Abstract P3-09-09: Assessing utility of breast cancer risk assessment tool in comparison to Tyrer-Cuzick model for determination of breast cancer risk and implications for chemoprevention

Background

Despite findings that the Tyrer-Cuzick (IBIS Breast Cancer Risk Evaluation Tool or TC) model is more predictive of breast cancer risk than the Gail model (NCI maintained Breast Cancer Risk Assessment Tool or BCRAT), BCRAT is commonly clinically used as per the United States Preventive Services Task Force (USPSTF), with a 5-year risk for breast cancer (BC) of greater than 3% on BCRAT, the benefits of preventive medication likely outweigh the risks. We aimed to compare the models, 1: to see if a 10 year risk estimate per the TC model reliably correlated with the 3% 5 year risk per BCRAT, and 2: to analyze the subset of patients with atypical hyperplasia (AH) and lobular carcinoma in situ (LCIS) who are known both to be at high risk for breast cancer and to benefit from chemoprevention. Our hypothesis is that BCRAT has limited utility in risk estimation, and the most comprehensive model for risk estimation and clinical decision making is TC.

Methods

200 women ages 35-64 women followed in benign breast clinic were included. Risk estimations were run using BCRAT, TC version 7 (v7) and TC version 8 (v8). A Pearson's Correlation test was conducted to investigate the relationship between the TC models and the BCRAT model. A p-value < 0.05 was considered statistically significant.

Results

Analysis showed a positive moderate-strength relationship between the TC v7 10-year risk and the 5-year BCRAT risk for this population (R = 0.468, P<0.001) and a positive moderate-strength relationship between the TC v8 10-year risk and the 5-year BCRAT risk (R = 0.550, P<0.001). A TC v7 risk of 8.09% (95% confidence interval (CI): 7.42-8.75) and a TC v8 risk of 8.54% (95% CI: 7.85-9.24) corresponded to a BCRAT risk of 3%. However, much error was present when assessing consistency and correlation between the models.

A total of 36 patients were diagnosed with AH, 2 patients were diagnosed with LCIS and 7 patients were diagnosed with both AH and LCIS. 11 patients who had AH had an estimated 5-year risk per the BCRAT model of <3%. Two of these patients were pre-menopausal and African American and one was pre-menopausal and Hispanic. Of the remaining 8 patients, all were under the age of 60.

Of the 30 patients who had a BCRAT 5-year estimated risk of BC of >3% but no AH or LCIS, 12 had two first degree relatives with breast cancer and 16 had a first-degree relative with BC and at least two benign breast biopsies.

Conclusion

BCRAT is limited and caution is warranted with its use in assessing risk and for counseling around chemoprevention benefit. There is not reliable correlation between the 5 year BCRAT risk estimate and the 10 year TC risk estimate. Chemoprevention should be discussed for patients with AH, LCIS or 2+ first degree relatives with breast cancer. Further, BCRAT may underestimate risk in minority populations and others with AH. For a limited group of patients with moderate risk, dual modeling may be clinically useful in making chemopreventive recommendations.

Citation Format: Pederson HJ, Yanda C, Kline M, Stephens M, Goraya ST, Grobmyer SR, Kattan MW. Assessing utility of breast cancer risk assessment tool in comparison to Tyrer-Cuzick model for determination of breast cancer risk and implications for chemoprevention [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-09-09.

Abstract P4-06-04: Germline alterations in African-American versus Caucasian patients with triple-negative breast cancer in the era of multi-gene panel testing

Background. Triple negative breast cancer (TNBC) has been associated with a relatively high rate of germline BRCA1/2 deleterious mutations (11-20%). With use of panel testing, additional predisposition genes are being identified. Among Caucasian (CC) patients (pts), pathogenic germline variants in BRCA1/2 are mainly associated with TNBC. However, these may not fully explain the higher incidence of TNBC among African Americans (AA). Additionally, partly due to under-testing among AA, the distribution of predisposition genes for AA TNBC pts is unknown, and a greater proportion of germline alterations may be classified as a variant of uncertain significance (VUS). We hypothesized that additional clinically significant germline mutations in genes, other than in BRCA1/2, may explain the increased incidence of TNBC among AA, which may be better elucidated by panel testing.

Methods. A retrospective chart review was completed of all self-identified CC and AA TNBC pts who presented to two institutions from 10/2013 to 12/2016. A total of 596 pts were analyzed. 434 (73%) were CC and 162 (27%) were AA. Clinicopathologic features including histologic subtype, age, gender, bilateral disease and stage were examined. Patients were assessed for meeting the National Comprehensive Cancer Network (NCCN) criteria for genetic testing in TNBC, type of testing performed, and the results. The distribution of mutations in higher penetrance genes (BRCA1, BRCA2, and PALB2), pathogenic variants in other genes, and VUS in AA vs. CC were analyzed. Significance was determined using a two-tailed Fisher exact test with significance of p<0.05.

Results. 306/434 (71%) CC and 98/162 (60%) AA TNBC pts met criteria for genetic testing (p=0.023). For those who met NCCN criteria for testing, 216/306 (71%) CC and 66/98 (67%) AA TNBC pts underwent testing (p=0.61). For all pts, the average age of first diagnosis was 59.5 (SD 14) for CC vs. 62.4 (SD 12.9) for AA pts. For pts who underwent testing, regardless of meeting NCCN criteria, 18% (40/221) of CC vs.12% (8/68) of AA patients had a mutation in a higher penetrance gene (p=0.27), 1% (3/221) of CC vs. 3% (2/68) of AA had a mutation in other genes (BRIP1, Lynch genes; p=0.34), and 16% (36/221) of CC vs. 18% (12/68) of AA had a VUS (p=0.982). Of VUS, 42% (5/12) in AA vs. 19% (7/36) in CC were in higher penetrance breast cancer genes (p=0.14).

Conclusion. More CC than AA TNBC pts met criteria for genetic testing. This difference may in part be explained by the later age at diagnosis for AA given that age is a major factor in determining genetic testing. Broadening eligibility for testing in AA may help to identify more patients with an underlying genetic predisposition to TNBC. No difference was seen in the frequency of higher penetrance genes, other genes, and VUS between AA and CC pts. However, important non-BRCA genes were identified with panel testing in both AA and CC pts. In addition to broadening testing criteria for existing multi-gene panels, further genetic analysis may be necessary to explain the predisposition to TNBC in AA pts. To our knowledge, this is the first report of evaluation of predisposition genes among AA TNBC pts using germline panel testing.

Citation Format: Nizialek EA, Gopalakrishnan D, Yanda C, Abbas H, Kline M, Stephens M, Grobmyer SR, Eng C, Mitchell A, Pederson H, Vinayak S. Germline alterations in African-American versus Caucasian patients with triple-negative breast cancer in the era of multi-gene panel testing [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-06-04.

Abstract P4-10-13: Analyses of racial disparities in genetic testing and surgical management of patients with triple-negative breast cancer in the era of multigene panel testing

Background

Under-utilization of genetic counseling and testing among African-American (AA) women with breast cancer (BC) has been reported in previous studies, and there are concerns that disparities may widen with further genomic advances. Our objective was to compare AA and Caucasian (CC) patients with triple-negative breast cancer (TNBC) with regards to referral for genetic counseling, patterns of genetic testing, and patient-compliance with genetic counseling recommendations. We chose TNBC since a majority of these patients would qualify for genetic counseling ± testing. We also analyzed for differences between the two races in prevalence of deleterious BC-associated mutations, stage of BC on presentation, and surgical choices.

Methods

In this retrospective medical records-based observational study, we included all patients in our tumor registry with TNBC diagnosed between 09/01/2013 and 02/28/2017. Race, clinical characteristics and details pertaining to genetic counseling and testing were recorded. X2 test was used to compare categorical variables. A p-value < 0.05 was considered significant.

Results

477 patients -358 CC and 96 AA- with TNBC were included. Mean age was 60.3 years. 331 patients met National Comprehensive Cancer Network (NCCN) criteria for genetic counseling - of these, 85.5% had genetic consult order placed, 72.8% attended counseling, and 71.9% underwent genetic testing (multigene panel testing 55.0%, BRCA 1/2 testing 39.9%, single-site testing 2.5%, and multisite-3 testing 2.5%). Between CC and AA, no significant differences were found in the proportion of qualifying patients who had referral for genetic counseling (84.7 vs 87.7%, p=0.562), attended counseling (72.2% vs 73.7%, p=0.816), or underwent genetic testing (72.1% vs 70.1%, p=0.764). The choices of type of genetic tests were also not significantly different between the two groups (p=0.349). Though the prevalence of highly penetrant mutations in breast cancer-associated genes trended to be higher among CC than AA (14.1% vs 9.5%), this difference did not reach statistical significance (p=0.429). In our population, stage of TNBC at presentation was comparable between the two races – 80.4% of CC presented with stage I or II disease compared to 80.2% of AA (p=0.931). The two groups were also comparable with regards to the choices of breast surgery and reconstruction, as shown in the table.

  CaucasiansAfrican-Americansp-valueSurgery TypePartial Mastectomy154(47.4%)38(44.7%)0.317 Unilateral Mastectomy101(31.1%)35(41.2%) Bilateral Mastectomy70(21.5%)12(14.1%)ReconstructionYes96(56.1%)24(51.1%)0.535 No75(43.9%)23(48.9%)Reconstruction TypeImplant87(90.6%)19(79.2%)0.118 Tissue Flap9(9.4%)5(20.8%)

Conclusions

Contrary to previous reports, in this cohort of TNBC patients, we did not identify significant disparities between AA and CC in patterns of referral for genetic counseling, in patient compliance with testing or in type of testing performed. Also, no significant differences were found between the two races in choices of breast surgery or reconstruction. As a caveat, with an overall insured rate of ˜97% across our network, the uninsured population may have been under-represented by our cohort.

Citation Format: Gopalakrishnan D, Yanda C, Abbas H, Kline M, Stephens M, Grobmyer SR, Pederson HJ. Analyses of racial disparities in genetic testing and surgical management of patients with triple-negative breast cancer in the era of multigene panel testing [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-10-13.