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"Speaking of Vitiligo..."

I have vitiligo, will I get skin cancer?

Saturday, July 19, 2014

I have vitiligo, will I get skin cancer?This question comes up in my clinic all the time. Vitiligo patients are frequently told by their dermatologists that they are at a high risk for skin cancer because they are lacking the natural protection of the skin pigment melanin against the sun’s harmful rays. It seems to be a reasonable warning, since we know that sun exposure increases the risk of skin cancer, particularly in younger people who have experienced severe burns. Also, recent studies reveal that the use of tanning beds increase the risk of melanoma, a deadly skin cancer. It is also true that the lack of pigment in the skin in vitiligo patients, which results from the loss of the pigment-producing cells called melanocytes, makes them more likely to burn when spending time in the sun.

So, it’s not surprising that dermatologists warn their vitiligo patients about an increased risk for skin cancer. The problem is that research studies don’t seem to support this warning. During my training in dermatology and when trying to learn as much as I could about vitiligo, I used to attend the “Vitiligo” lecture at the yearly American Academy of Dermatology meeting. Dr. James Nordlund, a long-term expert on vitiligo who began studying the disease with Dr. Aaron Lerner almost 40 years ago, was the main speaker. Every year he would say that, although it seems obvious that vitiligo patients are at an increased risk for skin cancer due to their loss of pigment, he rarely saw it in his patients. And he has seen a LOT of patients with vitiligo.

In fact, I distinctly remember him saying that he could count the number of vitiligo patients that he’s seen with skin cancer on one hand, and in all but one of those patients the cancer appeared in normally pigmented skin, suggesting it wasn’t even the pigment loss that caused it. Dr. Nordlund also studied patients with albinism, a completely different disease in which the patients have normal numbers of melanocytes, but have no pigment because the cells are missing a key protein required to make it. Albino sufferers get skin cancers VERY frequently, and can even die of this complication. But Dr. Nordlund noticed a distinct contrast between patients with each disease, as vitiligo patients exposed to extreme sun in Africa rarely developed cancer, while albino patients in the same sun often developed multiple cancers on their skin. He ended by saying he did not know WHY this was the case, but that this was his experience. And I was fascinated.

It was not long thereafter that a study performed in the Netherlands reported that patients with vitiligo appeared to be at a LOWER risk for skin cancer than healthy controls in comparison. In the study, they surveyed vitiligo patients over the age of 50 and their healthy partners as controls, asking about skin cancer risk factors (sun exposure, family history, etc), and whether they ever had a skin cancer. It turned out that the vitiligo patients reported 3 times fewer skin cancers (including melanoma, squamous cell carcinoma, and basal cell carcinoma) than their healthy partners, suggesting that vitiligo patients may be relatively protected from skin cancer. This lower risk was not simply due to staying out of the sun more, using more sunscreen, or by avoiding other known risk factors for cancer.

How could this be? The short answer is, we don’t know for sure. But there are some clues. Recent studies into the genetics of vitiligo revealed that versions of genes that INCREASE the risk for vitiligo simultaneously DECREASE the risk for melanoma, and vice-versa. This kind of makes sense, because vitiligo occurs when the immune system kills normal melanocytes in the skin, resulting in white spots that lack pigment (read more about this here). Therefore, if vitiligo patients have an overactive immune system that kills normal melanocytes, it makes sense that they are able to clear the abnormal melanocytes of melanoma. In fact, there are a few reports of patients with widespread melanoma that become spontaneously cured of their disease, and all of them have simultaneously developed vitiligo. Also, new treatments for melanoma that increase the immune attack of the tumors also cause vitiligo. So vitiligo protects against melanoma, which is good news. However why vitiligo protects from non-melanoma skin cancers like squamous cell carcinoma and basal cell carcinoma cannot be explained by these observations.

This seemed like the right time to write this blog entry, because I had a vitiligo patient in my clinic last week who was very afraid she was going to get skin cancer and she was relieved, to the point of tears, when I told her about this new information. In addition, today I read a post on the Vitiligo page on Facebook by a woman who was scared that her son would get skin cancer and was afraid to take him to the beach on vacation. I often give my patients this “good” news when I first see them in my clinic. And they always say, “That’s not what my other doctors told me!” It is completely understandable that dermatologists assume that the risk of skin cancer is high in patients with vitiligo, but the available evidence does not support this. Also, some dermatologists are reluctant to use light therapy in vitiligo patients, which is too bad because it is the most effective treatment that we have (read more about this here). Studies show that narrow-band UVB phototherapy is very safe and, as far as we can tell, does not increase the risk of skin cancer for patients, including those with vitiligo. I inherited the “Vitiligo” lecture at the AAD from Dr. Nordlund, and I also address this important issue, but now with these new studies as added proof.

HOWEVER, IT IS VERY IMPORTANT TO MAKE THIS CLEAR: Having vitiligo does not mean you cannot get skin cancer. It is still possible – remember, Dr. Nordlund DID have vitiligo patients with skin cancer, and I have one patient who has early signs of pre-cancer on the skin. I was also emailed by a prominent dermatologist who told me that he has had a few vitiligo patients with skin cancer in his career, and that I shouldn’t tell vitiligo patients to ignore sun protection completely. So it is still important to protect yourself from burning in the sun. And in addition to increasing the risk of skin cancer, it can make vitiligo worse!