Abstract P1-10-05: Analysis of genetic mutation in ethnically diverse population with Breast and ovarian cancer: Single institution experience
Authors: Aggarwal S , Chu C , Ngumi M 
Published: May 2019

Only 5-10% of all breast and ovarian cancers have been attributed to inherited mutation. In unselected breast cancer patients, prevalence of germline BRCA 1 & 2 is about 2%. In Ashkenazi Jewish population the prevalence is estimated to be 11.7%. The rate of mutations in other populations has not been well characterized. The purpose of this study is to identify and characterize the risk of genetic mutations in an ethnically diverse population referred for genetic testing according to NCCN guidelines.

Method:

In this single institution retrospective study, we analyzed 782 patients referred for genetic testing between 2009-2018. Information regarding reason for referral, ethnicity, cancer history and results of genetic mutation using multigene panels were collected.

Results:

Reasons for referral were:

· Family History of cancer (142; 18.6%),

· Breast cancer diagnosed at early age (207; 26.4%),

· Triple negative breast cancer (12 ;53%

· Ovarian cancer (61; 7.8%)

· Multiple cancer (32; 4.09%)

· Known BRCA 1 or 2 mutation (51;6.5%)

· Known other mutation (9;1.15%)

· Family h/o cancer but not diagnosed with cancer (268)

Ethnic distribution:

· 328 Hispanic (41.94%)

· 177 Caucasian (22.6%),

· 27 Chinese, (3.4%)

· 52 Vietnamese (6.6%)

· 86 other- Asian (11%)

· 32 Middle eastern (4.1%),

· 14 South Asian (1.8%)

· 35 African American (4.5%)

· 8 Ashkenazi Jewish (1%)

· 19 Mixed Hispanic (2.1%)

Genetic testing was done in 545 /782 patients.

Deleterious Mutation detected: 88 patients (16.5% of tested)

· BRCA 1: 32(5.8%)

· BRCA 2:28 (5.14%)

· MSH2:5(0.9%)

· p53:39 (0.5%)

· PLB2:3 (0.38%)

· MUTYH:3 (0.38%)

· CDH1 :2 (0.26%)

· PMS2: 2 ( 0.26%)

· ATM: 1(0.13%)

· CCKn2A: 1(0.13%)

· CHEK 2: 1(0.13)

· MET:1(0.13%)

· MSH6:1 (0.13%)

· RAD50 :1(0.13%)

· RET1;1(0.13%)

BRCA1/BRCA2 mutation: 60

Mutation in BRCA 1/ 2 distribution by ethnicity:

· Hispanic (28; 8.54 %),

· Chinese (4;14.8%)

· Vietnamese (4; 7.7%)

· other Asian (12;13.9%)

· African American (3, 8.5, %)

· South Asian (0 %)

· Caucasian (8; 4.5 %)

· All Asian (20/165: 12.1%)

Mutation in other gene by Ethnicity: total 26

Hispanic (16, 4.5%), Caucasian: (3, 1.7%) Asian other than Chinese and Vietnamese (4, 4.65%)

Mutation in Breast cancer: 333 Breast cancer patients tested, 39 patients (11.17%) were found to have mutations.

10/32 triple negative (31%) 4/49 her2neu positive patients (8.1%) and 15/252 (5.9%) ER+ patients found to have mutations.

17/39 breast cancer patients with mutation had prophylactic BSO.

Mutation in BRCA 1& 2 by reason for referral:

Known family h/o of BRCA1 or 2 mutations (18; 39.5%)

Early age of cancer (10, 7.4%)

Cancer with positive family history (17, 8.2%)

Triple negative (2, 16%).

Variant of Unknown significance (VUS): 140 patients (25 %)

VUS in BRCA 2 were most common. VUS were found in 17% of Hispanic and African American patients.

No significant difference in PFS and OS was found in patient with mutation and without mutation

Conclusion:

We found much higher rates (16.5%) than previously reported mutation detection in this very highly diverse patient population.

Rate of BRCA 1&2 mutation was 8.55% in Hispanic and 12.1% in Asian patients compared with 4.5% in Caucasian patient when selected for high risk factors.

We Also noted very high rate of VUS especially in Hispanic and African American patients.

Citation Format: Aggarwal S, Chu C, Ngumi M. Analysis of genetic mutation in ethnically diverse population with Breast and ovarian cancer: Single institution experience [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P1-10-05.