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0:05
This is a timeline of the
breast microbiome research,
and from the very beginning
it was basically focused
on the microbial communities
and human breast milk,
since that was the first source
of immunoglobulins to the infant
that stimulated
the immune system
of the infant basically,
and it was found
that it did have
some beneficial microbes
in it and around 2014,
it was found that
microbial composition of
the breast milk was very
similar to nipple aspirate fluid
of women even after weening.
Initially, it was thought
that it would be because
there is an orifice and
opening to the environment,
it must be a
environmental exchange
rather than an intrinsic
component of the milk,
but with further studies
it was found that
it's not really an
environmental exchange,
but it depended on
the maternal diet
and it was actually
a component of the
breast milk as well
as nipple aspirate fluids.
1:01
Coming to microbiome and its
relation to breast cancer
risk,impaired microbiota in
the gut as well as
the local breast
microbiota can lead to
downstream signaling
pathways which
can lead to carcinogenesis.
In 2014, Urbaniak and group,
they screened breast tissue from
multiple sites around
the breast of women
18-90 years old in two different
cohorts of Canadian
and Irish woman,
and both cohorts
harbored rich microbial
communities independent
of the lactation status,
and in a successive study,
they compared the microbiota of
the normal breast to
the breast tumors,
and this was really
the beginning of
breast cancer
microbiota association.
In 2016, Lee et al
characterized the nipple
aspirate fluid of
healthy woman and
breast cancer survivors
and they did find
significant differences.
Another study in 2016
had characterized
the microbiota of benign and
malignant breast tumors,
and within a few years
multiple studies were
published that descriptively
characterized the breast cancer
associated breast microbiome and
gut microbiome and few
identified sub-type specific
signatures as well.
So breast cancer has
different subtypes.
It's really not a
single disease,
it's a category of diseases.
We have hormone receptor
positive breast cancers,
ER/PR triple negative
breast cancers
as well as HER2
enriched breast cancer.
And studies have found
that different subtypes of
breast cancer is associated
with different
microbial signatures,
and hormone regulation,
obesity and
microbial metabolites were
postulated to be responsible for
microbiome-breast
cancer association
and microbiome induced
immunometabolism and
mechanistic studies
gained importance post 2018.
