2015 data expands skin cancer insight

The past year brought disturbing news about the risk of skin cancer in all of us, a top dermatologist told colleagues in Hawaii recently.

Hensin Tsao, M.D., Ph.D.“All the way from Medicare billing to cells and DNA, we have new views about how the potential burden of skin cancer is truly extraordinary,” says Hensin Tsao, M.D., Ph.D., professor of dermatology at Harvard Medical School. “By just walking around outdoors, you’re getting a good share of ultraviolet radiation, creating mutations that are constantly poised to create skin cancer.”

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But there’s good news too: New immunotherapy treatments for metastatic melanoma are dramatically changing prognoses for patients.

Dr. Tsao presented his review of 2015 at the recent Maui Derm conference. In addition to his work at Harvard, Dr. Tsao is also clinical director at the Melanoma & Pigmented Lesion Center and director at the Melanoma Genetics Program, both at Massachusetts General Hospital.

The bad news

In terms of skin cancer overall, Dr. Tsao points to a recent study¹ that analyzed government health data in the U.S. Among the Medicare fee-for-service population, the study estimates, non-melanoma skin cancer procedures grew from 1.9 million in 2006 to 2.2 million in 2012. In total, the number of people treated with non-melanoma skin cancer was estimated to be 3.3 million in 2012.

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The age-adjusted skin cancer rate grew from 6,075 per 100,000 in 2006 to 7,320 per 100,000 in 2012. The study estimates an average of about 1.43 procedures per affected Medicare patient in 2012.

Notably, Dr. Tsao says, the 2012 figures included breakdowns for squamous cell and basal cell lesions. Their numbers were nearly identical at around 1 million each. “Most people have thought there are a lot more basal cell than squamous,” he says. “These estimates suggest they’re much closer in number than we used to think.”

Why didn’t we know this before? “It’s such a common cancer that it isn’t registered at a national level,” he says. Researchers had to pull Medicare data to come up with statistics.

But the statistics don’t reveal everything. They don’t say if the number of basal cell or squamous cell lesions are on the rise. Perhaps squamous cell carcinomas are being diagnosed and coded more than they have in the past, Dr. Tsao says.

Whatever the case, the number of diagnosed cases has risen. What’s going on? Dr. Tsao points to the lack of sunscreen use as an important factor. According to a recent survey sent to 6,012 adults, 60% of men and 40% of women rarely or never use sunscreen.²

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Even those who sunburn easily or have had skin cancer in the past year often fail to use sunscreen. The percentage of “always” and “most of the time” sunscreen users was just 31% in men who’d had skin cancer on the face in the past year; it was 71% for women. Of those who suffered severe sunburns on the face after an unprotected hour in the sun, only 36% of men always or mostly used sunscreen; the number was 61% for women.

“Men are much worse than women even in the face of strong sun sensitivity and skin cancer history,” Dr. Tsao says.

The study’s reliability is limited because it’s based on self reports; a third of those sent the survey didn’t answer at least half the questions.  

Another new study offers provocative insight into the risk of skin cancer that lurks in our bodies. Researchers performed advanced genetic analysis, Dr. Tsao says, and found that there is no “normal” sun-exposed skin.³

Based on an understanding of early mutations, he says, it’s clear that “every square centimeter of skin harbors mutations which are known to be associated with skin cancer.”

NEXT: The good news

The good news

Dr. Tsao did find positive news to report. According to him, there’s now talk of a “cure” for a devastating form of skin cancer, thanks to immunologic approaches. “Metastatic melanoma was thought of as incurable,” he says. “Now, every oncologist has experience with advanced disease patients who’ve gone on treatments and had responses they wouldn’t have had 10 years ago.”

Meanwhile, he says, researchers are focusing intense attention on patient selection and proper dosing and sequencing.

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But while the progress is promising, Dr. Tsao notes that dermatologists should be on the lookout for new challenges. They’re likely to need to monitor increased numbers of melanoma survivors, he says, and treatment-like the promising combination therapy of nivolumab and ipilimumab-can be highly toxic.

As a result, he says, dermatologists will face larger numbers of patients with cutaneous toxicities from drugs. “You don’t want them to get a second melanoma, and you want to improve their toxicities,” he says. “We’ll see dermatologists play more of a role in advanced disease.”

Gut reaction

Finally, Dr. Tsao says there’s one more melanoma-related research trend to keep an eye on. Early findings suggest that the gut microbiome plays a role in the response of the body to PD-L1-specific antibody (checkpoint blockade) therapy.⁴ While research in humans is needed to confirm suspicions raised by findings in mice, Dr. Tsao puts it this way: “Who would have thought the bacteria in your gut might moderate your responses to drugs for melanoma?”

References

1. Rogers HW, Weinstock MA, Feldman SR, Coldiron BM. Incidence Estimate of Nonmelanoma Skin Cancer (Keratinocyte Carcinomas) in the U.S. Population, 2012. JAMA Dermatol. 2015;151(10):1081-6.

2. Holman DM, Berkowitz Z, Guy GP, Hawkins NA, Saraiya M, Watson M. Patterns of sunscreen use on the face and other exposed skin among US adults. J Am Acad Dermatol. 2015;73(1):83-92.e1.\

3. Martincorena I, Roshan A, Gerstung M, et al. Tumor evolution. High burden and pervasive positive selection of somatic mutations in normal human skin. Science. 2015;348(6237):880-6.

4. Vétizou M, Pitt JM, Daillère R, et al. Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota. Science. 2015;350(6264):1079-84.