Parkinson disease (PD) patients had a lower frequency of skin cancers or any cancer prior to PD diagnosis compared to controls, suggesting that cancer may have a protective effect on PD risk, a recent study found. Researchers collected information regarding cancer diagnoses and diagnosis of PD from 971 unrelated PD patients and 478 controls. For PD patients, they examined cancers diagnosed before and after PD diagnosis separately, in addition to considering all cancer diagnoses. They found:

• In PD patients, the most common types of cancer were skin cancer (17.3% overall; 10.6% before PD), followed by nonmelanoma skin cancer (16.0% overall; 9.7% before PD), prostate cancer in men (12.8% overall; 9.2% before PD), breast cancer in women (10.6% overall; 6.3% before PD), and melanoma (2.4% overall; 1.1% before PD).

• Compared to controls, a significantly lower frequency of nonmelanoma skin cancer and any skin cancer was observed in PD patients.