Interaction of body mass index or waist-to-hip ratio and sun exposure associated with nonmelanoma skin cancer: A prospective study from the Women's Health Initiative

Body mass index and the risk of basal cell carcinoma: evidence from Mendelian randomization analysis

Objective

We aim to test whether body mass index (BMI) is causally associated with the risk of basal cell carcinoma (BCC) using Mendelian randomization (MR) analysis.

Methods

Single-nucleotide polymorphisms (SNPs) associated with four BMI-related traits were screened via a genome-wide association study (GWAS) with 681,275, 336,107, 454,884, and 461,460 European-descent individuals, respectively. Summary-level data for BCC (17,416 cases and 375,455 controls) were extracted from UK Biobank. An inverse variance weighted (IVW) method was employed as the primary MR analysis. Sensitivity analyses were conducted via MR-Egger regression, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test. The assumption that exposure causes outcome was verified using the MR Steiger test. Meta-analysis was also used to estimate the average genetically predicted effect of BMI on BCC.

Results

Two-sample MR analysis showed inverse associations between genetically predicted BMI and BCC risk. Moreover, when exposure and outcome were switched to see if reverse causation was possible, there was no evidence of a cause-and-effect relationship from BCC to BMI. Finally, the meta-analysis also showed a strong negative causal relationship between BMI and BCC.

Conclusion

Genetical predicted higher BMI were associated with lower BCC risk. Further research is required to comprehend the mechanisms underlying this putative causative association.

Exposed Body Surface Area-A Determinate for UV Radiant Energy in Human UV Exposure Studies

Solar ultraviolet (UV) exposure of people and related health risk is mainly examined by estimating the received UV radiant exposure. However, for several effects such as DNA damage, vitamin D photosynthesis or the probability of developing skin cancer, UV radiant energy is important and with that the size of exposed skin area. There is also a complex interaction between body shape and behavior like sun exposure habits, so that careful analysis is necessary when estimating health effects from UV exposure. In this paper, knowledge on body shape and methods of calculating the total body surface area (BSA) are summarized. BSA depends mainly on the height and weight of a person as well as on gender, ethnicity and body shape. BSA and body shape differ significantly between different populations and both change during life. This paper proposes formulas for BSA that consider height, weight, gender, ethnicity and body shape. As the exposed BSA depends on clothing, finally an approach is presented which aims to calculate the size of body parts released by real garments. In summary, this paper will enable future researchers to quantify the exposed BSA by best matching their study population and consequently investigate risks caused by solar UV exposure.

Ultraviolet Radiation and Basal Cell Carcinoma: An Environmental Perspective

Ultraviolet radiation (UVR) is a known carcinogen participated for the development of skin cancers. Solar UVR exposure, particularly ultraviolet B (UVB), is the mostly significant environmental risk factor for the occurrence and progress of basal cell carcinoma(BCC). Both cumulative and intermittent high-grade UVR exposure could promote the uncontrolled replication of skin cells. There are also exsiting other contributing environmental factors that combine with the UVR exposure to promote the development of BCC. DNA damage in formation of skin cancers is considered to be a result of UVR toxicity. It is UVR that could activate a series of oncogenes simultaneously inactivating tumor suppressor genes and aberrant proliferation and survival of keratinocytes that repair these damages. Furthermore, mounting evidence demonstrates that inflammatory responses of immune cells in the tumor microenvironment plays crucial role in the skin tumorigenesis as well. In this chapter, we will follow the function of UVR in the onset and development of BCC. We describe the factors that influence BCC induced by UVR, and also review the recent advances of pathogenesis of BCC induced by UVR from the genetic and inflammatory aspects.

Obesity in midlife: lifestyle and dietary strategies

As the rate of obesity increases globally, so does the incidence of other non-communicable diseases such as diabetes, cardiovascular disease, cancer, osteoporosis, osteoarthritis, and dementia, which have been referred to as 'adiposity-based chronic disease'. With timely lifestyle modification such as behavioral changes, implementation of a healthy diet, and proper physical activity, many of these diseases can be prevented. Weight gain is one of the major health concerns of midlife. Midlife body changes are the result of aging, menopause, and other influences unique to menopausal women which interfere with adoption of a healthy lifestyle. Reduced metabolism levels lead to low energy levels, which discourage physical activity. In addition, with the onset of bone loss, menopausal women begin to lose muscle mass and gain more fat, resulting in osteopenic sarco-obesity. Adoption of a healthy lifestyle is a first-line option in the treatment for these midlife changes. Lifestyle medicine offers a broad set of network-based interventions, which need to be brought to the forefront in preventing and managing obesity at all stages. This review article focuses on evidence-based lifestyle changes and their benefits for reducing morbidity and mortality related to obesity and its complications prevalent at midlife and beyond.