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Study: Inherited breast cancer in Nigerian women

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Contents

At a glance             In-depth
Findings                                Resources             
Questions for your doctor  


STUDY AT A GLANCE

This study is about:

Determining the amount of breast cancer due to inherited mutations among Nigerian women.

Why is this study important?

Identifying Nigerian women who have an especially high risk of breast cancer due to an would help to focus the limited Nigerian screening resources on them.

Study findings: 

Among 1,136 Nigerian women with breast cancer who were tested for 25 breast cancer genes:

  • 167 (14.7%) had a mutation
    • 80 (7.0%) in
    • 47 (4.1%) in
    • 11 (1.0%) in
    • 5 (0.4%) in
    • 24 (2.1%) in any of 10 other breast cancer genes

Among 997 controls (Nigerian women without breast cancer):

  • 18 (1.8%) had a mutation
    • 3 (1.6%) in
    • 4 (2.2%) in
    • 1 each (0.5%) in , , , CHEK1, and GEN1
    • 5 in SLX4 and 1 in FAM175A (total of 3.3%) neither of which has been associated with an increased risk of breast cancer

What does this mean for me?

For Nigerian women or women of Nigerian decent, and have a significant effect on breast cancer incidence.  Of note, 11% of breast cancer patients in this study had a mutation in either (7.0%) or (4.1%); this is much higher than rates reported from population-based screening of African American breast cancer patients.

Questions to ask your health care provider

I am a Nigerian woman (or of Nigerian decent). Do I meet criteria for genetic counseling and testing for , or other high-risk cancer genes?

If I do not meet criteria for genetic testing for high-risk cancer genes, what are the risks and benefits of genetic counseling and testing for me?

Posted 12/5/18

References

Zheng Y, Walsh T, Gulsuner S,  et al. Inherited Breast Cancer in Nigerian Women. J Clin Oncol. 2018. (28):2820-2825.

BROCA testing panel

This article is relevant for:

Nigerian women or women of Nigerian descent who have breast cancer

This article is also relevant for:

people with breast cancer

people with metastatic or advanced cancer

people with triple negative breast cancer

people newly diagnosed with cancer

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IN-DEPTH REVIEW OF RESEARCH

Study background:

Among Nigerian women, breast cancer is frequently diagnosed at later stages and is often triple negative. Breast cancer in Nigerian women is far more frequently fatal than in Europe or the United States. Historically, breast cancer incidence in this population has been low, but recently it has been increasing.

Identification of women who are at particularly high risk of breast cancer would better target use of limited Nigerian breast cancer screening resources.  

Researchers of this study wanted to know:

1.  Among Nigerian women, what proportion of breast cancer is due to an in a breast cancer gene?

2. What breast cancer genes most frequently harbor deleterious mutations in Nigerian women?

3. What is the increased risk associated with inherited mutations in known breast cancer genes in this population?

Study design:

Participants were part of the Nigerian Breast Cancer Study.  This case-control study enrolled Nigerian patients with invasive breast cancer between March 1998 and March 2014. All participants were at least 18 years old and were included regardless of age at diagnosis, family history of breast cancer, or previous genetic testing.  Controls were recruited from hospital outpatient clinics. The study enrolled 1,136 breast cancer patients and 997 controls.

Although some participants were age 70 and older, most ranged in age from 30-59 years.  Most did not have or did not know if they had a family history of breast cancer.  Most cases were diagnosed with breast cancer ( III: 241; IV: 256; unknown: 559).  Among the patients, 133 had () and 157 did not; 846 patients did not know the hormone receptor status of their breast cancer.

Participants agreed to genetic testing using the BROCA panel of cancer genes (http://tests.labmed.washington.edu/BROCA). This panel includes both high-risk and moderate-risk breast cancer genes.  Breast cancer genes included were , , , ATR, BAP1, , , , CHEK1, , FAM175A, FANCM, GEN1, MRE11A, NBN1, , PTWEN, RAD51B, , , RECQL, RINT1, SLX4, and XRCC2.

Study findings:

Among 1,136 Nigerian women with breast cancer who were tested for mutations in 25 breast cancer genes:

  • 167 (14.7%) had a mutation
    • 80 (7%) in
    • 47 (4.1%) in
    • 11 (1.0%) in
    • 5 (0.4%) in
    • 24 (2.1%) in any of 10 other breast cancer genes

Among 997 controls (Nigerian women without breast cancer):

  • 18 (1.8%) had a mutation
    • 3 (1.6%) in
    • 4 (2.2%) in
    • 1 each (0.5%) in , , , CHEK1, and GEN1
    • 5 in SLX4 and 1 in FAM175A (total of 3.3%) neither of which has been associated with an increased risk of breast cancer.
       
  • The gene contributed most risk, because 7.0% of patients had a deleterious mutation and the increased risk associated with a mutation was extremely high (among 80 cases and 3 controls there was a 23.4-fold increase in breast cancer risk).
  • The gene contributed the second highest risk (among 47 cases and 4 controls there was a 10.3-fold increase in breast cancer risk).
  • Increased breast cancer risks were also associated with mutations in (11 cases: 0 controls) and (5 cases: 0 controls).
  • Compared with other patients, participants with mutations were significantly younger and more likely to have .
  • Compared to European women, in Nigerian women played a far more minor role in breast cancer.
  • Mutations in the FAM175A and SLX4 genes were only found in controls, which supports prior observations that mutations in these genes do not predispose to breast cancer.
  • Age at diagnosis was significantly younger for mutation carriers (42.63 years + 10.14 years) and for mutation carriers (32.8 years + 9.26 years) than for other patients.
  • The most common mutation among Nigerian breast cancer cases was pM1175R.  This is of particular historical interest because this was the first mutation identified in an African American family.

Limitations:

The primary limitation of this study was that tumor and ER/PR status was only available for a small number of participants.  This hindered the ability to document the high prevalence of in the study population. This is most likely due to the resource-limited setting of Nigeria. 

Conclusions:

Results of this study support four important conclusions: 1) Inherited and mutations have a major effect on breast cancer incidence in Nigerian women; 11% of breast cancer patients in Nigeria carry a in or . 2) Most of the well-documented prevalence of in Nigerian women remains unexplained. 3) Genetic testing in Nigerian women with breast cancer is useful only if it is comprehensive with full sequencing of all known breast cancer genes. 4) This study was an opportunity to evaluate the mutation status of breast cancer patients regardless of age at diagnosis and family history of disease or previous genetic testing.  It was designed to minimize ascertainment bias (enrolling   disproportional segments of the intended study population) to include controls from the same geographic areas as patients.  Importantly, these results revealed a very high risk for and mutation carriers with a high prevalence of mutation carriers among Nigerian breast cancer patients.

Questions To Ask Your Doctor
Questions To Ask Your Doctor

  • I am a Nigerian woman (or of Nigerian decent). Should I get genetic counseling and testing for , or other high-risk cancer genes?
  • I do not know if my relatives are from Nigeria. Should I still consider genetic counseling and testing?

Find Experts
Find Experts

The following resources can help you locate a genetics expert near you or via telehealth.

Finding genetics experts

  • The National Society of Genetic Counselors website has a search tool for finding a genetic counselor by specialty and location or via telehealth. 
  • InformedDNA is a network of board-certified genetic counselors providing this service by telephone. They can also help you find a qualified expert in your area for face-to-face genetic counseling if that is your preference. 
  • Gene-Screen is a third-party genetic counseling group that can help educate, support and order testing for patients and their families. 
  • JScreen is a national program from Emory University that provides low-cost at-home genetic counseling and testing with financial assistance available.
  • Grey Genetics provides access to genetic counselors who offer genetic counseling by telephone. 
  • The Genetic Support Foundation offers genetic counseling with board-certified genetic counselors. 

Related experts

Genetics clinics

Other ways to find experts

Updated: 07/21/2023

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