In the aftermath of Spiegel’s finding, numerous studies, including a follow-up he conducted in 2007, have failed to replicate his results or show a connection between optimism and disease outcomes in cancer. In one of the most rigorous, James Coyne, a professor of psychology at the University of Pennsylvania, studied nearly eleven hundred people with cancer and found no correlation among optimism, positive thinking, and cancer survival rates. Since then, most studies have suggested that positive thinking does not lead to better outcomes with breast cancer.
