3 ms·

I've always been told that "sunlight causes skin cancer" but after 20 minutes of looking around the Internet, I can't seem to find an actual scientific study th

by finkin1 13y ago

I've always been told that "sunlight causes skin cancer" but after 20 minutes of looking around the Internet, I can't seem to find an actual scientific study that confirms the statement to be true.

tristanj 13y ago
UV radiation found in sunlight can produce Pyrimidine dimers, which can lead to genetic mutations. Essentially, the UV radiation causes two DNA bases (Thymine or Cytosine) to fuse together and make that portion of DNA unreadable. Fortunately, our cells have mechanisms to repair such DNA damage, but if damage is acquired faster than the cell is able to repair itself, then permanent mutation is likely. If a cell acquires too many mutations, the mechanisms that prevent it from continuously replicating may fail, and the cell will replicate uncontrollably and spread throughout the body. This situation is known as cancer, and can occur in many different ways, making it fairly difficult to treat. There's a nice summary of the process listed here: http://theoncologist.alphamedpress.org/content/6/3/298.full http://theoncologist.alphamedpress.org/content/6/3/298.full
- finkin1 13y ago
  Right. This is the exact type of language I found everywhere else. Just because it "can" mutate which "can" become cancerous does not mean there is a direct correlation between UV radiation and skin cancer. I'd like to see some actual studies with controlled variables.
  - nitrogen 13y ago
    Are you suggesting that scientists should expose randomly selected subjects to UV light for their whole lives to see which ones get more skin cancer?
  - beloch 13y ago
    Getting cancer is like winning the lottery, and every time you go out in the sun, use a cleaning product, get an X-Ray, take an intercontinental flight, eat a banana, etc. you get a varying number of tickets. Unlike a lottery, once you finally "win" it's virtually impossible to figure out which ticket was "lucky". To do a controlled study on humans you'd need those humans to record an impractical amount of information about their day-to-day actions over their entire lives. This isn't going to happen anytime soon. To make matters worse, humans also use sunlight to synthesize Vitamin D, and low levels of Vitamin D are also correlated with cancer. So... Too much UV gives you cancer and too little can give you cancer if you don't get enough Vitamin D in your diet, which might also give you cancer. Okay... So use mice. Do mice respond exactly the same way to everything as humans? No... Probably not... Medical science is a bit like trying to figure out how to build the ultimate F1 car on a budget that only lets you work with Lada's.
  - glenra 13y ago
    One nice natural experiment is drivers. People who drive in the US get more sun on the left side of their face and their left arm. People who drive in Australia get more sun on the right side of their face and their right arm. If you measure which side people tend to get cancer on it seems to track this. http://health.yahoo.net/experts/dayinhealth/shocking-evidence-left-sided-skin-damage http://health.yahoo.net/experts/dayinhealth/shocking-evidenc...
chc 13y ago
http://en.m.wikipedia.org/wiki/Risks_and_benefits_of_sun_exposure http://en.m.wikipedia.org/wiki/Risks_and_benefits_of_sun_exp... has lots of references.
gilgoomesh 13y ago
I don't know where you looked but you were looking in the wrong place. An overwhelming majority of the studies ever conducted on the topic have found UV exposure to increase skin cancer risk. In fact, most studies are more interested in the mechanisms now than the risks, since the risks have been known for 50 years. Look through the list of papers here: http://scholar.google.com.au/scholar?q=uv+exposure+malignant+melanoma+risk&btnG=&hl=en&as_sdt=0%2C5 http://scholar.google.com.au/scholar?q=uv+exposure+malignant... If you want a really simple summary, from this meta study in 1997: http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0215(19971009)73:2%3C198::AID-IJC6%3E3.0.CO;2-R/full http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0215(1... > There was a significantly increased risk with sunburn at all ages or in adult life (OR = 1.91) and similarly elevated relative risks for sunburn in adolescence (OR = 1.73) and in childhood (OR = 1.95). Basically, if you have a history of sunburn (at any age) you nearly double the chance of getting malignant melanoma (the most deadly form of skin cancer). And here's one: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2363407/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2363407/ That indicates an 80% elevated risk of malignant melanoma from using sun tanning beds.

by finkin1 13y ago

I've always been told that "sunlight causes skin cancer" but after 20 minutes of looking around the Internet, I can't seem to find an actual scientific study that confirms the statement to be true.

tristanj 13y ago

UV radiation found in sunlight can produce Pyrimidine dimers, which can lead to genetic mutations. Essentially, the UV radiation causes two DNA bases (Thymine or Cytosine) to fuse together and make that portion of DNA unreadable. Fortunately, our cells have mechanisms to repair such DNA damage, but if damage is acquired faster than the cell is able to repair itself, then permanent mutation is likely. If a cell acquires too many mutations, the mechanisms that prevent it from continuously replicating may fail, and the cell will replicate uncontrollably and spread throughout the body. This situation is known as cancer, and can occur in many different ways, making it fairly difficult to treat. There's a nice summary of the process listed here: http://theoncologist.alphamedpress.org/content/6/3/298.full http://theoncologist.alphamedpress.org/content/6/3/298.full

finkin1 13y ago
Right. This is the exact type of language I found everywhere else. Just because it "can" mutate which "can" become cancerous does not mean there is a direct correlation between UV radiation and skin cancer. I'd like to see some actual studies with controlled variables.
- nitrogen 13y ago
  Are you suggesting that scientists should expose randomly selected subjects to UV light for their whole lives to see which ones get more skin cancer?
- beloch 13y ago
  Getting cancer is like winning the lottery, and every time you go out in the sun, use a cleaning product, get an X-Ray, take an intercontinental flight, eat a banana, etc. you get a varying number of tickets. Unlike a lottery, once you finally "win" it's virtually impossible to figure out which ticket was "lucky". To do a controlled study on humans you'd need those humans to record an impractical amount of information about their day-to-day actions over their entire lives. This isn't going to happen anytime soon. To make matters worse, humans also use sunlight to synthesize Vitamin D, and low levels of Vitamin D are also correlated with cancer. So... Too much UV gives you cancer and too little can give you cancer if you don't get enough Vitamin D in your diet, which might also give you cancer. Okay... So use mice. Do mice respond exactly the same way to everything as humans? No... Probably not... Medical science is a bit like trying to figure out how to build the ultimate F1 car on a budget that only lets you work with Lada's.
- glenra 13y ago
  One nice natural experiment is drivers. People who drive in the US get more sun on the left side of their face and their left arm. People who drive in Australia get more sun on the right side of their face and their right arm. If you measure which side people tend to get cancer on it seems to track this. http://health.yahoo.net/experts/dayinhealth/shocking-evidence-left-sided-skin-damage http://health.yahoo.net/experts/dayinhealth/shocking-evidenc...

chc 13y ago

http://en.m.wikipedia.org/wiki/Risks_and_benefits_of_sun_exposure http://en.m.wikipedia.org/wiki/Risks_and_benefits_of_sun_exp... has lots of references.

gilgoomesh 13y ago

I don't know where you looked but you were looking in the wrong place. An overwhelming majority of the studies ever conducted on the topic have found UV exposure to increase skin cancer risk. In fact, most studies are more interested in the mechanisms now than the risks, since the risks have been known for 50 years. Look through the list of papers here: http://scholar.google.com.au/scholar?q=uv+exposure+malignant+melanoma+risk&btnG=&hl=en&as_sdt=0%2C5 http://scholar.google.com.au/scholar?q=uv+exposure+malignant... If you want a really simple summary, from this meta study in 1997: http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0215(19971009)73:2%3C198::AID-IJC6%3E3.0.CO;2-R/full http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0215(1... > There was a significantly increased risk with sunburn at all ages or in adult life (OR = 1.91) and similarly elevated relative risks for sunburn in adolescence (OR = 1.73) and in childhood (OR = 1.95). Basically, if you have a history of sunburn (at any age) you nearly double the chance of getting malignant melanoma (the most deadly form of skin cancer). And here's one: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2363407/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2363407/ That indicates an 80% elevated risk of malignant melanoma from using sun tanning beds.