How UVB Light Exposure Affect Colorectal Cancer Risk?

The association between inadequate exposure to ultraviolet-B (UVB) light from the sun and an increased risk of colorectal cancer helps understand the role of vitamin D deficiency.

Inadequate exposure to ultraviolet-B (UVB) light from the sun increases the colorectal cancer risk as people age, according to a new study published in the journal BMC Public Health.

University of California San Diego School of Medicine researchers investigated global associations between levels of UVB light and rates of colorectal cancer across several age groups in 186 countries.

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‘Colorectal cancer risk increases with the lower UVB light exposure in older age.’

Though lower UVB exposure is correlated with higher rates of colorectal cancer across all age groups, it remained significant for people aged 45 and older even after considering other factors, such as skin pigmentation, life expectancy and smoking.

"Differences in UVB light accounted for a large amount of the variation we saw in colorectal cancer rates, especially for people over age 45. Although this is still preliminary evidence, it may be that older individuals, in particular, may reduce their risk of colorectal cancer by correcting deficiencies in vitamin D," said Raphael Cuomo, PhD, assistant professor of anaesthesiology at UC San Diego School of Medicine..

Eventhough vitamin D deficiency has previously been associated with an increased risk of colorectal cancer, this study suggests future research on potential benefits of correcting vitamin D deficiencies to reduce colorectal cancer risk in older age groups.

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There are more than 1.5 million colorectal cancer survivors living in the United States even after improving prevention, early detection and treatment of colorectal cancer. This makes it the second deadliest cancer among U.S people.

The researchers used UVB estimates obtained by the NASA EOS Aura spacecraft in April 2017 and data on colorectal cancer rates in 2018 for 186 countries from the World Health Organization's Global Cancer (GLOBOCAN) database.

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They also collected data from 148 countries on skin pigmentation, life expectancy, smoking, stratospheric ozone (a naturally occurring gas that filters solar radiation) and other factors that might influence health and UVB exposure.

Countries with lower UVB included Norway, Denmark and Canada; countries with higher UVB included United Arab Emirates, Sudan, Nigeria and India.

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The other factors affecting UVB exposure and vitamin D levels, such as vitamin D supplements, clothing and air pollution, are not included in the study.

The observational nature of the study also does not allow for conclusions about cause and effect and more work is needed to fully understand the relationship between UVB, vitamin D and colorectal cancer.

Source-Medindia