Why are melanoma survivors found to be at increased risk of other cancers?

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Malignant melanoma is a form of skin cancer we are repeatedly warned about. As long as I can remember, just as things start to hot up, we are subjected to dire warning about the hazards of exposing ourselves to the sun’s rays. As a prelude to this this year, we have a recently published study which find that those that survive melanoma are at significantly increased risk of having another (compared to the general population) [1]. This study also found that melanoma sufferers are also at heightened risk of other cancers too, including those of the breast and colon, and several types of ‘lymph’ cancers referred collectively as non-Hodgkins lymphoma.

For a variety of reasons, I don’t think it comes as too much a surprise that melanoma survivors are at increased risk of a recurrence of this particular cancer. The effect of underlying factors such as environmental factors (e.g. sunlight exposure) and genetics do not go away overnight, if at all. And then we have the fact that melanoma sufferers are more likely than the general population to be repeatedly scrutinised for the presence of this cancer. In other words, some of the enhanced ‘incidence’ might be due to increased diagnosis, rather than increased risk per se.

But what about those other cancers? Why should melanoma survivors be at increased risk of cancers that have no direct link with melanoma?

One factor that demands our consideration, I think, is vitamin D. My overwhelming experience is that individuals who have had a diagnosis of melanoma become very sun-shy. They have usually been urged by medical professionals to take steps to minimise unprotected exposure to sunlight. This rationale is based on the widespread belief that sunlight causes melanoma. Actually, though, the link here is not as clear-cut as some would have us believe. See here for more about this.

Whether sunlight ‘excess’ is a potent factor in the development of melanoma is a moot point, I think. And what is all-too-often ignored is that fact that if we avoid the sun and slather ourselves in sunscreen when we’re in it, we run the risk of limiting the production of vitamin D in the skin. And higher levels of this nutrient and/or increased sunlight exposure are associated with a reduced risk of several cancers, including – as it happens – cancers of the breast and colon and non-Hodgkin’s lymphoma.

What this means is that when individuals become sun-shy, they are quite likely to increasing their long-term risk of several cancers, as well as several other conditions linked to sunlight/vitamin D including cardiovascular disease and multiple sclerosis.

I advise against burning, but I am vigorously opposed to the generally one-sided anti-sun propaganda we are fed on an annual basis.

One practice I question is the use of sunscreen. There is some thought that this might actually increase melanoma risk [2]. One reason for this is that use of sunscreen generally prolongs sunlight exposure. It has been suggested that while some sunscreens may block ‘tanning’ and burning UVB, they may allow enhanced overall exposure to UVA, excesses of which may induce skin cancer. In this way, some have suggested that sunscreens give a false sense of security.

One other potential issue with sunscreens is that they can stop an individual becoming habituated to the sun. I remember back in the 70s here in the UK using no sunscreen at all even during hot and sunny summers. Shade and appropriate clothing were used to avoid burning when necessary. And by the end of the summer I and my sun-loving would have turned deep brown. By the end of the summer, there seemed no need to take any precautionary methods at all against burning. Tanning is not just a cosmetic thing: it protects the skin and reduces the risk of damage and burning.

I may be looking back with rose-tinted spectacles, but what I see now is a vastly different relationship with sunlight. Even after a sunny holiday abroad I see many people, particularly kids, returning only marginally browner than when they left. Liberal use of sunscreen may well have something to do with this. The apparent lack of tanning is partly significant as it signifies skin that has not become used to sunlight. And this increases the apparent ‘need’ for sunscreen.

In a previous post I suggested that the preponderance of redheads in Scotland may be related to an evolutionary advantage with regard to vitamin D production in the skin. I also referred individuals to a book written by researcher Oliver Gillie which I think quite persuasively makes the point that some of the chronic disease burden in Scotland might be down to lack of sunlight. Oliver Gillie, like me, is concerned regarding the one-sided messages we tend to get re sunlight exposure. He has developed what he has coined ‘SunSafe’ advice.

Here it is:

1. Sunbathe safely and without burning – every day if you can.

2. The middle of the day is a good time for sunbathing in the UK.

3. Start by sunbathing for 2-3 minutes each side. Gradually increase for day to day.

4. Don’t use sunscreen while sunbathing.

5. If feeling hot or uncomfortable, expose a different area, cover up, move into the shade – or use sunscreen.

6. When abroad, where the sun is generally stronger, expose yourself for shorter times until you find out how much is safe.

7. Children benefit from sun exposure, but need guidance.

8. A tan is natural and is generally associated with good health.

The only part of this I personally disagree with is the suggestion in point 5 regarding resorting to sunscreen. Bearing in mind the potential hazards associated with sunscreen use, my preference would be to follow the preceding advice regarding covering up and/or seeking shade.

As I’ve stated before, I have not used sunscreen for over 20 years. My last recollection of sunburn was during a skiing holiday about 20 years ago. I sport a year-round tan and feel well habituated to the sun.

But I still have the capacity to burn, and I act accordingly. In the summer in southern Europe, for instance, I can often be found in middle of the day on a beach in a tee-shirt and straw hat. As the sun cools off during the afternoon, off come the tee-shirt and hat. I’ve learned over the years how to get my sun, and the benefits it promises, without sunscreen and without sunburn. I have a strong sense I’m healthier for it too.


1. Bradford PT, et al. Increased Risk of Second Primary Cancers After a Diagnosis of Melanoma. Arch Dermatol. 2010;146(3):265-272.

2. Garland CF, et al. Could sunscreens increase melanoma risk? Am J Public Health 1992;82:614-615

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