RALEIGH, N.C. – The incidence of invasive squamous cell carcinoma has more than doubled among U.S. nonphysician health professionals in the last 20 years, with marked sex differences evident in body-site distribution.
Dr. Khang Nguyen said his meta-analysis of data drawn from the Nurses' Health Study, the Nurses' Health Study II, and the Health Professionals Follow-Up Study was spurred by the fact that the National Cancer Institute’s SEER (Surveillance, Epidemiology and End Results) database and other national databases that record cancer statistics don’t track squamous cell carcinoma (SCC).
"Much of what we know about the epidemiology of squamous cell carcinoma comes from studies from the 1990s and earlier," noted Dr. Nguyen of Brigham and Women’s Hospital, Boston.
To help rectify this situation, he and his coinvestigators analyzed cases of pathologist-confirmed invasive SCC in the roughly 121,000 female participants in the Nurses’ Health Study, the 117,000 in the Nurses’ Health Study II, and 51,000 men in the Health Professionals Follow-Up Study. There were 1,580 cases in the Nurses’ Health Study, 468 in the Nurses’ Health Study II, and 1,194 in the Health Professionals Follow-Up Study.
Among participants in the Nurses’ Health Study, the incidence of invasive SCC climbed from 40 per 100,000 person-years in 1987 to a peak of 120 per 100,000 person-years in 2005 before declining to 80 per 100,000 in 2007. Rates were lower in the Nurses’ Health Study II, a younger cohort. Among men in the Health Professionals Follow-Up Study, the incidence was 80 per 100,000 person-years in 1987, peaking at more than 160 per 100,000 person-years in 2002, and then falling back slightly to 140 per 100,000 person-years in 2007.
Invasive SCC occurred more often in the head and neck region among men, and in the thigh, buttock, legs, and feet region in women.
The significant risk factors for the malignancy, which emerged from a multivariate logistic regression analysis, included a history of painful or blistering sunburns (with an associated 2.2-fold increased risk) and a history of six or more sunburns in childhood. Other independent risk factors for invasive SCC were a family history of melanoma and lighter hair color.
The Nurses’ Health Study, the Nurses’ Health Study II, and the Health Professionals Follow-Up Study were funded by the National Institutes of Health. Dr. Nguyen’s analysis was funded in part by a grant from the Doris Duke Charitable Foundation.