Racial differences in breast cancer survival: the interaction of socioeconomic status and tumor biology

Socioeconomic factors and breast carcinoma in multicultural women

Breast carcinoma is the most common cancer in women in the U.S. and the second leading cause of cancer death in women. Furthermore, there are racial differences in breast carcinoma incidence, mortality, and survival rates. Social and economic factors within racial/ethnic groups are being examined as risk factors not only for breast carcinoma mortality and survival but also as determinants of the rate of incidence. Social and economic factors have been associated in the literature predominantly with cancer mortality and survival. When socioeconomic status (SES) is considered, certain studies suggest that racial disparities in breast carcinoma are smaller than when social and economic factors are examined alone, but these disparities still persist. Sources of data for this discussion include the National Cancer Institute (NCI) (the Surveillance, Epidemiology, and End Results [SEER] program, a group of population-based cancer registries that cover up to 14% of the U.S. population. SEER reports cancer incidence, mortality, and survival rates), the U.S. Bureau of the Census, the National Center for Health Statistics (NCHS), and numerous articles from the scientific literature. Socioeconomic factors or SES can be considered "cross-cutting risk factors" (i.e., they can be related to the risk of developing breast carcinoma [rate of incidence] as well as to the risk of dying [mortality] from this disease). They also are the risk factors that "cut across" racial and ethnic populations. Socioeconomic factors are related to breast carcinoma mortality and survival rates in multicultural women. Racial disparities in breast carcinoma mortality and survival rates can be explained partially by stage distribution at the time of diagnosis, which may be related to SES. For example, African-American women present with more advanced stage distributions for breast carcinoma than white women. Similarly, women of lower SES present with higher stage disease than women of upper SES who present with more localized breast carcinoma. The lack of data regarding the SES of cancer patients limits our understanding of the contributions of SES to cancer incidence and mortality rates. SES appears to be related to breast carcinoma incidence, mortality, and survival rates. Breast carcinoma mortality is higher in women of lower SES. Additional research on SES, race, culture, and the relation of these factors to cancer incidence rate is needed.

Is screening mammography effective in elderly women?

PURPOSE

Screening mammography is effective in reducing breast cancer mortality in women between the ages of 50 and 69 years. We sought to determine whether older women who undergo screening mammography have a decreased risk of metastatic breast cancer.

SUBJECTS AND METHODS

We studied 690,993 women aged 66 to 79 years who were California Medicare beneficiaries from January 1992 to December 1993, and who chose the fee-for-service plan. Health Care Financing Administration part B billing records were used to determine the use of screening mammography. The extent of breast cancer (in situ, local, regional, or metastatic) was ascertained for the 6,767 women who were diagnosed with the disease in 1993, using data from the California State Cancer Registry. For each type (extent) of breast cancer, the relative risk (RR) and 95% confidence (CI) of developing breast cancer was estimated by dividing the risk of its development in screened women by the risk in women who were not screened.

RESULTS

A total of 46% of women had mammography during the 2-year study period. In situ, local, and regional breast cancer were more likely to be detected among women who underwent screening mammography. For example, the relative risk of detecting local breast cancer in screened women was 3.3 (95% CI: 3.1 to 3.5). The risk of detecting metastatic breast cancer, on the other hand, was significantly reduced among women aged 66 to 79 years who underwent screening mammography (RR = 0.57, 95% CI: 0.45 to 0.72).

CONCLUSION

Screening mammography is associated with a decreased risk of detecting metastatic breast cancer among elderly women. Public health recommendations need to weigh the benefit of screening elderly women against the cost and potential harm from screening and treating early lesions that may have no effect on mortality.

Racial differences in breast carcinoma survival

BACKGROUND

Survival after breast carcinoma diagnosis is significantly worse among African American women for reasons unknown. The purpose of this study was to update reports on the National Surveillance, Epidemiology, and End Results Program and to examine the effect of race on breast carcinoma survival.

METHODS

Subjects were 135,424 women diagnosed with primary breast carcinoma between 1988-1995. Patient age, tumor stage at the time of diagnosis, hormone receptor status, tumor histology, menopausal status, and survival were compared by race category.

RESULTS

African American women diagnosed with breast carcinoma (n = 11,159) had a significantly increased risk of death from breast carcinoma and from all cancers compared with white women (n = 124,265), independent of the effects of other predictor variables. African American women were significantly younger at the time of diagnosis, with approximately 33% of the population age </= 50 years, compared with slightly <25% of the white women belonging to that younger age group. African American women were significantly more likely to present with advanced stages of breast carcinoma and, within each stage category, had significantly poorer survival compared with white women. African American women were significantly less likely to have tumors positive for estrogen or progesterone receptors, as well as histologically confirmed lobular and tubular carcinomas, whereas they were more likely to have inflammatory, medullary, and papillary histology compared with white women.

CONCLUSIONS

The results of the current study show that race is an independent predictor of survival from breast carcinoma. These findings are consistent with other large, population-based studies of racial differences in breast carcinoma survival and have been comported by studies of racial differences in the molecular biology of breast carcinoma, thus providing support for the epidemiologic credibility of the independence of the association.

Race and differences in breast cancer survival in a managed care population

BACKGROUND

African-American women with breast cancer have poorer survival than European-American women. After adjustment for socioeconomic variables, survival differences diminish but do not disappear, possibly because of residual differences in health care access, biology, or behavior. This study compared breast cancer survival in African-American and European-American women with similar health care access.

METHODS

We measured survival in women with breast cancer who are served by a large medical group and a metropolitan Detroit health maintenance organization where screening, diagnosis, treatment, and follow-up are based on standard practices and mammography is a covered benefit. We abstracted data on African-American and European-American women who had been diagnosed with breast cancer from January 1986 through April 1996 (n = 886) and followed these women for survival through April 1997 (137 deaths).

RESULTS

African-American women were diagnosed at a later stage than were European-American women. Median follow-up was 50 months. Five-year survival was 77% for African-American and 84% for European-American women. The crude hazard ratio for African-American women relative to European-American women was 1.6 (95% confidence interval [CI] = 1.1-2.2). Adjusting only for stage, the hazard ratio was 1.3 (95% CI = 0.9-1.9). Adjusting only for sociodemographic factors (age, marital status, and income), the hazard ratio was 1.2 (95% CI = 0.8-1.9). After adjusting for age, marital status, income, and stage, the hazard ratio was 1.0 (95% CI = 0.7-1.5).

CONCLUSION

Among women with similar medical care access since before their diagnoses, we found ethnic differences in stage of breast cancer at diagnosis. Adjustment for this difference and for income, age, and marital status resulted in a negligible effect of race on survival.

Impact of different adjuvant therapy strategies on quality of life in breast cancer survivors

Little is known about the long-term effects of adjuvant therapy on quality of life, sexual functioning and symptoms in breast cancer survivors. Between January 1996 and June 1997, we surveyed 1098 women who had been diagnosed with early stage breast cancer between 1 and 5 years earlier. The breast cancer survivors were recruited in two large metropolitan centers in the USA. They completed a survey battery that contained standardized measures of health-related quality of life (HRQL), depression, body image, sexual functioning, and symptoms. A total of 1096 had usable responses for these analyses. In this sample, n = 356 had received tamoxifen (TAM) alone, n = 180 received chemotherapy (CHEM) alone, n = 395 received CHEM + TAM, and n = 265 received no adjuvant therapy (NO RX). There were significant differences in the mean age of each group, with the TAM group being the oldest (mean 62.6 years) and the CHEM group being the youngest (mean 46.8 years). Both age and time since diagnosis were controlled for in all statistical analyses. We found no significant differences in global quality of life among the four treatment groups. For the MOS-SF-36, there were no significant differences on the subscale scores except for the physical functioning subscale (p = 0.0002); the NO RX group had the highest functioning. There were no significant differences in depression scores among the four treatment groups. The MOS-SF-36 physical functioning composite score differed by treatment group (p = 0.012); the NO RX group had a physical functioning composite score that was at the mean for a normal healthy population of women, while those in the adjuvant treatment groups scored slightly lower. The mental health composite score was not significantly different among the four treatment groups and approximated scores from the normal population of healthy women. There were no differences in body image scores among the four treatment groups; however, sexual functioning scores did differ (p = 0.0078) with patients receiving chemotherapy (either alone or with tamoxifen) experiencing more problems. Hot flashes, night sweats, and vaginal discharge differed by treatment (p = 0.0001); all symptoms were reported more often in breast cancer survivors on tamoxifen. Vaginal dryness and pain with intercourse also differed significantly by adjuvant treatment, occurring more often in survivors treated with chemotherapy. Overall, breast cancer survivors function at a high level, similar to healthy women without cancer. However, compared to survivors with no adjuvant therapy, those who received chemotherapy have significantly more sexual problems, and those treated with tamoxifen experience more vasomotor symptoms.

Breast cancer mortality in black and in white women: a historical perspective by menopausal status

To examine racial/ethnic differences in breast cancer mortality over time by menopausal status, data from published U.S. Vital Statistics tables (1950-1992) and the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute (1973-1991) were used to calculate age-adjusted breast cancer mortality and incidence rates. Overall, breast cancer mortality rates for white women were relatively stable from 1950 to 1992. In contrast, breast cancer mortality rates for black women increased during this period. Among premenopausal women there was no difference in breast cancer mortality between black and white women from 1950 to about 1975. However, after 1975, mortality rates in black premenopausal women increased, whereas those in white women decreased. Among postmenopausal women, breast cancer mortality was substantially lower in blacks than in whites in 1950. Between 1950 and 1992, rates in blacks increased and eventually exceeded rates in whites, which remained stable during this period. This excess in breast cancer mortality in black women is not explained by changes in breast cancer incidence rates. There is an unexplained epidemic of breast cancer mortality in black women that appears to differ somewhat by menopausal status. Reasons for temporal increases in breast cancer mortality seen only among black women need to be identified, as do reasons for the heterogeneity of trends by menopausal status.