If you’re wondering whether your psoriasis—or your psoriasis treatment—might be increasing your risk for cancer, talk to your dermatologist.
That’s the advice of Dr. Zelma C. Chiesa Fuxench, a dermatologist at the University of Pennsylvania and the lead author of a new study exploring the association between cancer and psoriasis.
Her study found that patients with psoriasis may be more at risk of developing cancer, particularly certain cancers like lung cancer, lymphoma and non-melanoma skin cancer compared to patients who do not have psoriasis. The results echo findings from previous research identifying cancer as a comorbidity, or related condition, of psoriatic disease.
But Chiesa Fuxench said doctors are still investigating whether the risk comes from the disease itself or from psoriasis treatments that affect the immune system.
“Multiple studies show that some immune therapies can be associated with an increased risk of cancer,” Chiesa Fuxench said. At the same time, she noted, research indicates that chronic inflammation, as is seen with psoriasis, can also create conditions that promote the growth of tumors.
Treating your psoriasis can reduce your inflammation, but patients might wonder whether treatment itself may create a new problem.
How can you sort through the evidence and figure out what’s right for you? Work with your doctor to determine the best way to manage your disease and monitor your specific risk factors, Chiesa Fuxench suggested.
“When patients are deciding to come in for treatment, it’s important to come in with an open mind and have a very open discussion with your physician about your expectations for treatment and your concerns regarding risks associated with therapy,” said Chiesa Fuxench.
Overall risk for cancer is low
Chiesa Fuxench and her colleagues used records from The Health Improvement Network, a large medical records database from the United Kingdom, to analyze cancer risk. The study included 937,716 people without psoriasis and 198,366 people with psoriasis. Of the psoriasis patients, 186,076 were classified as having mild disease, while 12,290 were classified as having moderate-to-severe disease.
“When you look at all cancers combined—and we looked at a lot of malignancies—overall, your risk is low,” Chiesa Fuxench said. In an analysis including all cancers except non-melanoma skin cancer, psoriasis patients had about a 6 percent increased risk of developing cancer compared to those without psoriasis. Researchers did not find an increased risk for some well-known cancers, such as breast cancer, colon cancer, prostate cancer and melanoma, Chiesa Fuxench noted.
Dr. Zelma C. Chiesa Fuxench
But they did find a greater risk among psoriasis patients for developing certain cancers including lymphoma, lung cancer and non-melanoma skin cancer.
According to the results, psoriasis patients had a 34 percent increased risk of developing lymphoma. To put that in perspective, about 0.2 percent of Americans will be diagnosed with Hodgkin lymphoma and about 2.1 percent of Americans will be diagnosed with non-Hodgkin lymphoma at some point in their lives, according to 2010-2012 data from the National Cancer Institute.
Psoriasis patients in the study had a 15 percent increased risk of developing lung cancer. However, this risk was not as high for patients who had never smoked, researchers found. According to the same National Cancer Institute data, about 6.6 percent of Americans will develop lung or bronchus cancer at some point in their lives.
According to the American Academy of Dermatology, non-melanoma skin cancer is the most common cancer in the United States. Psoriasis patients in the study had a 12 percent increased risk of developing non-melanoma skin cancer, researchers found.
Separating treatment from disease severity
For all three of these cancers, the risk was higher for patients with moderate-to-severe disease. However, Chiesa Fuxench explained, that doesn’t necessarily mean that more severe disease equals more cancer risk.
Researchers classified patients’ disease severity based on the treatments they were prescribed. Patients on systemic treatments, such as methotrexate, phototherapy, acitretin or a biologic, were categorized as having moderate-to-severe psoriasis while those who were not on these treatments were categorized as having mild psoriasis.
This means that, for the purposes of this study, it’s tough to know if the disease severity or the treatment played a part in cancer risk.
“It’s difficult from our study to pinpoint that exactly,” Chiesa Fuxench said. She and her colleagues are currently working on a new study that will analyze the relationship between treatment and cancer risk more closely.
How can you reduce your risk?
No matter what’s causing the risk, patients can take steps now to reduce their risk factors.
For example, Chiesa Fuxench said, to reduce the risk of skin cancer, patients might “be more proactive in using sunscreen or trying to stay out of the sun.”
Doctors can help their patients reduce their risk too. For instance, Chiesa Fuxench said doctors might need to tell a psoriasis patient who smokes, “‘we need to come up with a plan to help you quit smoking, and do everything we can to keep you healthy.’”
Chiesa Fuxench received the National Psoriasis Foundation’s Mark G. Lebwohl Medical Dermatology Fellowship in 2013 and an NPF Amgen Medical Dermatology Fellowship in 2014. The study was funded in part through Chiesa Fuxench’s fellowship support.
Additional funding sources for the study include an unrestricted grant from Pfizer Pharmaceuticals to the Trustees of the University of Pennsylvania; Training Grant 5T32GM075766-09 from the National Institutes of Health for Dr. Chiesa Fuxench; and Grant K24-AR064310 36 from the National Institute of Arthritis and Musculoskeletal and Skin Disease for Dr. Joel Gelfand, senior author of the study.
The study was published in the journal JAMA Dermatology in December.
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