Former President Jimmy Carter has been declared free of cancer after receiving Merck's ($MRK) Keytruda and radiation therapy for his metastasized melanoma, and research shows that Merck is likely to get a boost in sales as a result. A number of studies have documented a proven celebrity effect in healthcare. One study showed after journalist Katy Couric had an on-air colonoscopy, there was a 21% increase in colorectal screenings the next month. Singer Kylie Minogue's breast cancer diagnosis was later linked to mammography screening increases of 40% in Australia. More from FiercePharmaMarketing