FRIDAY, Oct. 31, 2008 (HealthDay News) -- Pregnant women who experience severe high blood pressure may find that their risky condition ultimately helps protect their sons from testicular cancer, a new study suggests.
The reasons for the possible association remain unclear. However, the study authors theorize one possible chain-reaction explanation, in which the malfunctioning of a pregnant woman's placenta causes blood pressure to rise and/or blood vessels to narrow. This, in turn, leads to a drop in estrogen production, which could lower the risk of testicular cancer for a mother's son.
A similar drop in another pregnancy-related hormone known as human chorionic gonadotropin may also play a role, the researchers said.
But whatever the potential link, the researchers stressed that mothers should not be concerned about a reverse association. Women who do not experience high blood pressure while pregnant -- also known as preeclampsia -- will not inadvertently place their sons at increased risk for testicular cancer.
"High blood pressure by itself is not thought to protect against testicular cancer," said study author Dr. Andreas Pettersson, with the clinical epidemiology unit at the Karolinska University Hospital's department of medicine, in Stockholm, Sweden. "Rather, we speculate that high blood pressure is related to other changes during pregnancy that lower the risk of testicular cancer among the sons."
Pettersson and his Swedish and Italian colleagues reported their findings in the Nov. 1 issue of Cancer Research.
According to the U.S. National Cancer Institute, there will be an estimated 8,100 cases of testicular cancer diagnosed in the United States in 2008, and about 380 men will die of the disease.
For the new study, the researchers examined 293 cases of testicular cancer that were gathered by the Swedish Cancer Register. After focusing on data concerning the patients' mothers and their medical histories while pregnant, the researchers evaluated similar records for 861 Swedish men without testicular cancer.
The researchers found that sons of mothers who had experienced severe high blood pressure while pregnant appeared to have more than a 70 percent reduction in risk for developing testicular cancer. Sons of mothers who experienced mild high blood pressure were found to have an apparent 62 percent increase in risk.
Pettersson acknowledged that the findings will probably "have few clinical or everyday implications." But, he added, they may ultimately help scientists get at the underlying factors that contribute to testicular cancer.
Dr. Marc Goldstein, surgeon-in-chief of male reproductive medicine and surgery at New York-Presbyterian Hospital, Weill Cornell Medical Center, in New York City, said such a goal was worthwhile, given the "steady rise in the incidence of testicular cancer over the last few decades, most prominently in Scandinavian countries, but also here in the U.S. as well."
Goldstein said one of the main theories seeking to explain the rise is exposure to estrogen-like substances such as phthalates, which are chemicals increasingly found in plastics -- such as food wrapping, IV tubing and fluid containers. Many hairsprays, perfumes, lubricants, and wood finishers also contain phthalates, he said.
"And the ubiquity of the compound has been already shown to be associated with an increase in estrogen-like substances in pregnant women," he said. "So it's been suspected that it's also one of the factors in the increase of testicular cancer, because its presence may lower the testosterone environment of male fetuses, and this has been associated with an increase in testicular cancer risk."
To learn more about testicular cancer, visit the U.S. National Cancer Institute.