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Aging population drives dramatic increase in Merkel cell carcinoma incidence
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The 95% increase in Merkel cell carcinoma incidence during a 13-year period at the start of this century appeared largely attributable to an aging population, according to study results.
For comparison, during the same period, melanoma incidence increased by 56% and incidence of all solid tumors increased by 15%.
Paul Nghiem, MD, PhD — head of the division of dermatology at University of Washington, George F. Odland endowed chair and affiliate investigator at Fred Hutchinson Cancer Research Center, and clinical director of skin oncology at Seattle Cancer Care Alliance — and colleagues used SEER data to assess and project Merkel cell carcinoma incidence trends.
The registry included 6,600 Merkel cell carcinoma cases in the United States from 2000 through 2013.
Nghiem and colleagues calculated an incidence rate of 0.7 cases per 100,000 person-years during 2013, equating to 2,488 cases per year. Incidence increased exponentially with age, ranging from 0.1 cases per 100,000 person-years for those aged 40 to 44 years, to 1 case per 100,000 person-years for those aged 60 to 64 years, to 9.8 cases per 100,000 person-years for those aged 85 years and older.
The researchers determined Merkel cell carcinoma incidence will continue to increase through 2025 because of the strong link between risk and advancing age. They projected 2,835 cases will occur in 2020 and 3,284 cases will occur in 2025.
HemOnc Today spoke with Nghiem about the results and their potential implications.
Question: How does an aging population contribute to increased Merkel cell carcinoma incidence?
Answer: Merkel cell carcinoma is an unusually age-sensitive cancer, with increasing age over 70 years leading to a 100-fold increase compared with those younger than 40 years of age. We are not sure why this effect is so strong, but a likely contributor is decreased immune function with age. This is the same reason we get shingles coming back later in life, as a reactivation of the chicken pox virus. Regardless, the relationship between age and Merkel cell carcinoma incidence has been known for a long time and is clearly real. The number of people aged older than 60 years or 70 years is increasing rapidly due to the demographics of the baby-boom generation.
Q: What can older individuals do to potentially prevent this malignancy?
A: In general, sun avoidance and use of sunscreen is helpful to decrease the risk for all types of skin cancer. If an unusual, firm bump arises on sun-exposed skin that does not look like other skin lesions a person has had, it is best to have it evaluated by a dermatologist or primary care physician. People who have had other skin cancers are at elevated risk for Merkel cell carcinoma, as well as melanoma.
Q: What kind of impact will this trend have on the health care system?
A: Because Merkel cell carcinoma is a rare cancer, even as its incidence doubles over 15 or 20 years, it will not have a huge impact on the health care system. A silver lining of this malignancy becoming less rare will be that more physicians will be familiar with its management and a higher fraction of patients will receive care that is optimally tailored for Merkel cell carcinoma, which is a quite unique and challenging cancer to manage.
Q: Are clinicians generally aware of this trend?
A: Often they are not. Most physicians have had little or no exposure to Merkel cell carcinoma, but those who care for skin cancers are increasingly aware. The fact there is now a drug that is approved for Merkel cell carcinoma — avelumab (Bavencio; EMD Serono, Pfizer) — has helped to expand awareness.
Q: What else is being done to increase awareness?
A: We have done our best to create web-based, reliable, data-driven resources — one example is www.merkelcell.org — that help point patients in the correct directions for getting appropriate care. Many physicians are writing review articles, which is also helpful.
Q: Can you describe the treatment landscape for Merkel cell carcinoma?
A: Over the past 2 or 3 years, there has been great progress in the management of Merkel cell carcinoma. Chemotherapy was the only option to treat advanced disease prior to last year. The chance that chemotherapy would control a patient’s advanced disease was only 5% by 1 year after therapy initiation. In contrast, the use of new immune-stimulating drugs such as avelumab — the only approved agent for Merkel cell carcinoma — increases the chances of advanced disease being under control or eliminated by about 10-fold. That is, at least half of patients treated with these immune-stimulating drugs will not have had their cancer come back by 1 year after starting treatment. Other results have shown that most of those responders will continue to benefit for 2 or more years, with studies still ongoing. – by Rob Volansky
Reference:
Paulson KG, et al. J Am Acad Dermatol. 2018;doi:10.1016/j.jaad.2017.10.028.
For more information:
Paul Nghiem, MD, PhD, can be reached at 850 Republican St., Brotman Room 240, Seattle WA 98109; email: pnghiem@uw.edu.
Disclosure: Nghiem reports consultant roles with EMD Serono and Pfizer, as well as research support to his institution from Bristol-Myers Squibb and EMD Serono.