Breast cancer clusters in the northeast United States: A geographic analysis

Martin Kulldorff, Eric J. Feuer, Barry A. Miller, Laurence S. Freedman

Research output: Contribution to journalArticlepeer-review

322 Scopus citations


High breast cancer mortality rates have been reported in the northeastern part of the United States, with recent attention focused on Long Island, New York. In this study, the authors investigate whether the high breast cancer mortality is evenly spread over the Northeast, in the sense that any observed clusters of deaths can be explained by chance alone, or whether there are clusters of statistical significance. Demographic data and age-specific breast cancer mortality rates for women were obtained for all 244 counties in 11 northeastern states and for the District of Columbia for 1988-1992. A recently developed spatial scan statistic is used, which searches for clusters of cases without specifying their size or location ahead of time, and which tests for their statistical significance while adjusting for the multiple testing inherent in such a procedure. The basic analysis is adjusted for age, with further analyses examining how the results are affected by incorporating race, urbanicity, and parity as confounding variables. There is a statistically significant and geographically broad cluster of breast cancer deaths in the New York City-Philadelphia, Pennsylvania, metropolitan area (p = 0.0001), which has a 7.4% higher mortality rate than the rest of the Northeast. The cluster remains significant when race, urbanicity, and/or parity are included as confounding variables. Four smaller subclusters within this area are also significant on their own strength: Philadelphia with suburbs (p = 0.0001), Long Island (p = 0.0001), central New Jersey (p = 0.0001), and northeastern New Jersey (p = 0.0001). The elevated breast cancer mortality on Long Island might be viewed less as a unique local phenomenon and more as part of a more general situation involving large parts of the New York City-Philadelphia metropolitan area. The several known and hypothesized risk factors for which we could not adjust and that may explain the detected cluster are most notably age at first birth, age at menarche, age at menopause, breastfeeding, genetic mutations, and environmental factors.

Original languageEnglish
Pages (from-to)161-170
Number of pages10
JournalAmerican Journal of Epidemiology
Issue number2
StatePublished - 15 Jul 1997
Externally publishedYes

Bibliographical note

Funding Information:
This study was funded in part by the Swedish Council for Research in the Humanities and Social Sciences. The authors thank Gina Day, Susan Devesa, Iris Obraras, and Susan Sturgeon, for valuable comments on an earlier draft of this paper, and Todd Gibson, Katherine Rand, and Gray Williams of Information Management Services Inc., for computer support


  • Breast neoplasms
  • Cluster analysis
  • Confounding
  • Epidemiologic methods
  • Geography
  • Parity
  • Statistics


Dive into the research topics of 'Breast cancer clusters in the northeast United States: A geographic analysis'. Together they form a unique fingerprint.

Cite this