Patterns of 21-gene Assay Testing and Chemotherapy Use in Black and White Breast Cancer Patients

Abstract

Purpose

In women with early stage, estrogen-receptor (HR)-positive breast cancer, the 21-gene recurrence score (RS) assay quantifies recurrence risk and predicts chemotherapy responsiveness. Recent data suggest that not all women with early-stage, HR+ disease receive this testing. We examined socio-demographic, clinical, and attitudinal factors associated with RS testing receipt and the RS testing impact on chemotherapy use in Black and White patients.

Patients and Methods

Women with newly diagnosed invasive, non-metastatic breast cancer were recruited and interviewed to collect socio-cultural and healthcare process data; clinical data were collected from charts. Of the sample (n=359), 270 had HR-positive disease. Primary analysis focused on those with HR-positive node negative disease (n=143); secondary analyses included node positive women. Logistic regression models evaluated factors associated with receipt of RS testing and chemotherapy.

Results

Among women eligible for the 21-gene assay, 43% received RS testing. In multivariable analysis, higher age (OR=1.04 per one year increase; 95% CI: 1.01–1.08) was associated with RS testing adjusting for covariates. Chemotherapy use was 23%. In multivariable analysis, positive attitudes about chemotherapy and higher risk of recurrence were associated with chemotherapy use (p<.05).

Conclusion

Patterns of genomic testing may vary by age. Efforts to understand factors associated with low testing will be important.

Introduction

Breast cancer remains the most common cancer among US women, with more than 230,000 new diagnoses and 40,000 deaths each year, ¹ along with decrements in quality of life.^2–4 Half of newly-diagnosed patients present with estrogen-receptor positive and early-stage disease.⁵ Increased clinical genomic profiling of breast tumors, in combination with traditional factors such as age, tumor size, and grade, determine recurrence estimates and guide adjuvant treatment decisions.⁶ The 21-gene recurrence score (RS) assay (Oncotype DX; Genomic Health Inc., Redwood City, CA) is a validated test that quantifies risk of recurrence and predicts benefit from chemotherapy in patients with early stage, estrogen-receptor and progesterone-receptor positive (HR+) node negative breast cancer treated with Tamoxifen.⁷ The use of RS testing has been integrated into three sets of clinical guidelines.^6,8,9

Several studies demonstrate that the RS impacts treatment utilization.^10–14 Specifically, RS alters oncologists’ chemotherapy treatment recommendations in 25%–44% of cases,^11,13,15 usually from combined chemo-hormonal therapy to hormone therapy alone.^{10,12,16–18} Beyond decreasing chemotherapy, testing also results in more specific reclassification of women. With an accurate understanding of the severity, treatment can be tailored to a patient’s specific tumor.¹⁹ Ultimately, the RS can become one of the first commonplace genomic tests that shift patterns of care in routine practice.¹⁹

Recent studies suggest that not all women with early-stage, hormone-positive disease receive RS testing. Studies utilizing large cohorts have demonstrated that Black women are less likely to be tested than Whites.^19,20 Lund and colleagues (2012)²⁰ found that testing bias may attenuate racial differences in RS, and disparate outcomes may be explained in part by differences in RS, although compliance and pharmacogenomics also may play a role. Given persistent disparities in breast cancer survival,^21,22 even among HR positive women,²³ it may be critical to understand potential racial disparities in RS testing. Because socio-cultural factors as religiosity and medical mistrust have been associated with receipt of genetic risk assessment in minority women, we examine these factors in our study.^24,25 Such factors are regarded to influence both patient-provider interactions and decision-making in minority women.²⁶

Healthcare practice setting also appears to play a role in the receipt of testing ²⁷. Other healthcare related factors such as patient-provider communication may also impact receipt of RS testing. Patient-provider communication has been associated with receipt of cancer screening tests,²⁸ cancer treatment,^26,29 and other genomic tests.³⁰ Patients with better communication with their providers may be more likely to request the test, have a better understanding of the purpose and/or rationale of the test and thus be more likely to make decisions to have the test.^31,32 In a small sample of mostly White patients, Tzeng and colleagues³² found that receiving information about RS testing from an oncologist was associated with women’s willingness to receiving testing. We will expand knowledge in this area by including attitudinal and socio-cultural variables that are hypothesized to impact cancer behaviors particularly in Black women but have not been empirically examined within the RS testing context.

We hypothesized that Black women and those of lower socioeconomic status would be less likely to receive RS but that this would be attenuated after controlling for tumor characteristics. We also expected that women without RS would be more likely to have chemotherapy compared to those with RS, but that RS would be correlated with chemotherapy use among those with RS.

Methods

Setting and Population

This report is a part of a larger study that has been detailed elsewhere.³³ Briefly, after Institutional Review Board approval from all institutions, a convenience sample was recruited via hospitals in Washington D.C. (n=3), in Detroit (n=1), and self-referrals from outreach activities (e.g. fliers, posters, mailings) between July 2006 and April 2011. Since recommendations for Oncotype DX testing were added to NCCN and ASCO guidelines in 2007 we focused only on women who were diagnosed when the guidelines had integrated RS testing. Thus, participants diagnosed in 2006 were excluded from the analysis.^6,34

Eligible women were ≥ 21 years old and diagnosed with invasive non-metastatic disease for whom systemic adjuvant therapy would be considered with curative intent. Black women were oversampled to facilitate race comparisons and to investigate within race-group differences. Women with ductal and lobular carcinoma in-situ, distant metastasis, recurrent disease, second primaries, who were not English speakers, who did not self-identify as Black or White, or unable to provide informed consent were excluded.

A total of 678 potentially eligible patients were screened for the study, 477 were eligible and of that number 82.8% were interviewed and 350 (90.9%) had complete medical records. Women with HR negative cancers and those with Stage III breast cancer were excluded from analyses. There were 270 women with HR positive disease and 146 who were both HR positive and node negative; the latter group is the primary focus of this manuscript. ³⁴ We also explored RS patterns in the overall group of women recruited that included both node negative and node positive disease (n=270). The reason for including patients with node-positive tumors was to explore use of RS among women for whom testing was not standard practice to assess if some women may have requested or sought testing regardless of NCCN guidelines and/or recommendations.³⁵

Data Collection

Clinical research assistants confirmed eligibility and obtained consent for interviews and chart reviews. Interviews were conducted by trained staff using a standardized computer-assisted telephone survey that lasted about 50 minutes. The survey included information about socio-demographic factors, attitudes about therapy, socio-cultural factors, and interactions with providers. On average interviews were conducted within 14 weeks post definitive surgery. Treatment and clinical variables (e.g., 21 gene assay, etc.) were abstracted from medical records 12–18 months after interviews. Participants received a $25 incentive.

Measures

Outcomes were obtained from medical records and included RS (yes or no), hormonal use (yes vs. no), and chemotherapy use of any regimen (yes or no).²⁶ Among women with RS, we abstracted patients’ recurrence risk score and 10-year recurrence risk from medical records.

Socio-demographic variables were self-reported race, age, education, marital status, employment, education, and insurance type (private vs. public) status. Clinical factors abstracted from medical records were estrogen or progesterone receptor (HR) status (positive vs. negative), surgery type (lumpectomy or mastectomy), nodal status (positive or negative), pathological tumor size, and breast cancer stage categorized from I to III, which was categorized similar to other reports as positive, negative, or unknown.³⁶ Comorbidity was measured using the Charlson comorbidity index score.³⁷ Body mass index was calculated from data in the medical charts and categorized as either normal (kg/m² < 25) or overweight/obese (kg/m² ≥25).³⁸

Communication about chemotherapy was assessed using the Makoul Communication Scale (7-items) (Cronbach’s alpha: overall= .83).³⁹ The scale includes key dimensions of communication such as information-giving (e.g. “the doctor fully explained the risks of chemotherapy”) and physicians’ solicitation behaviors (e.g. “the doctor asked your opinion about taking chemotherapy”); scores above the median (=28) reflect self-reported perceptions of greater communication.

Chemotherapy attitudes items captured women’s perceptions about the efficacy and benefits (vs. side effects) of therapy (“chemotherapy does not help you live longer”) (Cronbach’s alpha overall= .60); scores above the median (=20) reflected positive attitudes.⁴⁰

The suspicion subscale (alpha=.84) of the Group-Based Medical Mistrust Scale was used to measure medical mistrust; higher scores indicated higher mistrust.⁴¹ Self-efficacy in understanding (alpha=.77) and participating in healthcare with providers (alpha=.76) were measured by the Communication Attitudinal Self-Efficacy Scale (CASE).⁴² Religiosity was analyzed based on the Lukwago Religiosity scale (alpha=.99) that measured women’s beliefs, values, and religious preferences; higher scores indicating higher religiosity.⁴³

Statistical Analysis

Study sample constitutes HR positive node negative breast cancer patients. Demographic, clinical, behavioral, and attitudinal characteristics of the participant women were described. Chi-square tests were conducted to examine bivariate associations with receipt of RS testing and chemotherapy initiation (yes or no). Independent sample t-tests were used for continuous variables. Multivariable logistic regression models were used to examine receipt of RS testing and also chemotherapy initiation. Variables significant (p<.05) in the bivariate analysis were included into the models. All models included race and models were adjusted for type of surgery and hormonal use. We used logistic regression to explore RS use in node positive women.

Result

Sample characteristics of the 143 women with HR positive and node negative cancer are detailed in Table 1. Participants’ ages ranged from 28 to 89 (m=55.9; SD=11.0) and 54% were Black. All patients were insured and most had private insurance. There were a few differences in socio-demographic factors by race. Compared to White women, a higher proportion of Black women had public insurance (76.25% vs. 23.75%, respectively), were in single/unpartnered households (73.68% vs. 26.31%) and had less than a college education (82.59% vs. 17.31%) (data not shown).

Table 1.

Sample Characteristics, Recurrence Score (RS) Test Status and Adjusted ORs for Likelihood of 21-Gene Assay Tests in HR positive and Node Negative Breast Cancer Women, N=143

Characteristic	Total N(%)	Yes RS N(%)	No RS N(%)	P value	Adjusted ORs 95% CI
Age Mean (SD)	55.9(11.0)	58.7(10.1)	53.8(11.3)	.011	1.04 (1.01, 1.08)†
Race
Black	78(54.5)	33(42.3)	45(57.7)	.647	0.71 (.35, 1.45)
White	65 (45.7)	30(46.2)	35(53.8)		ref
Married/Partnered
Yes	71(49.3)	32(45.1)	39(54.9)	.809
No	74(50.3)	31(43.1)	41(56.9)
Education
≤HS	26(18.2)	11(42.3)	15(57.7)	.843
>HS	117(81.8)	52(44.4)	65(55.6)
Highest Grade Completed
≤HS	26(18.2)	11(42.3)	15(57.7)	.248
Any college	41(28.7)	14(34.1)	27(65.9)
≥College degree	76(53.1)	38(50)	38(50)
Employed full-time
Yes	47(35.6)	22(46.8)	25(53.2)	.978
No	85(64.4)	40(47.1)	45(52.9)
Insurance
Private	84(66.1)	36(42.9)	48(57.1)	.259
Public	43(33.9)	23(53.5)	20(46.5)
Tumor Size
<2cm	92(66.2)	41(44.6)	51(55.4)	.989
≥2 cm	47(33.8)	21(44.7)	26(55.3)
Stage
I	86(67.2)	42(48.8)	44(51.2)	.902
II	42(32.8)	21(50)	21(50)
Surgery
Lumpectomy	97(67.8)	41(42.3)	56(57.7)	.536
Mastectomy	46(32.2)	22(47.8)	24(52.2)
Initiated Chemotherapy
Yes	31(21.7)	13(41.9)	18(58.1)	.788
No	112(78.3)	50(44.6)	62(55.4)
Hormonal Therapy
Yes	115 (80.4)	57 (49.6)	58(50.4)	.005	3.82 (1.38, 10.57)†
No	28 (19.6)	6 (21.4)	22(78.6)		ref
Initiated radiation therapy
Yes	86(60.1)	40(46.5)	46(53.5)	.468
No	57(39.9)	23(40.4)	34(59.6)
Comorbidity
No Comorbidity	42(29.4)	18(42.9)	24(57.1)	.853
One or more	101(70.6)	45(44.6)	56(55.4)
BMI
<25 Normal	46(34.8)	22(47.8)	24(52.2)	.886
≥25 Overweight/obese	86(65.2)	40(46.5)	46(53.5)
Chemo-Communication
Low	77(53.8)	36(46.8)	41(53.2)	.4843
High	66(46.2)	27(40.9)	39(59.1)
Chemotherapy Attitudes
Low	76(53.5)	39(51.3)	37(48.7)	.0728
High	66(46.5)	24(36.4)	42(63.6)
Understanding and participation in care
Low	61(46.6)	30(49.2)	31(50.8)	.694
High	70(53.4)	32(45.7)	38(54.3)
Maintaining a positive attitude
Low	60(46.5)	26(43.3)	34(56.7)	.502
High	69(53.5)	34(49.3)	35(50.7)
Suspicion of mistrust
Low	66 (40.9)	22(39.3)	34(60.7)	.377
High	81(59.1)	38(46.9)	43(53.1)
Religiosity
Low	66(50.0)	32(48.5)	34(51.5)	.729
High	66(50.0)	30(45.5)	36(54.5)
Race-based discrimination
Yes	47(32.9)	17(36.2)	30(63.8)	.181
No	96(67.1)	46(47.9)	50(52.1)

^†P<.05

Factors Associated with Receipt of RS 21 Gene Assay

Forty-three percent of the HR positive node negative sample had RS testing. There were no differences in receipt of RS testing by race (p >.05). Age was the only socio-demographic factor associated with RS testing. There was also no association of RS testing according to tumor characteristics, patient-provider communication or socio-cultural factors. There was a trend towards an association between chemotherapy attitudes (p=.07). In multivariate analysis, per 1 year increased in age was associated with a greater likelihood (OR: 1.04; 95%CI:1.01–1.08) of RS testing.

Exploratory Analysis

In the secondary analysis of both node positive and node negative women (n=270; 13% node positive, 87% node negative), 16% of those with node positive disease received RS testing (data not shown). In contrast to the primary analysis (node negative disease only), lower stage and smaller tumor size were associated with higher likelihood of having RS testing. Positive attitudes about chemotherapy were also associated with higher likelihood of RS testing. In multivariable analysis, women with private insurance (OR: 2.8; 95% CI: 1.05–7.27) were more likely to receive RS (data not shown).

Risk Profile of Study Participants

Among women with RS testing, risk of having recurrence in 10 years ranged from 0 to 58 (m=20.3, SD=11.6). Black and White women had similar mean RS scores (20.2±10.5 for Black vs. 20.5±12.9 for White; p=.897) (data not shown). Overall, 46% had scores that fell within the low risk category. Fifteen percent of Black women compared to 10% of White had high recurrence risk, while low to intermediate risk of recurrence was 85% among Blacks and 90% among Whites.

Chemotherapy Use and RS Testing in HR Positive Node Negative Women

Twenty-three percent of women with hormone positive and node negative disease initiated chemotherapy. Younger women were more likely to have chemotherapy compared to older women (p=.020). Women with high risk of recurrence were most likely to have chemotherapy (70.8%; p=.03) compared to the low risk group (3.3%) (Figure 1). More aggressive disease characteristics (i.e., higher stage, tumor size >=2cm) were associated with higher odds of having chemotherapy in bivariate analysis (see Table 1 in Appendix). Women with more positive attitudes about chemotherapy were more likely to initiate therapy than those with less positive attitudes (p<.001). In multivariable analysis, only attitudes about chemotherapy and risk of recurrence were significant controlling for other factors (p<.05).

Figure 1.

Overall Recurrence by Categories.

Appendix Table 1.

Chemotherapy Initiation Rates and Adjusted ORs in Women with HR Positive and Node Negative Breast Cancer, N=143

Characteristic	Total N(%)	Chemotherapy Initiated		P value	Adjusted ORs and 95% CI
		Yes N(%)	No N(%)
Age: Mean (SD)	55.9(11.4)	51.9(11.81)	57.1(11.07)	.020	0.96 (.88,1.05)
Race
Black	78(54.5)	19 (24.4)	59 (75.6)	.392	1.29 (.24, 6.98)
White	65(45.5)	12 (18.5)	54 (81.5)		ref.
Married/Partnered
Yes	71 (49.7)	13 (18.3)	58 (81.7)	.333
No	72 (50.3)	18 (25)	54 (75)
Education
≤HS	26 (18.2)	8 (30.8)	18 (69.2)	.265
>HS	117 (81.8)	23 (19.7)	94 (80.3)
Highest Grade Completed
≤HS	26 (18.2)	8 (30.8)	18 (69.2)	.481
Any college	41 (28.7)	9 (22.0)	32 (78.0)
≥College degree	76 (53.1)	14 (18.4)	62 (81.6)
Employed full-time
Yes	47 (34.8)	10 (21.3)	37 (78.7)	.886
No	85 (65.2)	19 (22.4)	66 (77.6)
Insurance
Private	84(66.1)	16(19.1)	68(80.9)	.413	2.12 (.25, 18.31)
Public	43(33.9)	11(25.6)	32(74.4)		ref
Tumor Size
<2cm	92 (65.5)	13 (14.1)	79 (85.9)	.0068	2.39 (.38 14.97)
≥2 cm	47 (34.5)	17 (36.2)	30 (63.8)		ref
Stage				.0128
I	86 (65.6)	14 (16.3)	72 (83.7)		1.01(.08, 12.32)
II	42 (34.4)	16 (38.1)	26 (61.9)		ref
Surgery
Lumpectomy	97 (67.8)	20 (20.6)	77 (79.4)	.663
Mastectomy	46 (32.2)	11 (23.9)	35 (76.1)
Hormonal Therapy
Yes	115 (80.4)	29 (25.2)	86 (74.8)	.008
No	28 (19.6)	2 (7.1)	26 (92.9)
Radiation therapy
Yes	86 (60.1)	20 (23.3)	66 (76.7)	.571
No	57 (39.9)	11 (19.3)	46 (80.7)
Comorbidity
No Comorbidity	42 (29.4)	9 (21.4)	33 (78.6)	.963
One or more	101 (70.6)	22 (21.8)	79 (78.2)
BMI
<25 Normal	46 (34.8)	8 (17.4)	38 (82.6)	.337
≥25 Overweight/obese	86 (65.2)	21 (24.4)	65 (75.6)
Chemo-Communication
Low	77 (53.8)	15 (19.5)	62 (80.5)	.495
High	66 (46.2)	16(24.2)	50 (75.8)
Chemotherapy Attitudes				<0.0001
Low Efficacy	76 (53.5)	5 (6.6)	71 (93.4)		ref.
High Efficacy	66 (46.5)	26 (39.4)	40 (60.6)		9.74 (1.39, 67.91)‡
Understanding Care participation in care
Low	61 (46.6)	15 (24.6)	46 (75.4)	.532
High	70 (53.4)	14 (20.0)	56 (80.0)
Positive attitude
Low	60 (46.5)	14(23.3)	46 (76.7)	.679
High	69 (53.5)	14(20.3)	55 (79.7)
Suspicion of mistrust
Low	56 (40.9)	11 (19.6)	45 (79.0)	.848
High	81 (59.1)	17 (80.4)	64 (21.0)
Religiosity
Low	66 (50)	13 (20.6)	53 (79.4)	.530
High	66 (50)	16 (25.4)	50 (74.6)
Discrimination
Yes	47 (32.9)	12 (25.5)	35 (74.5)	.450
No	96 (67.1)	19 (19.8)	77 (80.2)
Risk of recurrence
RS not tested	80(55.9)	18(22.5)	62(77.5)	.037	1.50 (.51, 4.43)
Low/Intermediate	55(37.7)	8(14.5)	47(85.5)		ref.
High	8(5.5)	5(62.5)	3(37.5)		14.23 (1.35, 149.92)

^‡P<.01

Table 2 shows the descriptive results for the women who underwent chemotherapy only. Among the women who had chemotherapy, 58.8% had a tumor size ≥2 cm, the majority (76.5%) were diagnosed with stage II, and had lumpectomy (70.6%).

Table 2.

Demographic and Clinical Characteristics of Women with Chemotherapy and Without RS Testing, N=17

Variable	N	%
Race
African American	15	88.2
White	2	11.8
Marriage Status
Married	4	23.5
Currently Single	13	76.5
Education
Less than High School	10	58.8
More than high school	7	41.2
Highest grade completed
<= high school	10	58.8
Any college	4	23.5
Bachelors and above	3	17.6
Employment status
Full time employed	2	14.3
Not full time employed	12	85.7
Tumor Size
>=2 cm	10	58.8
<2 cm	7	41.2
Stage
I	4	23.5
II	13	76.5
Surgery Type
Lumpectomy	12	70.6
Mastectomy	5	29.4
Radiation Therapy
Yes	15	88.2
NO	2	11.8

Discussion

In this observational study, less than half of breast cancer patients diagnosed between 2006 and 2011 with node negative, hormone receptor positive disease received RS testing. The rate of RS testing of node negative women fell within ranges found in other studies.^44,45 In concert with Nguyen and colleagues (2012) our results show that RS testing increased over the study period suggesting greater dissemination and/or adoption of testing.⁴⁵ Most of the initial studies of RS testing were in samples of mostly Whites (e.g., De Frank et al, 2013).⁴⁶ By including a proportional representative sample of Blacks our data adds to the growing body of literature that includes diverse breast cancer patients. Contrary to our hypothesis, we did not find differences by race or other sociodemographic factors among the group of women for whom tested was recommended (i.e., node negative).

Our null findings regarding the impact of race on RS testing are in contrast to Hassett and colleagues who found that Black patients were less likely to have RS.¹⁹ Lund and colleagues also found that Black women were half as likely as White women to receive RS in their sample but data were lacking on insurance and education.²⁰ This study did not have information about psychosocial attitudes. One explanation as to why we did not find racial disparities in RS testing may be that women in our study had higher SES backgrounds as noted by the level of education (only 18% had high school or less) and private insurance status among the Black and the Whites. Among women who were tested we did find that more Black women were in the highest risk category. This is concert with other analyses.^20,47

In general, few demographic factors have been consistently associated with RS.⁴⁴ Age was the only significant demographic variable in our study. The relationship between age and receipt of RS may relate to patient and/or provider practices. For example, patients and their physicians may be inclined to seek additional information about risk of recurrence in older women to avoid unnecessary chemotherapy given concerns about competing comorbidities or toxicities.⁴⁸ Studies that have examined the association between age and RS testing have produced mixed results.⁴⁹ For instance, DeFrank and colleagues found slightly higher RS testing rates in younger women.⁴⁶ In contrast, Hassett and colleagues found patients aged 50–59 had higher testing in comparison to patients below 50 or those over 70 years.¹⁹ Given equivocal findings to date this will be an important area for future research.

RS testing allows for a more accurate understanding regarding the tumor’s nature. Study findings supported our second hypothesis that women without RS would be more likely to have chemotherapy compared to those with RS (58.1% vs. 41.9%). Also, as expected women in the highest risk category who received RS, had the highest use of chemotherapy (55%) suggesting that RS results may have influenced treatment decisions. These results further support the studies that demonstrate that the RS impacts treatment utilization.^10–14 For example, RS information has been found to change oncologists’ chemotherapy treatment recommendations in 25%–44% of cases,^11,13,15 usually from combined chemo-hormonal therapy to hormone therapy alone.^10,11,16 Beyond this overall shift to less chemotherapy, testing also results in reclassification of some women with clinically low-risk disease to higher risk disease that requires chemotherapy and other women with clinically high-risk disease to a low risk categorization thus enabling them to avoid chemotherapy.¹⁹ Ultimately, the RS may represent one of the first genomic tests in common medical use that shifts patterns of care in routine practice.¹⁹

While chemotherapy utilization is largely influenced by clinical characteristics (e.g., tumor size, etc.), patients’ attitudes about therapy also appear to be important. Our data add to the limited literature about the influence of women’s attitudes on chemotherapy use as few studies have examined attitudes within the context of recurrence risk. We found that those with higher risk of recurrence had more favorable attitudes about the efficacy of chemotherapy. Due to the cross-sectional nature of the study, we cannot infer causation however, this finding may imply that women who received RS testing understood that chemotherapy had greatest benefit in women with tumors with high risk and, conversely, no demonstrated benefit if low risk of recurrence. Additionally, these women may have more discussions with their providers about chemotherapy. Richman and colleagues examined knowledge about RS testing in patients and found that while most women understood discussion about test results, about one third showed limited understanding, suggesting the need to improve risk communication.^32,50

It was interesting to note in the secondary analysis that 16% of women with node positive disease had RS testing, despite the fact that testing guidelines over the time of this study only recommended testing for those with node negative disease. Utility of testing among node-positive patients is currently the primary aim of an ongoing clinical trial (RxPONDER).⁵¹ Among this group, those with private insurance had access to testing although it was not clinical practice; data did not emerge until 2013 that would support this practice. Minority and lower SES groups had slower adoption of genetic testing for BRCA1/2 mutations.^52,53 Evidence of rapid or early uptake of new evidence-based treatment and diagnostic procedures/tests may lead to disparities.⁵⁴

Limitations of this study include our inability to attribute lack of RS testing based on physician’s orders. Physicians or patients were not queried about their decisions or communication about RS results. This will be an important area for future research. Also, some estimates had wide confidence intervals due to the modest sample size. We did not utilize a population-based sample so generalizability of results may be limited. Additionally, the cross-sectional design of the study prevents us from establishing causal relationships. Furthermore, the sample includes women who were insured so those without insurance may have different experiences with receipt of testing since some data suggests lower testing among uninsured women or those seen in other settings.⁵⁵ Because most large studies of RS testing lack information collected from patients, there are several strengths of our approach. These include oversampling of Black patients and inclusion of patient reported factors relating to communication and attitudes about chemotherapy. Although some socio-cultural and psychosocial factors were not associated with RS testing, it is important to assess the impact of these understudied factors. On balance this study extends knowledge about patient and clinical factors associated with receipt of RS testing and the relationship between receipt of RS testing and chemotherapy. In insured higher educated samples, racial disparities in RS may not be as prominent.

MicroAbstract.

Studies suggest that not all women with early-stage, hormone-positive (HR) disease receive RS testing. This paper examined the influence of socio-demographic, clinical, and attitudinal factors associated with receipt of RS testing and the impact of RS testing on chemotherapy use in Black and White patients. The study sample consisted of 270 HR positive women. Among those who were node negative, 43% received RS testing. No differences were found in RS testing by race but testing varied by age. The results of the study enhance the body of knowledge regarding RS testing in a diverse clinical sample by including self-reported psychosocial and attitudinal factors in patient's interactions with their providers.

Clinical Practice Points.

What is already known about this subject?

• The 21-gene recurrence score (RS) assay testing is a validated test integrated into clinical guidelines

• RS impacts treatment utilization in patients with early stage, hormone positive (HR+), node negative breast cancer

• RS is underused in some populations. Psychosocial factors associated with RS have been understudied

What are the new findings?

• Examination of psychosocial factors

• There were no race differences in RS use

• Age was the only significant demographic factor associated with RS use

• Women with higher risk of recurrence had more favorable attitudes about the efficacy of chemotherapy

How might it impact on clinical practice in the foreseeable future?

• Results of the study will enhance the body of knowledge regarding RS testing in a diverse clinical sample