Patient and physician factors associated with Oncotype DX and adjuvant chemotherapy utilization for breast cancer patients in New Hampshire, 2010-2016

Disparities in OncotypeDx Testing and Subsequent Chemotherapy Receipt by Geography and Socioeconomic Status

BACKGROUND

OncotypeDx is a prognostic and predictive genomic assay used in early-stage hormone receptor-positive, HER2- (HR+/HER2-) breast cancer. It is used to inform adjuvant chemotherapy decisions, but not all eligible women receive testing. We aimed to assess variation in testing by demographics and geography, and to determine whether testing was associated with chemotherapy.

METHODS

For 1,615 women in the Carolina Breast Cancer Study with HR+/HER2-, Stage I-II tumors, we estimated prevalence differences (PD) and 95% confidence intervals (CI) for receipt of OncotypeDx genomic testing in association with and sociodemographic characteristics. We assessed associations between testing and chemotherapy receipt overall and by race. Finally, we calculated the proportion of eligible women receiving OncotypeDx by county-level rurality, census tract-level socioeconomic status, and Area Health Education Center regions.

RESULTS

38% (N = 609) of potentially eligible women were tested, with lower testing prevalences in Black (31%; PD, -11%; 95% CI, -16%-6%) and low-income women (24%; PD, -20%; 95% CI, -29% to -11%) relative to non-Black and higher income women. Urban participants were less likely to be tested than rural participants, though this association varied by region. Among women with low genomic risk tumors, tested participants were 29% less likely to receive chemotherapy than untested participants (95% CI, -40% to -17%). Racial differences in chemotherapy were restricted to untested women.

CONCLUSIONS

Both individual and area-level socioeconomics predict likelihood of OncotypeDx testing.

IMPACT

Variable adoption of OncotypeDx by socioeconomics and across geographic settings may contribute to excess chemotherapy among patients with HR+/HER2- cancers. See related In the Spotlight, p. 635.

Reproducibility and intratumoral heterogeneity of the PAM50 breast cancer assay

BACKGROUND

The PAM50 assay is used routinely in clinical practice to determine breast cancer prognosis and management; however, research assessing how technical variation and intratumoral heterogeneity contribute to misclassification and reproducibility of these tests is limited.

METHODS

We evaluated the impact of intratumoral heterogeneity on the reproducibility of results for the PAM50 assay by testing RNA extracted from formalin-fixed paraffin embedded breast cancer blocks sampled at distinct spatial locations. Samples were classified according to intrinsic subtype (Luminal A, Luminal B, HER2-enriched, Basal-like, or Normal-like) and risk of recurrence with proliferation score (ROR-P, high, medium, or low). Intratumoral heterogeneity and technical reproducibility (replicate assays on the same RNA) were assessed as percent categorical agreement between paired intratumoral and replicate samples. Euclidean distances between samples, calculated across the PAM50 genes and the ROR-P score, were compared for concordant vs. discordant samples.

RESULTS

Technical replicates (N = 144) achieved 93% agreement for ROR-P group and 90% agreement on PAM50 subtype. For spatially distinct biological replicates (N = 40 intratumoral replicates), agreement was lower (81% for ROR-P and 76% for PAM50 subtype). The Euclidean distances between discordant technical replicates were bimodal, with discordant samples showing higher Euclidian distance and biologic heterogeneity.

CONCLUSION

The PAM50 assay achieved very high technical reproducibility for breast cancer subtyping and ROR-P, but intratumoral heterogeneity is revealed by the assay in a small proportion of cases.

Chemotherapy refusal and subsequent survival in healthy older women with high genomic risk estrogen receptor-positive breast cancer

BACKGROUND

Patients with estrogen receptor (ER)-positive, HER2-negative breast cancer (BC), and high-risk 21-gene recurrence score (RS) results benefit from chemotherapy. We evaluated chemotherapy refusal and survival in healthy older women with high-RS, ER-positive BC.

METHODS

Retrospective review of the National Cancer Database (2010-2017) identified women ≥ 65 years of age, with ER-positive, HER2-negative, high-RS (≥ 26) BC. Patients with Charlson Comorbidity Index ≥ 1, stage III/IV disease, or incomplete data were excluded. Women were compared by chemotherapy receipt or refusal using the Cochrane-Armitage test, multivariable logistical regression modeling, the Kaplan-Meier method, and Cox's proportional hazards modeling.

RESULTS

6827 women met study criteria: 5449 (80%) received chemotherapy and 1378 (20%) refused. Compared to women who received chemotherapy, women who refused were older (71 vs 69 years), were diagnosed more recently (2014-2017, 67% vs 61%), and received radiation less frequently (67% vs 71%) (p ≤ 0.05). Refusal was associated with decreased 5-year OS for women 65-74 (92% vs 95%) and 75-79 (85% vs 92%) (p ≤ 0.05), but not for women ≥ 80 years old (84% vs 91%; p = 0.07). On multivariable analysis, hazard of death increased with refusal overall (HR 1.12, 95% CI 1.04-1.2); but, when stratified by age, was not increased for women ≥ 80 years (HR 1.10, 95% CI 0.80-1.51).

CONCLUSIONS

Among healthy women with high-RS, ER-positive BC, chemotherapy refusal was associated with decreased OS for women ages 65-79, but did not impact the OS of women ≥ 80 years old. Genomic testing may have limited utility in this population, warranting prudent shared decision-making and further study.

Hospital Rurality and Gene Expression Profiling for Early-Stage Breast Cancer among Iowa Residents (2010-2018)

Objective

Given the challenges rural cancer patients face in accessing cancer care as well as the slower diffusion and adoption of new medical technologies among rural providers, the aim of our study was to examine trends in gene expression profiling (GEP) testing and evaluate the association between hospital rurality and receipt of GEP testing.

Methods

Data from the Iowa Cancer Registry (ICR) were used to identify women with newly diagnosed, histologically confirmed breast cancer from 2010 through 2018 who met eligibility criteria for GEP testing. Patients were allocated to the hospitals where their most definitive surgical treatment was received, and Rural-Urban Commuting Area codes were used to categorize hospitals into urban (N = 43), large rural (N = 16), and small rural (N = 48). Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated using multivariable logistic regression to evaluate the association between hospital rurality and GEP test use, adjusting for demographic and clinical characteristics. The association between test result and treatment received was assessed among patients who received Oncotype DX (ODX) testing.

Results

Of 6,726 patients eligible for GEP test use, 46% (N = 3,069) underwent testing with 95% receiving ODX. While overall GEP testing rates increased over time from 42% between 2010 and 2012 to 51% between 2016 and 2018 (P _trend < 0.0001), use continued to be the lowest among patients treated at hospitals in small rural areas. The odds of GEP testing remained significantly lower among patients treated at hospitals located in small rural areas (aOR 0.55; 95% CI 0.43-0.71), after adjusting for demographic and clinical characteristics. ODX recurrence scores were highly correlated with chemotherapy use across all strata of hospital rurality.

Conclusions

GEP testing continues to be underutilized, especially among those treated at small rural hospitals. Targeted interventions aimed at increasing rates of GEP testing to ensure the appropriate use of adjuvant chemotherapy may improve health outcomes and lower treatment-related costs.

The impact of age and nodal status on variations in oncotype DX testing and adjuvant treatment

Oncotype DX (ODX) recurrence score (RS) is a validated tool to guide the use of adjuvant chemotherapy (AC) in hormone receptor+/HER2- breast cancer. In this analysis, we examine (1) characteristics associated with ODX testing and (2) the association between ODX RS and receipt of AC across age and nodal status. Women with HR+/HER2–, early-stage (T1-2, N0-1) breast cancers from 2010–2017 in the National Cancer Database were included. 530,125 met inclusion and 255,971 received ODX testing. Older women were less likely to receive testing; however, nodal positivity increased use of testing. High ODX RS was associated with increased mortality, though the association was not consistent across age and was most strongly associated with mortality among younger, node-negative women. Older women with high ODX RS, regardless of nodal status, were less likely to receive AC. Clinicians may be employing ODX RS to support treatment decisions against the receipt of AC.

Oncotype DX Test Receipt among Latina/Hispanic Women with Early Invasive Breast Cancer in New Jersey: A Registry-Based Study

Oncotype DX® (ODX) is a valid test of breast cancer (BC) recurrence risk and chemotherapy benefit. The purpose of this study was to examine prevalence of and factors associated with receipt of ODX testing among eligible Latinas/Hispanics diagnosed with BC. Sociodemographic and tumor data of BC cases diagnosed between 2008 and 2017 among Latina/Hispanic women (n = 5777) were from the New Jersey State Cancer Registry (NJSCR). Eligibility for ODX testing were based on National Comprehensive Cancer Network guidelines. Multivariable logistic regression models of ODX receipt among eligible women were used to estimate adjusted odds ratios (AOR) and 95% confidence intervals (CI) by demographic and clinicopathologic factors. One-third of Latinas/Hispanics diagnosed with BC were eligible for ODX testing. Among the eligible, 60.9% received ODX testing. Older age (AOR 0.08, 95% CI: 0.04, 0.14), low area-level SES (AOR 0.58, 95% CI: 0.42, 0.52), and being uninsured (AOR 0.58, 95% CI: 0.39, 0.86) were associated with lower odds of ODX testing. While there was relatively high ODX testing among eligible Latina/Hispanic women with BC in New Jersey, our findings suggest that age, insurance status, and area-level SES contribute to unequal access to genetic testing in this group, which might impact BC outcomes.