The causes of the two types of lymphoma, Hodgkin's lymphoma and non-Hodgkin's lymphoma, are unclear; however, studies in the past 10 years have demonstrated an association between sun exposure and the risk of non-Hodgkin's lymphoma, in particular. Researchers suspect the connection is related to the function of vitamin D in the body.
About Vitamin D-3
Vitamin D-3, also known as cholecalciferol, is synthesized by humans when the skin is exposed to ultraviolet-B rays from the sun. Some foods are fortified with vitamin D-3 or D-2, such as milk and dairy products. The vitamin can also be obtained from fatty fish or supplements. Vitamin D from the sun or diet is metabolized in the liver and further changed into its active form in the kidneys. An article in the "American Journal of Clinical Nutrition" proposed that 5 to 10 minutes of sun exposure on the arms, legs, hands or face two to three times per week should suffice to prevent any vitamin D deficiency. A vitamin D deficiency can cause bone disease and may increase the risk of other diseases and cancers.
About Lymphoma
Lymphoma is a blood cancer that originates in the lymphatic system and may develop in the lymph nodes, spleen, bone marrow or other organs. The Lymphoma Research Foundation estimates that about half a million people in the United States have lymphoma as of 2011. Since the 1970s, incidence rates of NHL have almost doubled. Non-Hodgkin's lymphoma, or NHL, includes many subtypes. Doctors are unsure what causes NHL, but recent research has identified an inverse association between sun exposure and NHL.
Sun Exposure & Non-Hodgkin's Lymphoma
Due to the observation from epidemiological analysis that NHL paralleled cutaneous melanoma, it was hypothesized that sun exposure may cause NHL. The risk of NHL is higher in people with a previous diagnosis of skin cancer, but contrarily, NHL risk had been found to be decreased with an increasing amount of sun exposure. Researchers in Greece took a large number of cases of children with Hodgkin's lymphoma, or HL, NHL and control cases and compared the incidence of lymphomas with sun exposure. They found that the risk for NHL was inversely associated with sun exposure, specifically, for 15 days of sunbathing, the children showed an almost 40 percent reduction in risk for NHL. A study published in the "Journal of the National Cancer Institute" analyzed a group of almost 7,000 patients diagnosed with different types of lymphomas and leukemia and found those patients with a high frequency of sunbathing and sunburns were associated with a 30 to 40 percent reduction in NHL risk. Associations were stronger for the longer amount of time spent in the sun, and they were stronger for B-cell lymphomas. This study, however confirmed that the risk of both NHL and HL doubled with a prior history of skin cancer. Finally, a study published in the "International Journal of Cancer" reported on the analysis of 10 different studies covering over 15,000 patients in the US, Europe and Australia assessing the relationship between NHL and sun exposure. Researchers found a statistically significant association between sun exposure and a reduced risk of NHL for B-cell, but not T-cell lymphomas.
Overall
The evidence showed an association between sun exposure and a reduced risk of the non-Hodgkin's type of lymphoma. Researchers noted that this was recreation sun exposure and also explained the previously established relationship between prior skin cancer and an increased risk of both HL and NHL; therefore, in several studies, sun exposure appears beneficial to reduce NHL risk, but the biological mechanism is unclear ,and people should remain mindful of the risks of skin cancer.
References
- "American Journal of Clinical Nutrition"; Sunlight and Vitamin D for Bone Health and Prevention of Autoimmune Diseases, Cancers, and Cardiovascular Disease; Holick MF; December 2004
- "Journal of Cellular Biochemistry"; Vitamin D: A Millenium Perspective; Holick, MF; February 2003
- Lymphoma Research Foundation; Non-Hodgkin Lymphoma; 2010
- Mayo Clinic; Non-Hodgkin's Lymphoma Causes; Jan 2010
- "Cancer Epidemiology, Biomarkers & Prevention"; Sun Exposure and Non-Hodgkin Lymphoma; Armstrong BK, et al.; March 2007
- "Cancer Causes Control"; Sun Exposure, Birth Weight, and Childhood Lymphomas: A Case Control Study in Greece; Petridou ET, et al.; November 2007
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