A novel study in mice suggests that men are more prone to developing cancer than women because of gender differences in antioxidant levels and the ability to repair DNA damage.
Researchers at Ohio State University found that when exposed to the same degree of damaging ultraviolet (UV) light, the skin of male mice suffered more genetic damage than that of female mice. As a consequence, the male mice developed more squamous cell skin cancers, and these tumors formed faster and grew more aggressively than those that developed in the skin of female mice.
These results may explain why men develop three times as many squamous cell skin cancers as women do, and may also offer a clue as to why men are more prone to cancer development in general, says Kathleen Tober, Ph.D., a research scientist in Ohio State’s Department of Pathology.
“Men get more skin cancer than women and it has classically been thought that the reason for this is lifestyle – men spend more time outside and are less likely to use sun protection,” Tober said. “Our data suggests that while that may be a factor, an even more critical reason for this difference is that female skin may be better able to combat the damaging effects of UV exposure.
“Based on our data, it would be a reasonable hypothesis that one of the underlying mechanisms for this is that men might have less overall antioxidant levels and diminished DNA repair capacity,” she said.
Approximately half of the 2 million-plus cancer cases diagnosed in the U.S. are non-melanoma skin cancers. Squamous cell carcinoma, with 250,000 new cases annually, is the second most common cancer in the country. While it is not always a fatal cancer, it does account for about 2,000 cancer deaths a year.
For years, the project’s lead researcher Tatiana Oberyszyn, Ph.D., assistant professor at Ohio State’s Department of Pathology has studied gender differences in non-melanoma skin cancer. She and her laboratory had initially discovered through controlled experiments that gender and its associated variables accounted for the difference between male and female rates of developing squamous cell carcinomas.
In this study, the researchers discovered that, to their surprise, male mice had less inflammation following exposure to UV light than did female mice, but they had increased oxidative DNA damage possibly due to insufficient levels of proteins that repair DNA damage.
“When equally exposed to sunlight, female skin turns pink and swells up − two classic signs of a sunburn,” Tober said. “Male skin doesn't have as robust of a sunburn response to UV exposure but the genetic damage that male skin incurs is actually greater than female mice.
“Our data tells us that female skin has more antioxidants, compounds that scavenge DNA damaging chemicals, and potentially more mechanisms to repair DNA damage than male skin,” she said. “These gender differences suggest that female skin has a higher capacity for repairing sunlight induced DNA damage than does male skin. Without complete repair of this genetic damage, male skin is more prone to skin cancer than is female skin.”
These findings suggest that gender may need to be considered when it comes to controlling cancer, the researchers say. “Until those strategies are determined and whether you are male or female, it is best to take caution when it comes to sunlight exposure,” Tober said.-American Association for Cancer Research
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