Black women in US have lower survival rates from breast cancer than white women

Black women in the United States are less likely to survive breast cancer than white women, regardless of the stage at which the cancer is diagnosed, a study has found.

The biggest disparities were in women aged under 40 who were diagnosed as having stage one or unstaged disease. They were twice as likely to die as white women diagnosed at the same stage (Journal of Surgical Research 2008 Jun 23; doi: 10.1016/j.jss.2008.05.020).

Black women were less likely to have had surgical excision of their breast cancer and less likely to have radiation therapy.

“A better understanding of the patient, physician, tumour, and treatment factors contributing to the disparity in survival outcomes between black and white women may lead to interventions that reduce racial disparities in breast cancer survival,” say the authors.

“Our analysis, which controlled for several variables associated with survival, demonstrated significantly poorer survival for black women under 65 years of age at all stages of disease within each age group.”

The study, which aimed to see whether disparities exist at all stages of breast cancer and in all age groups, used data about 20 424 black and 204 506 white women diagnosed as having first primary breast cancer from two decades. A total of 56 773 women died, 28 802 (51%) from breast cancer.

The results show that black women were more likely than white women to be diagnosed in the under 40 (10.8% v 5.7%) and the 40-49 (24.6% v 18.9%) age groups, and white women were more likely to be diagnosed in the over 65 group (42.2% v 31.1%)

Black women in all age groups were significantly more likely than white women to be diagnosed at a more advanced stage and to have larger tumours, higher grade tumours, and positive lymph nodes. Black women were significantly less likely that white women to have oestrogen or progesterone receptor positive tumours and less likely to have received surgery or radiation therapy.

For all age groups and stages of cancer combined, the crude risk of death from all causes and the crude risk of death from breast cancer were higher in black compared with white women (1.52, 95% confidence interval 1.48 to 1.55, and 1.90, 1.83 to 1.96).

Black women were more likely to be diagnosed with late stage breast cancer in all age groups: “Late stage at diagnosis alone does not account for the differences in breast cancer specific mortality between black and white women. For the most part, black women under 65 years of age were more likely to die from their breast cancer within each stage of disease and within each age category,” the authors say.

They say that one of the most interesting findings was that the greatest disparity in deaths from breast cancer was between black and white women with early stage breast cancer.

“Black women in our study were less likely to undergo radiation therapy compared to white women across all age categories, and this could contribute to the survival disparity for in situ and early stage invasive disease since the increased local recurrence rate after lumpectomy without radiotherapy translates to a decrease in 15 year survival,” they say. “Suboptimal systemic treatment also may account for the poorer survival observed in black women with early stage disease.”