These studies were conducted at Channing Laboratory in Boston, a joint facility of Harvard Medical School and Brigham and Women's Hospital in Boston, and at the Harvard School of Public Health. The week before, another group from the same laboratory reported in the Journal of the National Cancer Institute that a study of 14,916 male physicians concluded that men run the same risk. Giovannucci is also assistant professor in the Department of Nutrition at the Harvard School of Public Health. Last year, data from the investigation of male physicians also showed that men with the highest levels of IGF-1 had more than four times the risk of prostate cancer than those with the lowest levels. Another Channing Laboratory team concluded that premenopausal women with high IGF-1 levels have more than double the relative risk of breast cancer.
Younger women are at greatest risk.
This team was led by Susan Hankinson, an assistant professor of epidemiology at the School of Public Health and an assistant professor of medicine at the Medical School. In all these studies, blood samples were collected from 32,826 nurses and 14,916 physicians between 1982 and 1990. None of these people had cancer at the time. They were then followed by questionnaires for 6 to 14 years. These results raise concern about attempts to slow aging in older people by giving them growth hormone to increase their IGF-1.