Abstract LB-206: Breast cancer 21 -gene recurrence scores: Are there racial disparities in testing, scores, treatment, and outcome
Authors: Lund Mary Jo B. , Mosunjak Marina , Birdsong George G. , Gabram Sheryl , Rizzo Monica , Okoli Joel , Bumpers Harvey L. , Carlson Grant , Hearn Sherita , O'Regan Ruth M. 
Published: February 2011

Objectives: Guidelines recommend that the 21-gene recurrence score (RS) assay (Oncotype DX) be used to determine optimal treatment in patients with estrogen receptor positive(ER+), node negative (N-) breast cancer. Results are reported on a continuum and also trichotomized into 3 risk groups: low (0-18), intermediate (19-31) and high (&gt;31). The latter is most likely to achieve benefit from chemotherapy, minimal benefit with hormonal therapy, and to exhibit lower ER levels (intrinsically luminal B tumors). African American (AA) women have higher breast cancer mortality than white (W) women, in part due to higher prevalence of poor prognosis tumors and to access/treatment disparities. However, mortality differences persist among ER+ breast cancers, despite similar stage and treatment. We investigate differences between AA and W women in RS, treatment and outcome.

Methods: Tumor registry data from two Atlanta hospitals providing care for a majority underserved population identified AA or W female invasive breast cancers diagnosed 01/2006 - 07/2009. Registry data were augmented with medical record abstraction to acquire data on RS, treatment and outcome. Statistical analyses employed chi-square, fisher exact and t- tests.

Results: Of 797 cases (AA=666, W= 131), 317 were identified as Stage I-II, ER+N-, therefore eligible for RS testing (AA=245 [36.7%], W=72 [55.0%], p&lt;0.05) and 61 of those received RS testing (AA=31 [12.7%], W=30 [41.7%], p&lt;0.05). Patients distributed into risk groups as follows: Low=31, Medium=23, High=7; mean (median) RS=20.0 (18.0). Neither risk groups (Low=48.4% vs 53.3%, Medium=38.7% vs 36.7%, and High=12.9% vs 10.0% for AA and W women respectively, p=0.66) nor mean RS (AA=21.4, W= 19.7, p=0.55) differed. AA women were more likely to be diagnosed with larger tumors (Mean = 2.0 cm vs 1.5 cm, p&lt;0.05) with other tumor differences as follows: Stage I (58.1% vs 73.3%, p=0.08) and Grade I (16.1% vs 26.7%, p=0.27). Chemotherapy was received by 19 women (Low=4, Medium=9, High=6) and did not differ by race (AA=29.0%, W=33.3%, p=0.72). Hormonal therapy was received by all W women and 90% of AA women (p=0.78). After median follow-up of 17 months (range 1-45), 3 women recurred (2AA [RS=69, 19], 1W [RS=18]), both AA women subsequently died. The female with RS=69 received chemotherapy alone, the others hormonal therapy only.

Conclusion: Despite similar access and demographics, AA women were less likely than W women to be diagnosed with ER+N- breast cancers and to receive RS testing. Of those tested, RS scores and chemotherapy receipt did not significantly differ by race. AA women did tend to have poorer tumor prognostic factors, to have their cancers recur and to subsequently die. Our data suggest testing guidelines are not equivalently applied, that RS may not be as predictive nor treatment as efficacious for AA women with ER+N- breast cancers, reasons for which require further exploration.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-206.