples from 932 white men and 414 Hispanic men from south Texas and looked for mutations from the nuclear vitamin D receptor (CDX2 and FokI), which modulates the actions of vitamin D, and from 5-reductase type II (V89L & A49T), which converts testosterone to dihydrotestosterone, a more potent form of the male hormone.

Among non-Hispanic white men with V89L, FokI was associated with a more than a 50 percent increased risk of prostate cancer. This effect was not seen in Hispanic men. Among Hispanic white men, a combination of CDX2 and V89L was associated with a more than threefold increased risk of prostate cancer. This link was not seen in white men.

The findings, published in the May 15 issue of Clinical Cancer Research, provide new information about genetic risks and racial differences, but need to be confirmed in larger studies.

"Prostate cancer is not likely caused by a few genes, but by multiple genes from different pathways. This study illustrates the importance of examining multiple genes to understand genetic risks for prostate cancer and differences seen by ethnicity," study author Kathleen Torkko, an instructor in the department of pathology at the University of Colorado, Denver, said in a prepared statement.

"Going forward, we need not only a better understanding of genetics but a better understanding of race and ethnicity. Studying disease by race is a complex issue, and the public needs to understand that we are trying to raise biological, rather than social, questions," Torkko said.

She said the goal of this research is to find ways to improve management and treatment of prostate cancer. Currently, the most common method for assessing prostate cancer risk is the prostate specific antigen (PSA) test. But the test can identify tumors that may not be a threat, while missing other tumors.

"Men typically have this test after they turn 50 years old, and it can spot a tumor that may not cause a problem in a man's lifetime if left untreated. It could be more likely that a man will die from heart disease or some other ailment before his prostate cancer would kill him," Torkko said.

"At this point, it is not possible to accurately tell which tumors will be the more aggressive ones with our current screening tests. This means that we may be screening and treating some men unnecessarily," she noted.

More information

The National Cancer Institute has more about prostate cancer screening.

MONDAY, July 7 (HealthDay News) -- Among couples with fertility problems, those in which the man is over age 35 have lower pregnancy rates and increased chances of miscarriage, a new study shows.

To come to this conclusion, French researchers looked at more than 12,000 couples who went to a fertility clinic in France.

In most of the cases, the couples were being treated due to the man's infertility. The couples underwent a total of 21,239 intrauterine inseminations (IUIs).

The researchers found that women over age 35 had a pregnancy rate of 8.9 percent, compared to 14.5 percent in younger women.

"But we also found that the age of the father was important in pregnancy rates -- men over 35 had a negative effect. And, perhaps more surprisingly, miscarriage rates increased where the father was over 35," study author Dr. Stephanie Belloc, of the Eylau Center for Assisted Reproduction in Paris, said in a prepared statement.

This is the first study to document such a strong paternal effect on reproductive outcomes. The findings were presented Monday at the European Society of Human Reproduction and Embryology annual conference, in Barcelona.

"How DNA damage in older men translates into clinical practice has not been shown up to now. Our research proves for the first time that there is a strong paternal age-related effect on IUI outcomes, and this information should be considered by both doctors and patients in assisted reproduction outcomes," Belloc said.

"We believe that the use of IVF or ICSI should be suggested to infertile patients where either party is over 35 years of age," she added.

More information

The American Society for Reproductive Medicine has more about infertility  .