Esha Mukherjee, Amity University Noida
Colorectal cancer is a cancer that begins in the colon or the rectum. According to a study published in the journal BMC Public Health, insufficient exposure to Ultraviolet-B (UVB) light from the sun may be associated with an increased risk of colorectal cancer, particularly in older age groups. Vitamin D has been found as a possible preventive factor against colorectal cancer development (CRC). Because chronic vitamin D insufficiency leads to long-term molecular alterations that raise cancer risk, we anticipate detecting a larger link between UVB exposure and CRC crude rates as people get older. The DINOMIT (disjunction, initiation, natural selection, overgrowth, metastasis, involution, and transition) model proposes that vitamin D deficiency leads to multiple stages of cancer development and a latency period. The goal of this research is to look at this age-dependent inverse association on a worldwide scale.
About the study:
A series of linear and polynomial regression analyses were performed between country-specific UVB values corrected for cloud cover and crude CRC incidence rates for various age groups in this ecological investigation. The link between crude incidence rates of colorectal cancer and UVB estimation was investigated using multiple linear regression after controlling for urbanisation, skin pigmentation, smoking, animal intake, per capita GDP, and life expectancy. Following the statistical analysis, choropleth maps were created as a means of geospatial visualisation.
Affected UVB exposure, according to scientists, may lower vitamin D levels. Vitamin D insufficiency has been linked to an increased risk of colorectal cancer in the past. According to the authors, future research might look directly at the possible benefits of addressing vitamin D deficiency on colorectal cancer, especially in older age groups.
The researchers used UVB estimates from NASA’s EOS Aura spacecraft in April 2017 and data from the Global Cancer (GLOBOCAN) database on colorectal cancer rates in 2018 for 186 nations. They also gathered data from previous literature and databases for 148 nations on skin pigmentation, life expectancy, smoking, stratospheric ozone (a naturally occurring gas that filters the sun’s radiation), and other factors that may influence health and UVB exposure. Norway, Denmark, and Canada had lower UVB levels, while the United Arab Emirates, Sudan, Nigeria, and India had greater UVB levels.
Results
At the country level, the inverse link between UVB exposure and CRC crude rates were great in older age groups. For all age groups, quadratic curve fitting favoured, and these models were statistically significant. After adjusting for confounders, the inverse relationship between crude CRC incidence rates and UVB exposure was statistically significant for age groups over 45 years.
Conclusion
In worldwide analysis, the age-dependent inverse correlation between UVB exposure and colorectal cancer incidence had a larger effect size among older age groups. The impact of chronic vitamin D insufficiency on colorectal cancer aetiology will aid for population-wide vitamin D deficiency screening programmes. More research is needed to determine whether suitable public health initiatives, such as targeted supplementation and dietary fortification, are required.
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References:
- Purushothaman, V.L., Cuomo, R.E., Garland, C.F. et al. Could age increase the strength of inverse association between ultraviolet B exposure and colorectal cancer?. BMC Public Health 21, 1238 (2021). https://doi.org/10.1186/s12889-021-11089-w
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