A troubling feature of all medicines that affect the immune system is unintended consequences — worst-case scenario: cancer. It has been known for years that the immune-altering drugs used to treat diseases of the immune system like psoriasis and ulcerative colitis have the potential to cause cancer. Now comes a new study published in the Journal of the American Academy of Dermatology that looks at this problem again. The study was done in Northern California by the Kaiser Health Plan, noted for their organized approach to record keeping and data analysis. Click here for the abstract; if you wish the entire article request Dr. Stark in the box to the right to email it to you (he can’t post it for copyright reasons). They found in a group of several thousand patients receiving immune modulating drugs for psoriasis no overall increased risk of cancer, but found a 42% increased risk of squamous-cell carcinoma of the skin. This annoying cancer is not as serious as melanoma but neither is it as risk-free as basal cell, with which it is frequently grouped. Squamous-cell skin cancer will recur if not treated adequately and can metastasize in extreme cases. In patients whose immune systems are compromised — both by their disease and by the therapy used to control it — the risk of metastasis is higher, although in this study the authors did not examine that issue.
Dr. Stark’s comments: This study, well done by good investigators, reminds us that in medicine there is no such thing as free lunch. Not only are the drugs used extremely expensive, they have serious short-term side effects and this long-term side effect of a potentially serious skin cancer. Patients with psoriasis will have their skin examined as part of follow-up care, but patients with ulcerative colitis or regional enteritis (Crohn’s Disease) may not, but should.