Pretty much all of us will have got the message by now that too much sunlight can cause skin cancer. However, a recent study conducted by leading cancer charity the Imperial Cancer Research Fund (ICRF) suggests that not all of us are taking heed of the advice to be wary of the sun. According to their report, about three quarters of us prefer a tanned look. Apparently, as many as one in seven of the population still want a tan even after experiencing the worry of potential skin cancer. The ICRF’s tone suggests that many of us are acting irresponsibly in the name of vanity. But are we? While sunlight may increase the risk of skin cancer, what is less well publicised is that it can help prevent illness too. There is quite a body of evidence that sunlight may protect us against several conditions including depression, heart disease and – believe it or not – some cancers. Is it possible that by shying away from the sun we might be doing ourselves more harm than good?
Skin cancer affects about 50,000 Britons every year. The majority of these are what are known as basal cell and squamus cell carcinomas (carcinoma is another name for cancer). These forms of cancer are usually treatable and are rarely life-threatening. The type of skin cancer which often proves fatal is known as malignant melanoma or ‘melanoma’ for short. Melanoma makes up about 10 p.c. of all skin cancers and kills about 2,000 Britons each year. Much of the health information regarding limiting sun exposure has been directed at reducing the incidence of melanoma.
There does indeed seem to be some evidence that burning and/or occasional exposure to intense sunlight, particularly in childhood, tends to increase the risk of melanoma. However, the relationship between sunlight exposure and melanoma is not as clear as you might think. For instance, in a study published in the medical journal Oncology in 1996, men who had most exposure to the sun through their work actually had a reduced risk of melanoma. The theory here is that regular, habitual exposure to sunlight can induce the skin to develop self-protective mechanisms in response to sunlight. Also, melanoma can often form in parts of the body that are not directly exposed to sunlight such as the soles of the feet. This again does not support the idea that there is a clear association between sunlight exposure and melanoma risk.
While the balance of evidence suggests that to avoid melanoma it is important to protect the skin from episodes of intense sun and particularly burning, how much protection is offered by more extreme avoidance is far from clear. Melanoma is a complex condition, and it is very difficult to know how effective sun avoidance is in reducing the incidence of this condition.
The drive to reduce the effects of sunlight on the skin has spawned the widespread use of sunscreens. The conventional wisdom is that by blocking the effect of the sun’s rays, sunscreen protects the skin from potentially cancer-inducing damage. Even this concept is open to question. At least two studies exist which have found that sunscreen use if associated with an increased risk of melanoma. It may be that although sunscreens may help prevent burning, they may nevertheless allow the transmission of forms of ultraviolet light associated with melanoma development. It therefore seems prudent that our efforts to protect ourselves when the sun is at it’s hottest should be by avoidance (e.g. staying indoors or under a parasol) or through the wearing of suitably protective clothing.
Despite all the negative messages we hear about sunlight, it’s hard to deny that most us prefer sunny weather, and generally like being out in it. However, the benefits of sunlight go far deeper than this. Sunlight appears to have a profound effect on mood, and lack of sunlight is thought to be the major factor in a form of depression which occurs in the darker months known as seasonal affective disorder. Sunlight is also important for the production of vitamin D, a deficiency of which is surprisingly common and may manifest as increased risk of bone fracture, muscle weakness and immune system problems. There is also some evidence that sunlight may reduce the risk of heart disease, and this may explain at least in part, why Mediterranean races such as the Southern Italians and Greeks enjoy low rates of this disease.
Perhaps even more surprising is the research that shows that sunlight exposure may actually reduce the risk of certain cancers. Studies show that a 10 p.c. reduction in sunlight exposure leads to a 6 ” 10 p.c. increase in breast cancer incidence and a 7 ” 12 p.c. increase in colon cancer cases. Even if we assume only a 6 p.c. rise in each of these two cancers, this still equates to about 2000 extra deaths in the UK each year. Bear in mind also that reducing sunlight exposure will only prevent a proportion of the 2000 deaths which occur each year as a result of melanoma. The evidence tends to suggest that while avoiding the sun may reduce the risk of melanoma, it may well increase our risk of cancer overall.
I have made this point in previous articles and will make it again here: In order to truly assess the impact of any factor on health we cannot focus solely on one part of the body and one type of disease. Challenging though it may be, what we need to do is look at the body and health as a whole. When we do this for sunlight, the balance of evidence really does suggest that it is generally beneficial. While avoiding excessive exposure to sunlight and sunburn may be important, I think the time has come to recognise the sun’s important health-giving properties.
