Differences between African American (AA) and Caucasian (C) Patients Treated With Conservative Surgery and Radiation Therapy (CS+RT) for Early Stage Breast Cancer
There is a paucity of data regarding racial disparities in treatment and outcomes of AA compared to C breast cancer patients. We examined a large cohort of patients treated in our department with CS+RT to evaluate differences between these two racial groups.
Materials/Methods
Between 1975 and 2003, 2382 patients were treated with CS+RT at our institution. All patients were treated with CS+RT (whole breast RT med. dose 48 Gy + conedown, total med. dose 64 Gy), ± regional nodal RT and adjuvant chemotherapy at the discretion of the treating physicians. Of these, 2164 were C and 218 were AA. Patient data, (all clinical, pathologic, ER, PR, Her2/neu, treatment & outcome parameters) were entered into a database. In addition, p53 expression was analyzed from archived tissue on a total of 444 patients from the database. The data were analyzed to detect differences between the 2 racial groups.
Results
As of 9/06 the median follow up time was 7 years, with the AA group constituting 9% of the cohort. The percentage of patients who received chemotherapy and tamoxifen and type of chemotherapy delivered in each group was appropriate for the pathologic status, and did not differ significantly by race. The distribution of AA in the CS + RT cohort did not differ significantly from the distribution of AA women in our overall breast cancer population during this time interval, and AA and C groups presented with equivalent frequency of non palpable mammographically detected breast cancer (45% vs. 45%) reflecting similar treatment policies and access to care for AA women in our community. Despite this, there were significant differences found in the AA vs. C in age of presentation (under age 40: 19.7% vs. 12.2% p = 0.015), higher T stage (T2: 29% vs. 15%, p < 0.01), higher N stage (node +: 32% vs. 24% p = 0.038), ER negative (54% vs. 36%, p < .01), PR negative (58% vs. 47%, p = .017), and ‘triple negative’; (35% vs. 22%, p = .013). There were no significant differences in histologic subtype, number of lymph nodes removed, family history, or HER-2 status. Based on our tissue analysis, AA women were significantly more likely to have p53 positive tumors compared to C (32% vs. 13%, p = .003). By univariate analysis at 5 years, AA patients had higher rates of distant metastasis (17% vs 10%, p = .04), nodal relapse (4% vs 1%, p = 0.009), and breast relapse (13% vs. 7%, p = .07). However with multivariate adjustments for age, receptor status, and T/N stage, only nodal relapse was significantly higher among the AA women (RR = 3.171, CI = 1.232–8.164, p = .017).
Conclusions
In our large cohort of patients treated with CS+RT spanning over a 30 year period, despite apparent similarities in presentation and access to care, significant differences were found between AA and Caucasian patients to suggest that AA women have more aggressive disease. Possible biological explanations for these differences would include the lower rate of estrogen/progesterone receptors, higher rate of ‘triple negative’ tumors and higher detection of p53 mutation. Additional studies investigating the underlying biological/molecular differences are warranted to further explain the more aggressive clinical behavior of early stage AA breast cancer patients. To the best of our knowledge, this is the largest experience of conservatively managed AA patients reported.
1Yale University School of Medicine, New Haven, CT
2UMDNJ-Robert Wood Johnson School of Medicine, New Brunswick, NJ
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