Patients with
psoriasis have an increased risk of
cancer, which may be due to impaired immune surveillance, immune modulatory treatments, chronic
inflammation and/or co-risk factors such as
obesity. The increase in treatment-independent solid
cancers, including urinary/bladder
cancers, oropharynx/larynx, liver/gallbladder and colon/
rectal cancers, seem to be linked to alcohol and smoking.
Lung cancer and nonmelanoma
skin cancer are also increased in patients with
psoriasis. The risk of nonmelanoma
skin cancer increases with age and severity of
psoriasis. It is also higher in men, particularly for
squamous cell carcinoma, which may reflect previous exposure to PUVA and/or
ciclosporin. The risk of
cutaneous T-cell lymphoma is substantially higher in patients with moderate-to-severe
psoriasis.
Biologic therapies are independently associated with a slight increase risk of
cancer, but this is less than
ciclosporin, with the risk confounded by disease severity and other co-risk factors. The risk of
cancer from low-dose
methotrexate is likely minimal. In contrast,
acitretin is likely protective against a variety of solid and haematological
malignancies. The data on small molecule
therapies such as
apremilast are too immature for comment, although no signal has yet been identified. The decision whether to stop
psoriasis immune modulatory treatments following a diagnosis of
cancer, and when to resume, needs to be considered in the context of the patients' specific
cancer. However, there is no absolute need to stop any treatment other than possibly
ciclosporin, unless there is a concern over an increased risk of serious
infection or
drug-drug interaction with
cancer-directed
therapies, including
radiotherapy.