[Skip to Content]
Access to paid content on this site is currently suspended due to excessive activity being detected from your IP address 54.205.150.215. Please contact the publisher to request reinstatement.
[Skip to Content Landing]
Views 363
Citations 0
Original Investigation
November 2016

Geographic Clusters of Basal Cell Carcinoma in a Northern California Health Plan Population

Author Affiliations
  • 1Division of Research, Kaiser Permanente Northern California, Oakland
  • 2Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts
  • 3Department of Dermatology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
JAMA Dermatol. 2016;152(11):1218-1224. doi:10.1001/jamadermatol.2016.2536
Key Points

Question  Are there geographic clusters of basal cell carcinoma among the membership of a large health plan in northern California?

Findings  In this study of data from a basal cell carcinoma registry, after adjustment for age, sex, and neighborhood socioeconomic status, 5 discrete geographic clusters of basal cell carcinoma emerged.

Meaning  Identifying geographic clusters can help inform future research on the underlying etiology of the clustering including factors related to the environment, health care access, or other characteristics of the resident population, and can help target screening efforts to areas of highest yield.

Abstract

Importance  Rates of skin cancer, including basal cell carcinoma (BCC), the most common cancer, have been increasing over the past 3 decades. A better understanding of geographic clustering of BCCs can help target screening and prevention efforts.

Objective  Present a methodology to identify spatial clusters of BCC and identify such clusters in a northern California population.

Design, Setting, and Participants  This retrospective study used a BCC registry to determine rates of BCC by census block group, and used spatial scan statistics to identify statistically significant geographic clusters of BCCs, adjusting for age, sex, and socioeconomic status. The study population consisted of white, non-Hispanic members of Kaiser Permanente Northern California during years 2011 and 2012.

Main Outcomes and Measures  Statistically significant geographic clusters of BCC as determined by spatial scan statistics.

Results  Spatial analysis of 28 408 individuals who received a diagnosis of at least 1 BCC in 2011 or 2012 revealed distinct geographic areas with elevated BCC rates. Among the 14 counties studied, BCC incidence ranged from 661 to 1598 per 100 000 person-years. After adjustment for age, sex, and neighborhood socioeconomic status, a pattern of 5 discrete geographic clusters emerged, with a relative risk ranging from 1.12 (95% CI, 1.03-1.21; P = .006) for a cluster in eastern Sonoma and northern Napa Counties to 1.40 (95% CI, 1.15-1.71; P < .001) for a cluster in east Contra Costa and west San Joaquin Counties, compared with persons residing outside that cluster.

Conclusions and Relevance  In this study of a northern California population, we identified several geographic clusters with modestly elevated incidence of BCC. Knowledge of geographic clusters can help inform future research on the underlying etiology of the clustering including factors related to the environment, health care access, or other characteristics of the resident population, and can help target screening efforts to areas of highest yield.

×