New research suggests less risk from UVB exposure
new study conducted in the US that suggests exposure to UVB rays
from the sun might not be as dangerous as scientists first thought.
Although the over-ridding consensus is that individuals should still always do their best to protect themselves from sun exposure, a study carried out at the University of Texas Anderson Cancer Center in Houston, suggests that UVB exposure is more likely to lead to non-malignant forms of cancer, rather than the more deadly cutaneous malignant melanoma.
However, the team, which was headed up by Dr. Quingyi Wei, added that exposure to UVA rays leads to premature skin aging and DNA damage and that UVB rays are still partly associated with the development of melanoma.
The study, which included 469 patients with either melanoma or non-melanoma cancers, involved in vitro studies of the relationship between UVB exposure and chromosomal damage in the patients skin cells.
"Although we have refined the common wisdom that excess sun exposure is always associated with increased risk of skin cancer, the take-home message for the public is still the same - limit sun exposure and use a sunscreen that blocks both UVA and UVB rays," Dr. Wei said.
The results found that that the number of chromatid breaks per cell caused by UVB exposure was significantly higher for patients with non-malignant cancers, when compared to the controls. Likewise, the same test on melanoma patients revealed that there was no significant difference in chromatid break.
The scientists also found that chromatic breaking, or mutagen sensitivity, was significantly higher for those patients with a history of blistering caused by sunburn, which in turn led to a higher risk of basal cell carcinoma.
Hair color, skin type and family history of skin cancer was associated with squamous cell carcinoma, but the results also showed a similar relationship between mutagen sensitivity, risk factors and melanoma.
From the results, the authors of the report were able to conclude that UVB-induced mutagen sensitivity reflects a natural sensitivity to non-malignant skin cancer, but not cutaneous malignant melanoma.
The findings, which were reported in the Journal of the National Cancer Institute, could influence the development of future sunscreen products, which have increasingly tried to strike a correct balance to provide adequate protection for both UVA and UVB rays.