Sun Exposure May Help Prevent Cancer

Author: Kara Travis

Advisors: Professor Vandyke and Dr. Weaver

• During the 19th and early 20th centuries the sun was avoided by the upper class

• In the late 1900’s sun exposure became very popular

• Several years later it was discovered that sun exposure caused skin cancer

Background on Sun Exposure

• New research has established that people who are following current sun avoidance guidelines are becoming vitamin D deficient.

• Vitamin D deficiency increases risks for several types of cancers

• The cancers caused by vitamin D deficiency are far more deadly, than skin cancers

Current Thoughts on Sun Exposure

Scientific Studies

• 2002 study by the American Cancer Society

• 2004 study about prostate cancer

• 2004 study on non-Hodgkin lymphoma

• Numerous additional studies on lung, breast, and colon cancer

Grant WB. An estimate of premature cancer mortality in the U.S. due to inadequate doses of solar ultraviolet-B. Cancer 2002; 94:1867-75.

• Estimated the number and types of cancers affected by sun exposure and the number of premature deaths due to a lack of UV exposure

• Analyzed cancer mortality rates and UV-B exposure in geographic locations

• Results: 13 types of cancers are statistically inversely correlated with sun exposure and an estimated 21,700 premature deaths occur annually

John EG, Dreon DM, Koo J, Schwartz GM. Residential sunlight exposure is associated with a decreased risk of prostate cancer. J of St Biochem and Mol

Bio. 2004; 89-90 (1-5):549-52.

• Supported the hypothesis that sun exposure reduces the risk of prostate cancer

• Conducted detailed surveys that adjusted for age, family history, and dietary intake

• Concluded that the risk of prostate cancer was reduced by as much as 50% for men who resided in the southernmost states

Hughes AM, Armstrong BK, Vajdic CM, Turner J, Grulich AE, Fritschi L, et al. Sun exposure may protect against non-Hodgkin lymphoma: a case-control

study. Int J Cancer. 2004; 112:865-71.

• Discovered that sun exposure provided protection against non-Hodgkin's lymphoma

• Also a group comparison survey

• This association was strongest in women and children

The Role of Vitamin D

• 2 ways to get vitamin D (skin synthesis and diet)

• Sunlight is the major source of vitamin D for most people

• Vitamin D supplements are not as effective

The Role of Vitamin D

• Deficiency has been reported in 36% of healthy young adults and 57% of hospital inpatients

• Vitamin D deficiency is also linked to rickets in children and osteoporosis and secondary hyperparathyroidism in adults

• Vitamin D has been proven to have anti-tumor activity

• Possible link to inhibition of angiogenesis in tumors

• Current phase I and II clinical trials for use of vitamin D in various cancer treatments

How Does Vitamin D Decrease Cancer Risk?

The Bottom Line

• Most individuals are not receiving enough vitamin D

• Sun exposure is the easiest and most efficient way to produce enough vitamin D

• Sun exposure still causes skin cancers

• Skin cancer has a low mortality rate

Is the sun exposure worth the risk of skin cancer?

Site of Cancer Est. New Cases Est. Deaths % Mortality

Lung and Bronchus

172.570 163,510 94.7%

Colorectal 149,280 56,910 38.1%

Breast 212,930 40,870 19.2%

Prostate 232,090 30,350 13.1%

NHL 56,390 19,200 34.0%

Melanoma 59,580 7,770 13.0%

What do I tell my patients?

• 5-10 minutes of sun exposure daily on hands and face

• Still use sunscreen after the 5-10 minutes• Avoid sunburns, especially in childhood • Pay close attention to specific groups of

patients (elderly, African Americans, certain religious backgrounds)

Conclusion

• It is time for clinicians to rethink their harsh recommendations on sun exposure

• Watch for more published articles and research studies in the near future

Questions?

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