The Ethnic Profile of Triple-Negative Breast Cancer

more likely to relapse than other breast cancer sub-types [13, 14]. Thus, universal negativism about triple negative breast cancer may not be justified. The profile of breast cancer in terms of age of onset and age distribution of molecular subgroups of the disease varies across the major ethnic subgroups, with Asian populations appearing demographically distinct. It is clear that incidence of breast cancer is much lower in Asian as compared to other ethnic groups. An analysis of data from the Surveillence, Epidemiology, and End Results (SEER) database and Osaka Cancer Registry (1978–97) showed overall ageadjusted incidence rates per 100,000 woman-years were highest in Whites (in SEER) (87.6), followed by Blacks (in SEER) (80.0) and lowest in Osaka (21.8). The Japanese population in this study was distinct in lacking the preponderance of postmenopausal breast cancer seen in both White and Black populations [15]. This preponderance of postmenopausal breast cancer in White and Black populations has been attributed to a complex interplay of life style factors [16] and access to healthcare, in particular breast screening [17]. It is not clear to what extent the demographics of Black Americans reflect those in other Black populations and indeed how representative the Japanese population is of other Asian ethnic subgroups. Much has been written about the triple negative breast cancer in Western populations where it accounts for approximately 10–15% of all breast cancer cases [4, 18]. It has been consistently reported that the triple negative phenotype is proportionally more common in Black populations including women with Nigerian ancestry (58% in one study) [19] and within African populations in the US (20–21%) [18, 20], with a striking preponderance for pre-menopausal women. This demographic may be in part due to underlying host (germ-line) genetic factors, including inherited polymorphisms. However, a case-control study of African American and White women (the Carolina Breast Cancer Study) showed that basal cancer cases were associated with exposure of a set of ‘basal breast cancer risk factors’, namely multiple live births which did not The article in this issue of ONKOLOGIE by Tian et al. [1] describing a series of triple negative breast cancers in a population of Chinese women joins the growing literature describing this sub-class of breast cancer within specific ethnic groupings. The immunohistochemical phenotype of oestrogen receptor (ER), progesterone receptor (PgR) and the HER-2 receptor negative breast cancer has been apparent for many years but its existence was highlighted by the expression RNA microarray work of Perou et al. and others that demonstrated a molecularly distinct group of breast cancers characterized by under expression of these three receptors, up-regulation of components of proliferation pathways and an expression profile that clustered with that of breast cancers arising in BRCA 1 mutation carriers [2, 3]. The triple negative subgroup overlaps with the morphologically distinct group of ‘basal-like breast cancers’, characterized by high mitotic count, central necrosis, frequent apoptotic cells, a stromal lymphocytic response and expression of myoepithelial markers (cytokeratins 5, 6, 14 and 17) [4, 5]. The triple negative subgroup of breast cancers is not homogeneous in terms of morphology, as it includes cancers with metaplastic, atypical or typical medullary and adenoid cystic appearance [4–7]. Clinically, triple negative cancers are characterized by high probability of systemic disease, and in particular development of lung and brain metastases [8, 9]. However, there is again hetererogeneity as some subgroups, for example adenoid cystic carcinoma of the breast, are associated with an excellent prognosis [10]. Despite their aggressive natural history, triple negative breast cancers are more likely to achieve a complete pathological response to pre-operative chemotherapy (pCR) than other breast cancer types [11], and it appears that these patients with marked chemosensitivity have a relatively good chance of long-term survival [12]. Furthermore, although most studies demonstrate an association between the triple negative phenotype and poor outcome, some studies suggest that this negative association loses significance after 10 years, suggesting that patients that survive the first few years are no