Advances ingorpicif id new oppo ntie r vm epi *0_|1 _. 1;**R~i... aifA.:..f:a. tra d 1 h4 aft...-iti~~~~~~~~~W hgdethe mapping of health data is not new to epidemiologists, advances in geographic information system (GIS) technology provide new opportunities for epidemiologists to study associations between environmental exposures and the spatial distribution of disease. In addition to the conduct of ecologic studies in which environmental exposure information is compared with disease rates across regions at the group level, GIS

Population studies often estimate mammography use using women's self-reports. In one North Carolina county, we compared self-report surveys with a second method--counting mammograms per population--for 1987 and 1989. Estimates from self-reports (35% in 1987, 55% in 1989) were considerably higher than those from mammogram counts (20% in 1987, 36% in 1989). We then confirmed 66% of self-reports in the past year. Self-reported use is more accurate regarding whether a woman has had a mammogram than when she had it, but self-reports accurately measure change over time.

To determine mammography use among women with a broad range of ages, the authors surveyed women aged 30 to 74 years and physicians practicing primary care in two eastern North Carolina counties. Twenty-five percent of women in their 30s had ever had a mammogram, and 34% intended to have one in the coming year. From 45% to 52% of women in their 40s, 50s, and 60s had ever had a mammogram, and 55% to 57% intended to have one in the next year. Thirty-seven percent of women aged 70 to 74 years had ever had a mammogram, and 40% intended to have one in the following year. Nineteen percent of physicians reported screening nearly all women aged 30 to 39 years, and 14% screened few women aged 50 to 74 years. Younger women were more worried about breast cancer than older women and assessed their risk as higher, attitudes that were generally associated with higher mammography utilization. These community surveys suggest that mammography use may be excessive among younger women; older women continue to be underscreened. Cancer 67:2010-2014,1991, HE EVIDENCE for the usefulness of mammography T in screening women for breast cancer varies with age. For women aged 50 to 74 years, the evidence is strong,''2 and there is universal agreement among expert groups that these women should receive regular mamm~graphy.~-' For women in their 40s, the evidence is less clear,'-' ' and expert groups disagree in their screening recommendation^.^.^^^-^^'^ For women younger than 40 years of age, the low incidence of breast cancer13 and the low sensitivity of rnamm~graphy'~,'~ have led to a consensus that routine screening with mammography is not indicated. Few groups now recommend even a "baseline" mammogram for women younger than 40 years of age.I6 Several population surveys have assessed compliance with these recommendations among older women. Women aged 50 years and over have had less mammographic screening than is considered ideal.I7 Two recent surveys have found self-reported mammography use for women aged 40 to 49 years to be about the same as for older ~o m e n . '~, '~ No recent survey, however, has investigated mammography use by women aged 30 to 39 years. Also, although studies have examined the relationship between use of mammography and knowledge and attitudes about breast cancer, no study has investigated how these relationships might differ by a woman's age.We surveyed women and physicians practicing primary care in two eastern North Carolina counties to determine past and intended use of mammography among women aged 30 to 74 years. We asked whether knowledge and attitudes about breast cancer differed among women of different ages and whether these factors were associated with past use or intended use of mammography. To confirm these women's reports of mammography use, we questioned local physicians about their ordering of mammography for women in various age groups. 2010

Advances in geographic information system (GIS) technology, developed by geographers, provide new opportunities for environmental epidemiologists to study associations between environmental exposures and the spatial distribution of disease. A GIS is a powerful computer mapping and analysis technology capable of integrating large quantities of geographic (spatial) data as well as linking geographic with nongeographic data (e.g., demographic information, environmental exposure levels). In this paper we provide an overview of some of the capabilities and limitations of GIS technology; we illustrate, through practical examples, the use of several functions of a GIS including automated address matching, distance functions, buffer analysis, spatial query, and polygon overlay; we discuss methods and limitations of address geocoding, often central to the use of a GIS in environmental epidemiologic research; and we suggest ways to facilitate its use in future studies. Collaborative efforts between epidemiologists, biostatisticians, environmental scientists, GIS specialists, and medical geographers are needed to realize the full potential of GIS technology in environmental health research and may lead to innovative solutions to complex questions. Images p598-a Figure 2. Figure 3. A Figure 3. B Figure 3. C Figure 3. D Figure 3. E