Melanoma is a type of skin cancer that begins in the pigment-producing cells called melanocytes. Unlike other skin cancers, melanoma can grow deeper into the skin and spread to other parts of the body.
Malignant melanoma is particularly concerning because it can spread quickly. The five-year survival rate for melanoma that has spread is only about 15-20%, making it a serious cancer to avoid, even though it is relatively rare. While it has long been believed that sun exposure increases melanoma risk, recent research suggests that the relationship between melanoma and the sun is more complex.
In the United States, from 2009 to 2019, the number of new melanoma cases is estimated to have increased by over 40%, and over the last three decades, the percentage of individuals who develop melanoma has more than doubled (PMID: 38136411).
Something interesting is going on. Although public health messages to avoid the sun, wear sunscreen, and limit UV exposure are intended to reduce the risk of skin cancer, the increases in melanoma cases suggest that the relationship between sun exposure and melanoma is more complex than previously thought. Vitamin D, which is primarily obtained through sun exposure, plays a large role in overall health, cancer prevention, and sufficient levels are associated with a better melanoma prognosis. Incidentally, it is estimated that today around 50 percent of people have a vitamin D deficiency.
Some Things to Consider About Melanoma:
- “Paradoxically, outdoor workers have a decreased risk of melanoma compared with indoor workers, suggesting that chronic sun exposure can have a protective effect.” (PMID: 15005091)
- Melanoma is likely to develop in areas of the body that are not commonly exposed to the sun (between toes, scalp, etc.) and can grow in places with no sun exposure at all.
- Despite widespread sunscreen use, rates of melanoma and other skin cancers continue to rise.
- “The public health messages of the past 50 years to avoid sun exposure and to use chemical sunscreens may have contributed to the rise in melanoma incidence.” (PMID: 27942349)
- Melanoma and other skin cancers are more common in areas with low sun exposure.
Vitamin D and Melanoma
There is substantial scientific evidence suggesting that greater sunlight exposure, which boosts vitamin D synthesis and improves vitamin D status, can affect the risk and outcomes of many deadly cancers, including melanoma.
Vitamin D is an essential fat-soluble vitamin that our bodies primarily synthesize from sunlight. When our skin is exposed to ultraviolet (UV) light from the sun, it triggers the production of vitamin D. This is the most bioavailable form of vitamin D, meaning it is the most easily absorbed and utilized by the body. Vitamin D plays a crucial role in various bodily functions, including supporting immune health and regulating cell growth.
In patients with advanced (stage IV) metastatic melanoma, vitamin D deficiency was linked to significantly worse survival outcomes. Specifically, those who started with low vitamin D levels and experienced only a minimal increase (≤20 ng/mL) in their vitamin D concentration had markedly poorer outcomes compared to patients whose vitamin D levels increased by more than 20 ng/mL. This suggests that improving vitamin D levels may be crucial for better survival rates in individuals with advanced melanoma.
Research has shown that maintaining adequate levels of vitamin D can be especially important for patients with melanoma. Low vitamin D levels have been linked to thicker melanomas at diagnosis and a higher likelihood of cancer recurrence. Insufficient vitamin D may promote the growth of melanoma cells, making it vital to manage vitamin D levels effectively.
This research challenges the conventional medical paradigm that advocates avoiding sun exposure to prevent skin cancer. Adequate sunlight-derived vitamin D levels may actually play a protective role against melanoma progression and recurrence.
When vitamin D levels are sufficient, vitamin D binds to the vitamin D receptor (VDR) in cells. This binding helps inhibit the proliferation of cancer cells and enhance the immune system’s ability to recognize and eliminate them. In individuals with melanoma, elevated levels of vitamin D have been associated with favorable outcomes. Researchers have found that tumors with higher VDR expression often exhibit improved immune responses and less aggressive growth. Conversely, insufficient vitamin D levels are correlated with quicker tumor growth, suggesting that adequate levels may enhance survival rates and improve the body’s capacity to combat cancer.
So, how does vitamin D combat cancer?
- Vitamin D promotes cell differentiation: Vitamin D is one of the most potent hormones for inhibiting cancer cell proliferation and inducing maturation. This is because vitamin D plays a crucial role in cell differentiation, which is the process where cells develop into distinct types with specialized functions. This is important because proper cell differentiation helps maintain normal tissue structure and activity. In melanoma, this process can go awry, leading to uncontrolled cell growth and tumor formation. Vitamin D ensures that cells mature and function correctly, reducing the risk of cancerous transformations. This means that sufficient vitamin D levels regulate cell growth and prevent the unchecked growth that we see in cancer.
- Vitamin D supports immune function: Vitamin D also modulates the immune system by promoting innate immunity and inhibiting adaptive immunity. It binds to receptors on various immune cells, such as macrophages and enhances the innate immune response – the body’s first line of defense against cancer cells and infections. This includes improving the ability of immune cells to identify and destroy malignant cells.
On the other hand, vitamin D suppresses the adaptive immune response, particularly by reducing the activity of T helper 1 (Th1) cells. These cells are involved in specific immune responses and can sometimes contribute to chronic inflammation. In melanoma, this balance is beneficial because it helps prevent excessive inflammation and supports the body’s natural ability to recognize and eliminate cancer cells through the innate immune system.
This topic is complicated because each person has their own biological makeup and risk factors for skin cancer. While it’s extremely important to avoid burns, the internal cancers that are associated with vitamin D deficiency are more aggressive and typically have a worse prognosis. Achieving a balance between safe sun exposure and protection from harmful UV rays is key to maintaining health and connection to nature.
I always advocate for safe sun exposure (no burns) and in some cases vitamin D supplementation is necessary. It’s all about finding a balance with healthy sun exposure and making peace with our environment.