Among women under 35 with breast cancer, African-American and Hispanic women have more aggressive disease and are less likely to receive post-surgical adjuvant radiation therapy than non-Hispanic white women. Consequently, African-American and Hispanic women have a poorer prognosis and outcomes than non-Hispanic white women of similar age.

These are the conclusions of a new study that found racial and ethnic differences are apparent in the way women under age 35 with breast cancer are treated and in the clinical and genetic characteristics of the tumor. These discrepancies may account for disparities in survival that are observed among non-Hispanic white, Hispanic and African-American women in this age group.

The findings, which were published in the journal Cancer, indicate that among women under age 35 both African-American and Hispanic women presented with more aggressive forms of breast cancer and received different treatment modalities than non-Hispanic white women with similar disease. After controlling for demographic and tumor clinical characteristics, African-American and Hispanic women had an overall increased risk of death.

While the majority of breast cancer affects women over the age of 50, extremely malignant forms tend to afflict women under age 40 more commonly. This pattern is attributed to the observation that women with breast cancer under age 40 have a higher proportion of poor prognostic factors, such as large tumors, lymph node involvement, and genetic abnormalities. Also, available screening tests are less sensitive for women in this age group.

However, epidemiological data show that among women under age 35, African-American and Hispanic women are disproportionately affected by breast cancer. In one national hospital survey, 6.3% and 6.2% of all breast tumors treated at the participating hospitals were among African-American and Hispanic women under age 35, compared to only 2.8% for non-Hispanic white women under age 35.

Moreover, the Surveillance, Epidemiology and End Results Registries (SEER) show that the incidence rate is nearly two-fold higher among African-American women compared to non-Hispanic white women in this age group, and the mortality rate is more than three-fold higher in African-American women compared to non-Hispanic white women.

Shavers et al examined factors that may explain racial and ethnic variations in breast cancer outcomes among women under age 35. The authors analyzed population-based data collected both from the SEER Program from 1990 to 1998 and the SEER Patterns of Care (POC) study (1990, 1991, and 1995). In addition to demographic information, the analyses examined data on the tumor characteristics such as lymph node involvement, size, hormone receptor status, histology, chromosomal pattern, treatment modalities and outcome. Data were collected from 3,978 women aged 15-34 years (66.3% non-Hispanic white, 18.2% African-American, 15.5% Hispanic) of whom 275 were included in the POC study.

African-American and Hispanic women had a greater proportion of large tumors and more frequently had lymph node involvement, which indicates worse disease. Tumors from African-American and Hispanic women were more likely to contain abnormalities associated with a poor outcome. This included tumors that were less often estrogen-receptor positive, and more often aneuploid, with high S-phase fractions and poorly differentiated tumor cells.

Statistically significant racial and ethnic differences were also observed in the treatment of invasive breast cancer. African-American and Hispanic women were less likely to undergo axillary lymph node dissection, cancer-directed surgery, and adjuvant radiation therapy after breast conserving surgery, although they more often received Tamoxifen therapy for estrogen-receptor positive tumors. Notably, women with Medicaid were significantly less likely to receive adjuvant radiation therapy after breast conserving surgery.

Overall survival and disease-specific survival were significantly poorer for African-American and Hispanic women than non-Hispanic white women. Five-year overall survival was 42.1% for African-Americans, 43.1% for Hispanics, and 54.1% for non-Hispanic whites. Five-year disease specific survival was 66.6% for African Americans, 64.7% for Hispanics, and 76.5% for non-Hispanic whites. Analysis further showed that after adjustment for clinical tumor characteristics and treatment, African-American and Hispanic women remained at an increased risk of poorer overall survival.

The authors state, "we found racial/ethnic disparities in clinical presentation, treatment, and survival" of breast cancer for women under the age of 35. Future research, the authors suggest, should investigate specifically the clinical and genetic characteristics of tumors in African-American and Hispanic women that contribute to poorer survival as well as current screening practices among young women at high risk for breast cancer.

Moreover, future research should examine the specific reasons why, in the context of the current system of health care delivery, eligible women fail to receive appropriate adjuvant radiation therapy, "particularly in light of the higher prevalence of local recurrences that occur among women in this age group compared to older women."

The authors conclude, "a better understanding of factors that influence both racial/ethnic disparities in incidence and mortality from breast cancer in young women will facilitate the development of strategies to help eliminate this health disparity."

SOURCE:
Cancer, January 1, 2003