Sunscreen and Melanoma

Melanoma is the most deadly type of skin cancer, accounting for most skin cancer deaths in the US. As Ross pointed out in the comments section of the last post, there is an association between severe sunburn at a young age and later development of melanoma. Darker-skinned people are also more resistant to melanoma. The association isn't complete, however, since melanoma sometimes occurs on the soles of the feet and even in the intestine. This may be due to the fact that there are several types of melanoma, potentially with different causes.

Another thing that associates with melanoma is the use of sunscreen above a latitude of 40 degrees from the equator. In the Northern hemisphere, 40 degrees draws a line between New York city and Beijing. A recent meta-analysis found consistently that sunscreen users above 40 degrees are at a higher risk of melanoma than people who don't use sunscreen, even when differences in skin color are taken into account. Wearing sunscreen decreased melanoma risk in studies closer to the equator. It sounds confusing, but it makes sense once you know a little bit more about UV rays, sunscreen and the biology of melanoma.

The UV light that reaches the Earth's surface is composed of UVA (longer) and UVB (shorter) wavelengths. UVB causes sunburn, while they both cause tanning. Sunscreen blocks UVB, preventing burns, but most brands only weakly block UVA. Sunscreen allows a person to spend more time in the sun than they would otherwise, and attenuates tanning. Tanning is a protective response (among several) by the skin that protects it against both UVA and UVB. Burning is a protective response that tells you to get out of the sun. The result of diminishing both is that sunblock tends to increase a person's exposure to UVA rays.

It turns out that UVA rays are more closely associated with melanoma than UVB rays, and typical sunscreen fails to prevent melanoma in laboratory animals. It's also worth mentioning that sunscreen does prevent more common (and less lethal) types of skin cancer.

Modern tanning beds produce a lot of UVA and not much UVB, in an attempt to deliver the maximum tan without causing a burn. Putting on sunscreen essentially does the same thing: gives you a large dose of UVA without much UVB.

The authors of the meta-analysis suggest an explanation for the fact that the association changes at 40 degrees of latitude: populations further from the equator tend to have lighter skin. Melanin blocks UVA very effectively, and the pre-tan melanin of someone with olive skin is enough to block most of the UVA that sunscreen lets through. The fair-skinned among us don't have that luxury, so our melanocytes get bombarded by UVA, leading to melanoma. This may explain the incredible rise in melanoma incidence in the US in the last 35 years, as people have also increased the use of sunscreen. It may also have to do with tanning beds, since melanoma incidence has risen particularly in women.

In my opinion, the best way to treat your skin is to tan gradually, without burning. Use clothing and a wide-brimmed hat if you think you'll be in the sun past your burn threshold. If you want to use sunscreen, make sure it blocks UVA effectively. Don't rely on the manufacturer's word; look at the ingredients list. It should contain at least one of the following: titanium dioxide, zinc oxide, avobenzone (Parsol 1789), Mexoryl SX (Tinosorb). It's best if it's also paraben-free.

Fortunately, as an external cancer, melanoma is easy to diagnose. If caught early, it can be removed without any trouble. If caught a bit later, surgeons may have to remove lymph nodes, which makes your face look like John McCain's. Later than that and you're probably a goner. If you have any questions about a growth, especially one with irregular borders that's getting larger, ask your doctor about it immediately!

New Vitamin Bundle at Bariceuticals

Silvia Demeter, our friend and founder of the made-just-for-us Bariceuticals™ liquid vitamins has put together a new product bundle. Called "Cathy's Choice" the kit includes a 30 Day Supply of our famous liquid multi-vitamins and our pharmaceutical grade sublingual B-12 complex spray. You will also receive 30 day supply of our exclusive iron tabs. In this kit you will so receive a free sample of

Losing the Last 20 Pounds

Candace, age 36, was forty pounds heavier after giving birth to her third child than she had been before children. She lost the first twenty pounds after going on a series of different diets but she was not able to lose the last twenty pounds of 'baby weight' even though her youngest child was now four years old.

But after starting a regular exercise program she has succeeded in losing the last twenty pounds. She started by taking classes at the YMCA and by lifting weights but the pounds really started melting when she started running with a friend. It was really difficult to do the three mile run initially but she saw results quickly and this was very encouraging.

She's gone below her pre-pregnancy weight and now weighs 115 pounds at her height of 5'5". See her story and photo here.

Photo of jogger via Eleanza

I have hit the wall

I have dreams about NOT having my band. I dream I can eat whatever I want and I can eat it quickly. Donuts especially.

I am in a real mess guys. I have no will power left and all I can think about is BLOODY FOOD.

I don't need it... I WANT it. I just keep wanting something tasty, something savory, something sweet... just anything.

I need some advice to help me psychologically about this as its my mind doing overtime.

Here are some things that I think are niggling me and making me want food:

Money - just worried non specifically about not having enough really
My pupils exam results - especially a grade 8 student
Finishing work for the summer - on Saturday I wrap up for the year... which also brings us back to money or the lack of for 6 weeks.
DS's home education - next year its year 5 work. VERY worried about his handwriting.
My brothers wedding on 9th August and what I will look like, feel like and who I will be seen by (eg B'hurst People from school who I haven't seen for years and who last saw me at 9 stone something and don't want to look like a fat gone to pot, let myself go mother - which indeed I am!)
About the amount of people in the house - 8! Us three and Sue, Lotse, Csilla, Lilli and Trish and the fact that people are living on our drive in a caravan for heavens sake and we only have 1 loo in the whole house!
My hair. It's awful.

Theres a starter for you... come on then, sort me out.

How to Cause a Cancer Epidemic

A report came out recently showing that melanoma incidence has increased dramatically in the US since 1973, particularly among women. The authors suggested the rise could be due to increasing sun exposure, which I am highly skeptical of. The data he cites to support that idea are quite weak. I think the prevalence of vitamin D deficiency in this country suggests otherwise.

Melanoma is the most deadly form of skin cancer, and the only type that is commonly life-threatening. Its link to sun exposure is tenuous at best. For example, it often occurs on the least sun-exposed parts of the body, and its incidence is lower in outdoor workers.

What is the solution to rising melanoma incidence? Sunblock! Slather it on, ladies and gentlemen! No matter that we evolved outdoors! No matter that it may do nothing for melanoma incidence or mortality! No matter that you'll be vitamin D deficient! No matter that it contains known carcinogens! 30+ SPF, the more the better. Don't let one single deadly UV photon through.

The irony of all this is that if you believe the data on vitamin D, avoiding the sun would cause many more cancers than it would prevent, even if all melanoma were due to sun exposure.

Fish Oil and Asthma Weirdness

I read an interesting study today on fish oil and asthma. It's the result of a randomized controlled trial, the kind that can actually tell us about cause and effect.

In 1990, researchers assembled a group of 533 pregnant women and divided them into three groups. One group received 4g/day fish oil in capsules, one group got 4g/day of olive oil in capsules, and the third group got no oil. They were told to take the capsules from gestational week 30 until delivery. The 16 year-old children of women who took fish oil capsules during pregnancy had a 63% lower rate of asthma than the olive oil group, and an 87% lower rate of allergic asthma. Pretty straightforward.

Now for the weirdness. The no oil group actually did better than the other two groups, with a 71% lower asthma rate than the olive oil group, and no cases of allergic asthma whatsoever! The result was not statistically different from the fish oil group however. So we have just gone from a result that suggests fish oil is protective, to one that suggests fish oil is neutral and olive oil is detrimental!

The result is really hard to believe, especially since Mediterranean countries with high olive oil intakes don't have elevated rates of asthma. It was also hard for the authors to believe, so they invoked a concept called "contamination bias". In this case, what that means is that the no oil group may have been eating more fish than the olive oil group.

It could have happened because they had been informed of the study's hypothesis (this was required by the Danish Scientific Ethical Committee System). They knew they weren't getting fish oil, they knew there was preliminary evidence that fish oil protects against preterm birth and heart disease (in the Inuit, incidentally), so the authors speculate that they went out and started eating fish. This didn't happen in the olive oil group because according to a questionnaire, half of them thought they were getting fish oil already!

I will say, in favor of this hypothesis, that the no oil group looks remarkably like the fish oil group in terms of the rate and age of onset of asthma. I think the result needs to be replicated before we can really say what happened. It's unfortunate, because it was a large, well-designed study. In the meantime, keep on eating fish.

Thanks to snowriderguy for the CC photo

How to Dress to Minimize a Large Bust

Here's a nice video by Katie Stiles on how to dress to minimize and flatter a very large bust. She shows us five before and after outfits and tops.



Via Before and After TV