The term "triple-negative breast cancers" first appeared in medical
literature in 2006 and ever since it has been steadily appearing in several
publications, a move that indicates its growing popularity among the
Triple-negative breast cancers have been
defined as tumors that are devoid of the expression of estrogen receptor (ER),
progesterone receptor (PR), and HER2.
be noted that 12-17% of women with breast cancer have - triple
-negative breast cancer.
category of breast cancer includes other
molecular subtypes of breast cancers such as:
• Claudin-low tumors
which have cells with stem-cell like
• Interferon-rich subgroup
with better prognosis than the
triple-negative breast cancers
with a disproportionate high numbers of stromal and
Basal-like Breast Cancers
breast cancers are categorized as one of
intrinsic subgroups of breast cancer.
their name, it is now known that the origin of these cancer cells is from the luminal cells of the
glandular tissue of the breasts and not from the basal cells.
features include -absence or reduced expression of ER, absence of HER2 over
expression, and also the expression of genes that are usually found in normal
have shown that basal-like breast cancers are more likely not to spread to the
lymph nodes and hence be node-negative
compared to other breast cancers.
is a breast cancer susceptibility gene and a mutation in this gene can
be found in certain forms of hereditary breast cancers. A link has been
established between the BRCA1 pathway and basal-like breast cancers.
majority of tumors showing BRCA1
(especially those found in women who are diagnosed before 50
years) have phenotypic features similar to those of nonhereditary basal-like cancers.
could indicate that the BRCA1 pathway may be dysfunctional in nonhereditary
and basal-like breast cancers are a collection of different diseases.
and basal-like tumors have a high histological grade
• They account
for about 15% of all invasive breast cancers.
• Both these
cancers are seen to occur more frequently in young Black and Hispanic women in
comparison to young women of other racial or ethnic groups.
• More than 75% of tumors with breast-cancer
susceptibility gene (BRCA1) mutations have a triple-negative phenotype or a
basal-like phenotype or both.
• Cancerous cells
from both these cancers display cell-surface markers that resemble
breast-cancer stem cells
• In comparison
to other types of breast cancers both triple-negative and basal-like breast
cancers have greater chances of metastasizing to the viscera (especially to the
lungs and brain) but not likely to the bone
• Both these
cancers show a correlation between the size of the primary tumor and prognosis
is the mainstay of treatment
a combination of genetic, environmental and societal factors that contribute to
a person's susceptibility to develop breast cancer.
factors for triple-negative and basal-like tumors include the following:
• High hip-waist
• Early menarche
• High body mass
• Reduced breast
breast cancers exhibit features of both
triple-negative breast cancers and basal-like breast cancers.
majority of triple-negative breast cancers (approximately 80%) are basal-like
breast cancers, and the majority of basal-like cancers are triple-negative
breast cancers. Hence there are claims that they are effectively the same.
clinical, microarray, and immune histochemical studies show that this is not
true and that they have their own distinct features. Seen from the genetic
perspective too, both triple-negative and basal-like breast cancers are greatly
it must be noted that there is no internationally- consented definition for
these two subgroups of breast cancers.
Many studies have
indicated that triple-negative and basal-like
breast cancers are linked to poor prognosis.
status is useful in predicting the prognosis of invasive breast cancer. ER
positivity predicts the person's response to endocrine therapy. Being negative
for ER, progesterone receptor (PR), and HER2, is linked to aggressive
histology, poor prognosis, and unresponsiveness to the routine endocrine
therapies, shorter survival, and BRCA1-related breast cancer.
triple-negative tumors have poor
appears to be a sharp dip in survival during the first 3 to 5 years after
decade relapse occurs-- more so among patients with ER-positive cancers than
those with ER-negative cancers.
group triple-negative and basal-like breast cancers display aggressive clinical
behavior, but there exists subgroups of these cancers that are very sensitive
to chemotherapy. As expected
subgroups show good prognosis, when subjected to chemotherapy.
The need of the hour is to identify triple
negative tumors that are sensitive to specific or a combination of chemotherapy
agents. The role of target therapy
in containing triple-negative breast cancer is currently being researched.