Sun & Tanning May Decrease Melanoma Risk
From Daily Dose (4/13) William Campbell Douglass II, M.D.The Real Reason Melanoma Rates Are Climbing
If you want to protect yourself from deadly skin cancer, step out into the
light. SUNLIGHT, that is - because our nearest star is the best defense you have
against melanoma. I know that after decades of sun-hating propaganda that
sounds positively crazy - maybe even suicidal - but new research confirms
everything I've been telling you about this disease. And it confirms what
you've seen yourself - because if you're over the age of 50, you probably remember playing outside
everyday without ever hearing the words "sunscreen" or "melanoma." The disease
wasn't just rare. Among kids, it was unheard of.
Then, starting in the early 1970s, melanoma rates among kids began climbing at a
rate of 2 percent a year. And today, the disease is responsible for 3 percent
of all pediatric cancers. Looks like it's not so rare anymore. The mainstream
is scratching its collective head over the new numbers in Pediatrics. They're
blaming things like tanning beds and beach vacations, and dishing out the same
tired advice about making sure everyone wears sunscreen. What nonsense!
It's clear as day what's REALLY going on here: This spike in melanoma rates
happened precisely when people began slathering themselves and their children
in chemical sunscreens - and continued to climb as they began spending all
their free time indoors, parked in front of television and computer screens.
The Less Sun We Get, The Higher The Disease Rates In Adults And Kids Alike
Current melanoma rates are HIGHEST in sun-starved states such as Connecticut,
New Hampshire, and Minnesota and LOWEST in sunny Texas, Arizona, and Nevada. So
forget the sun-hating propaganda and follow the science - follow the SUN - and
get outside each day, because the vitamin D you get from sun exposure is the
single best cancer-fighter around. And whatever you do, don't touch sunscreen -
they're actually packed with chemicals that are known to CAUSE cancer, not
prevent it. The only real "protection" you need is common sense: cover up or
head indoors before you turn pink.
Does Uv Exposure Decrease Risk Of Melanoma?
Two recent papers (2012) blame increased ultraviolet (UV) exposure for the
growing rates of melanoma in the UK. Not considered were other possible
explanations for the rising rates of melanoma, including the use of sunscreen,
especially at latitudes above 40º, and a combination of underdiagnosis in the past with over diagnosis more
recently. Melanoma mortality rates changed little in the U.S. between 1986 and
2001 while incidence rates more than doubled.
As noted in Parkin, Mesher and Sasieni (2011), chronic UV exposure may reduce
rather than increase melanoma risk. Both chronic UV irradiance and smoking are
thought to reduce the risk of melanoma through increasing elastosis (aging) of
the skin. Sunscreen can increase risk of melanoma at high latitudes because it
does not block non-erythemal solar radiation well, and reduces the formation of
skin elastosis. A recent paper reported that melanoma tumours recruit
fibroblasts in order to grow. Thus, it seems likely that elastosis impedes the
recruitment of fibroblasts, explaining the inverse correlation with smoking and
little change with chronic UV irradiance. Smoking rates in the UK have declined
since before 1975, with declines in lung cancer mortality rates for males, from
110 deaths/100,000/year in 1970-75 to 55 deaths/100,000/year in 2006. Lung
cancer mortality rates for females rose to 30 deaths/100,000/year in 1985 and
remained at that level through 2006.
There is also reasonable evidence that moderate solar UVB exposure and increases
in vitamin D intake reduce the risk of melanoma. Higher rates of poor health in
the northern portions of the UK, compared to the rates in the southern
portions, have been linked to lower solar UVB doses and lower vitamin D status.
Unfortunately, recent opinions on the role of UV irradiance as a cause of
melanomas and public awareness campaigns have apparently led to reduced serum
25-hydroxyvitamin D [25(OH)D] concentrations in the UK6. Solar UVB exposure is
a very important source of vitamin D in the UK, and there is a large body of
literature linking higher solar UVB exposure to lower rates of about 20 types
of cancer. Observational studies also report that prediagnostic serum 25(OH)D
concentrations are inversely correlated with breast and colorectal cancer
risks. One problem with prospective observational studies is that single values
of serum 25(OH)D from the time of enrollment are used whilst serum 25(OH)D
concentrations change with time; thus, prospective studies may underestimate
the effect of vitamin D in reducing the risk of cancer since vitamin D status
changes from baseline values as time increases.
The effect of solar UVB in reducing the risk of cancer in the UK can be
estimated from seasonal variations in serum 25(OH)D concentrations and the
relationships between serum 25(OH)D concentrations and incidence rates for
breast and colorectal cancer. Mean serum 25(OH)D concentrations for those aged
45 years living in the UK range from 35 nmol/l in February to 75 nmol/l in
September. Incidence rates for breast and colorectal cancer are 35% and 30%
lower, respectively, for the September concentration compared to those for the
February concentration. Thus, the actual annual reduction in incidence rates
for these two types of cancer with adequate vitamin D repletion could be about
half of these estimates.
Since there are many other types of cancer that are vitamin D sensitive with
similar geographic variations in the United States with respect to summertime
solar UVB doses, the overall reduction in cancer rates that could be achieved
with vitamin D repletion could be much higher than for just these two types of
cancer. In 2007, there were 988 male and 837 female deaths from melanoma in the
UK, and a total 71,336 male and 65,458 female cancer deaths. Thus, melanoma
accounted for 1.4% of male cancer deaths and 1.3% of female cancer deaths.
Assuming a 15% reduction in all-cancer incidence and mortality rates with
adequate solar UVB exposure would imply 20,500 reduced cancer deaths in 2007,
which is 11 times the number of melanoma deaths.
More recently, the higher rates of poor health in the northern portions of the
UK, compared to the rates in the southern portions, have been linked to lower
solar UVB doses and lower vitamin D status. Thus, it is highly likely that if
mean serum 25(OH)D concentrations were to be increased in the UK to 100 nmol/l,
through a combination of moderate solar UVB exposure, fortification of food
with vitamin D, and greater access to vitamin D supplements, cancer incidence
and mortality rates would fall dramatically, perhaps by 10-20%, and incidence
and mortality rates for many other types of disease might also prove to fall as
After this manuscript was prepared (January 2012), the "Leading medical research
charity Arthritis Research UK has reminded those groups with a potential
deficiency- such as people aged over 65, pregnant and breastfeeding women,
children aged six months to five years old, and those who rarely go outside &endash; that sunshine will increase their levels of vitamin D."
Dr. William Grant is an epidemiologist and founder of the nonprofit organization
Sunlight, Nutrition and Health Research Center (SUNARC). He has written over
140 peer-reviewed articles and editorials on vitamin D and health. Dr. Grant is
the Science Director of the Vitamin D Council and also serves on their Board.
He holds a Ph.D. in Physics from UC Berkeley.