Trends in incidence and treatment for ductal carcinoma in situ in Hispanic, American Indian, and non-Hispanic white women in New Mexico, 1973-1994.

Abstract

Incidence rates of ductal carcinoma in situ (DCIS) breast carcinoma and the use of breast-conserving surgery (BCS) for its treatment show substantial geographic and ethnic variations nationwide. To the authors' knowledge, few studies have investigated incidence rates and treatment patterns in Hispanics and American Indians. The authors used data from the population-based New Mexico Tumor Registry to describe trends in DCIS incidence rates between 1973-1994 and investigate patient and physician characteristics related to BCS in a multiethnic population between 1985-1994. Multiple logistic regression was used to evaluate patient and physician factors related to receiving BCS. Incidence rates for DCIS in Hispanics were approximately 50% lower compared with non-Hispanic whites. American Indians had the lowest incidence rate. Beginning in 1985, incidence rates for Hispanics and non-Hispanic whites showed a 21% annual increase. Between 1990-1994, incidence rates in American Indians increased more than twofold. BCS increased 5.8% per year between 1985-1994, with 50% of Hispanic and non-Hispanic white patients treated with BCS in 1994. The strongest factor associated with receiving BCS was geographic location of treatment (P < 0.001). The odds of receiving BCS were 5.8 times higher in the northern third of the state compared with the southern third. No significant variation in BCS was found by ethnicity, rural/urban residency, socioeconomic status, or physician characteristics. Incidence rates for DCIS increased substantially in all three ethnic groups. The use of BCS was associated most strongly with the location of treatment, most likely reflecting differences in physician practices and treatment recommendations. Further research is needed to investigate the increasing incidence rates of DCIS and the determinants of BCS for the treatment of DCIS.