Context: Small area (eg, subcounty) cancer mapping is one of the analytic services most commonly requested of cancer registries and local public health agencies, and difficulties in providing it have been noted to undermine public confidence. Although a great many statistical protocols have been published to enable this practice, none of them are in common use to generate information for the general public.
Objectives: To evaluate the utility of subcounty breast cancer mapping and articulate guidelines and a possible protocol for its implementation by cancer registries and local public health agencies.
Methods: We convened an Expert Advisory Group of breast cancer stakeholders from around California to elicit values, priorities, and preferred characteristics of protocols for proactive subcounty breast cancer mapping. Upon formulating a protocol, we applied it to 9 years of data (2000–2008) describing invasive breast cancer in California for evaluation by the Expert Advisory Group.
Results: Maps with subcounty resolution were seen to provide important information with a wide range of applications. Priorities included the avoidance of false-positive findings, scientific credibility, and the provision of information elucidating social and environmental characteristics. A protocol using Kulldorff's Scan Statistic along with postanalytic steps for refining results was elaborated; when applied to the data, 4 discrete regions with elevated rates of invasive breast cancer were identified and described.
Conclusions: Expert Advisory Group priorities were readily translatable into a scientifically rigorous protocol that protected confidentiality and avoided statistically unstable rate estimates. The resulting maps enabled participants to visualize geographically defined populations falling within and crossing county boundaries. These findings support the enactment of policies for the routine and proactive analysis of breast cancer surveillance data to provide subcounty information.
This study discusses the utility of subcounty breast cancer mapping and articulates guidelines and a possible protocol for its implementation by cancer registries and local public health agencies. The findings of a Breast Cancer Expert Advisory Group support the enactment of policies for the routine analysis of breast cancer surveillance data to provide subcounty information.
Public Health Institute, Richmond (Dr Roberts and Mss Kumar, Collins, King, and Wong and Mr Guo); Zero Breast Cancer, San Rafael (Ms Barlow); Breast Cancer Action, San Francisco (Ms Bichler); Between Women, Brawley (Ms Cady); Breast Cancer Fund, San Francisco (Dr Engel); California Health Collaborative, Fresno (Ms Garrett); Greenaction, San Francisco (Ms Harrison); Latinas Contra Cancer, San Jose (Ms Morieko), Alameda County Department of Public Health, Oakland (Dr Murgai); California State University at Fullerton (Dr Tanjasiri); and San Francisco County Department of Public Health (Dr Pierce), California.
Correspondence: Eric M. Roberts, MD, PhD, Public Health Institute, c/o Environmental Health Investigations Branch, 850 Marina Bay Pkwy, Bldg P, 3rd Floor, Richmond, CA 94804 (firstname.lastname@example.org).
This study was funded by the California Breast Cancer Research Program, University of California Office of the President (project 15UB-8405).
The authors declare no conflicts of interest.