MelanomaCancer of the skin (including melanoma and basal and squamous cell skin cancers) is by far the most common of all types of cancer. According to one estimate, about 3.5 million basal and squamous cell skin cancers are diagnosed each year (occurring in about 2.2 million Americans, as some people have more than one). About eight out of 10 of these are basal cell cancers. Squamous cell cancers occur less often. However, I wanted to finish this series with a look at melanoma, because, according to the American Cancer Society, though it's the least common of all diagnosed skin cancers at approximately 4%, it accounts for about 77% of cancer deaths.
To put it in a most startling way—one person dies of melanoma every hour.
Melanoma and UVA
Our previous blog posts discussed the role played by UVB light in inducing squamous and basal cell carcinomas via direct DNA damage. We’ve studied these mechanisms for years, but only recently have we established the link between UVA light and melanoma induction. This isn’t too surprising, since it’s difficult to distinguish UVA from UVB damage. Up until a few years ago, we assumed the UVB light was the culprit involved in all skin cancers, including melanoma.
Some clues have put us on a different track. For one thing, people who frequented tanning beds, which use UVA wavelengths of light to create tans, were found to develop high rates of melanoma. In fact indoor ultraviolet (UV) tanners are 74% more likely to develop melanoma than those who have never tanned indoors.
Another clue is in the fingerprints left by UVB. Non-melanoma-type skin cancers produce 'signature mutations.' Pyrimidine dimers and 6-4 photoproducts, which commonly occur in squamous and basal cell carcinomas, are not seen in melanomas.
And finally—in vivo studies. One using Xiphophorus fish and another based on human epidemiological evidence* support the hypothesis that melanoma is caused by UVA wavelengths (320 to 400 nm), extending into the visible light spectrum at 405 nm.
Melanoma and Inflammation
The ability of UV radiation to cause tumor-initiating DNA mutations in melanocytes is now firmly established. Also crucial is inflammation’s contribution (the root cause of so many undesirable skin conditions—including wrinkles) is also crucial, and should not be overlooked in our attempts to understand melanoma. The main cause of death in people with melanoma is the spread of tumors. Studies now show that UV exposure to melanoma causes an inflammatory response that promotes the formation of distant metastasis.
What Can We Do?
Now that we know a link exists between UVA and melanoma, the prevalence of UVA is that much more of a concern. One-thousand times more prevalent than UVB, they penetrate glass and clouds and are present from sunup to sundown.
Safeguard yourself by making these few preventative steps part of your daily routine.UVA protection is more important than UVB protection. This may be still considered controversial, but I believe the ideal sunscreen has a high UVA rating and an SPF rating not exceeding 30, which indicates levels of UVB protection. Sunscreens with high UVB and low UVA protection give you a false sense of security, leading you to believe that because you're not burning you are not incurring sun damage. It’s probably better to think of sunburn as nature’s alarm system, which you turn off with high SPF sunscreens at your peril. Use an SPF 30, and if you are turning pink it’s time to get out of the sun!
Always remember: For those of you courting a 'healthy looking' tan, UVA rays may give you that coveted bronze glow, but they'll also expose you to:
- the effects of aging by cross-linking collagen and elastin;
- the destruction of Langerhans cells and immune function;
- free radical generation; and
- carcinogenic and melanogenic effects.
Seek out products with a good UVA rating or better yet, a high zinc oxide content. The UVA-rated chemical sunscreens can be problematic. Avobenzone, which protects in the UVA range up to 400 nm by means of chemical absorption is very unstable and starts to degrade in the sun in as little as 30 minutes. It is commonly stabilized with octocrylene, but recent studies indicate that octocrylene is not only on the list of free-radical-generating chemicals we should avoid, but is also a strong allergen that can lead to contact dermatitis.
If you want to stay away from chemicals, use sunscreens containing high amounts of zinc oxide for protection up to 400 nm. And because zinc oxide is photostable, you won’t run the risk of exposing yourself to free-radical damage or allergic reactions resulting from chemical breakdown products. Another plus—zinc oxide has anti-inflammatory effects.
Modulate inflammation. News about aspirin lowering the melanoma risk for post-menopausal women has everyone talking. Taking an aspirin a day certainly can’t hurt. (If you are aspirin-sensitive, choose the low-dose buffered varieties that won’t burn your stomach.) Other anti-inflammatories like resveratrol and turmeric can also be included on your list of anti-inflammatories worth investigating.
*(Moan, J., Dahlback, A., & Setlow, R.B. (1999), Epidemiological support for a hypothesis for melanoma induction indicating a role for UVA radiation. Photochem Photobiol 70, 243-247.)
Sun Protection Tips
The two most important things to consider when protecting against deadly skin cancers are:
- Protect from UVA rays with zinc oxide. Remember that high SPF does not protect you from UVA rays, and zinc oxide protects better than chemical sunscreens containing combo agents like avobenzone/octocrylene.
- Modulate inflammation with a combination of supplements taken internally as well appliedy externally.
Ingestion: Anti-inflammatories to be taken internally.
- Low-dose aspirin
Topical: Anti-inflammatories to be applied externally.
- Zinc oxide sunscreen: Apply daily.
- Many oils feature anti-inflammatory, antioxidant and UV- protection benefits. We recommend:
- Extra-virgin olive oil contains a natural anti-inflammatory agen
- Algae and kiwi seed oils are high in anti-inflammatory omega-3 EFAs.
- Cranberry seed and blackberry seed oils are powerful antioxidant
- Krill oil is a carotenoid-rich oil that contains astaxanthin.
- Red raspberry oil: Though reports** of its UV protective capacities at SPFs of between 28 and 50 have yet to be verified, I believe it does contain many important phytochemicals with demonstrated anti-cancer effects: ellagic acid, quercetin and anthocyanins. **(Oomah et al, 2000)
- Broccoli seed oil: The University of Arizona reported that preliminary research on glucoraphanin showed that topical broccoli-based ointments may inhibit the growth of cancer-causing proteins, while activating chemoprotective genes.
- Sodium salicylate, the salt of salicylic acid (aspirin) has proven anti-inflammatory as well as UV protective properties (see blog post #2 in the series). Use a sunscreen that contains it.
Epsom salts. Magnesium sulfate has mild anti-inflammatory properties and can be absorbed through the skin. Baths in Epsom salts are good for many skin conditions, including sunburn.