Abstract
This paper investigates the distribution of age at diagnosis of female breast cancer and its association with temporal trend, clinicopathologic and sociodemographic variables in the presence of two latent clusters that are directly unobservable. Such clusters help to identify two subpopulations of either young or old patients whose etiologies are thought to be different. A large sample drawn from registry data from the National Cancer Institute’s Surveillance, Epidemiology, and End Results program from 1990 to 2009 was analyzed using a two-component Gaussian mixture model. Evidence of a steady delay of age at diagnosis and an increasing proportion of young patients being diagnosed during the 20-year period was found. Histopathologic effects indicate that duct and lobular carcinomas differ significantly in regard to subpopulation membership, which confirms that they represent different etiologies. While the presence of estrogen receptor status in the model overlaps the effects of other important variables it is highly correlated with, it is found that the grade, extension and size of the tumor along with lymph node involvement status, race and marital status are important predictors of age at diagnosis. The results highlight the significant impacts that such features can have on breast cancer control efforts, and point to the importance of ensuring that medical decision making should use them along with an indicator of the age subpopulation a patient may belong to.
Highlights
Female breast cancer is a complex disease with different clinicopathologic features
Over the past three decades in the US, diagnostic methods have changed and female breast cancer etiology has evolved due to change in lifestyles and frequent screening
During the period of study, N = 446,726 diagnosed cases of female breast cancer were registered in the nine SEER registries considered here, which include Atlanta, Connecticut, Detroit, Hawaii, Iowa, New Mexico, San Francisco-Oakland, Seattle-Puget Sound and Utah
Summary
Female breast cancer is a complex disease with different clinicopathologic features. Over the past three decades in the US, diagnostic methods have changed and female breast cancer etiology has evolved due to change in lifestyles and frequent screening. One of the primary challenges of breast cancer epidemiology is to identify risk factors such as age at onset which may provide clues for understanding the etiologic mechanisms of the disease. Female breast cancer diagnosed at a young age tends to have worse prognosis, namely fast-growing, high grade and hormone receptornegative tumors (Anders et al 2008; Fei et al 2013; Partridge et al 2010), and as a consequence a higher cause-specific mortality (Aebi et al 2000; Albain et al 1994; Anders et al 2008; de la Rochefordiere et al 1993; El Saghir et al 2006; Holli and Isola 1997; Kollias et al 1997)
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