14 July 2019
A study recently published in the journal Cancer* reports on disparities in triple negative breast cancer (TNBC). The researchers used the US cancer statistics database, and compared differences between TNBC and other breast cancer subtypes focusing on age, race / ethnicity, and stage at diagnosis.
Between 2010 and 2014, approximately 1.15 million breast cancer cases were identified in the database. The mean age at diagnosis was 61.8, and 75% of patients were non-Hispanic white (NHW). 27.7% were diagnosed at stage III and 5% were diagnosed at stage IV.
TNBC accounted for 8.4% of all breast cancer cases, but accounted for 21.4% of cases in non-Hispanic Black (NHB) women. Women diagnosed with TNBC had a lower mean age at diagnosis versus non-TNBC (59.3 versus 62.1). NHB women accounted for 11.8% of the study population, but 15.3% of TNBC cases. Women diagnosed with TNBC were also more likely to be younger than age 40 and diagnosed at Stage III or IV compared to those with other cancer subtypes. After controlling for late-stage diagnosis and age, NHB women had approximately twice the likelihood of diagnosis with TNBC compared with NHW women.
The researchers noted that their study validated previous literature, and had the advantage of being geographically very broad. Not discussed in this paper is the relationship of TNBC with genetic mutations, specifically mutations in the BRCA1 gene. Among patients with breast cancer, those who carry deleterious BRCA1 mutations are more likely to have TNBC versus BRCA2 carriers or non-carriers, and a diagnosis of TNBC should prompt genetic testing.
This study and others like it point to the need for more research on TNBC, and on breast cancer in black women. Dr. Lisa Newman, a breast surgical oncologist at Cornell, has published extensively on this topic. In this brief video, she notes that socioeconomic factors account for some of the disparities associated with breast cancer outcomes in black women. However, she also notes that there appears to be biologic differences between TNBC in black versus white women, which may also at least in part account for later stage at diagnosis and poorer prognosis.
*If you are not able to access the full study and would like a copy, please email me: contact at drattai dot com