The development of cancer is similar to
the gradual changes Anakin Skywalker
under goes as he is lured under the
influence of Emperor Palpatine to become
the Sith Lord Darth Vader turning his
back on the Jedi Order to fight against
the very thing he once served. In the
same way cancer cells were once our own
healthy cells that have become corrupted
and are now causing damage to the very
body they were once part of.
In our bodies healthy cells peacefully
coexist and often help one another carry
out their essential functions. We can
think of these healthy cells as a young
Anakin Skywalker who did whatever he
could to help the people of Naboo,
however if these healthy cells
experience high levels of stress or
are infected by certain bacteria or viruses
they can become altered, causing them to
become cancerous. This was seen in Star
Wars when Anakin started to receive
disturbing visions of his loved ones,
which led him to abandon his training
and returned to Tatooine in search of
his mother. The anger he feels after his
mother's passing,
combined with the dark influences of
Palpatine starts Anakin's journey to
becoming lord Vader. This corruption by
Palpatine is akin to a viral infection
taking over the mind of Anakin, in the
same way that a virus infects our cells
and hijacks the cellular machinery.
Palpatine is an oncovirus, a virus
that causes cancer and in the same way
that Palpatine, despite being the Sith Lord
Darth Sidious, hides in plain sight as the
Chancellor of the Republic
these oncoviruses, which can include
things like Epstein-Barr and Hepatitis B,
tend to not cause diseases in their host
but can lie dormant and introduce new
genetic material into host cells that
cause uncontrolled growth. Cancer is
actually a name for the collection of
diseases where cells behave abnormally
but it is characterised by the
uncontrolled growth and division of our
own cells and ultimately manages to
evade our immune system and promotes an
environment where the tumour cells can
flourish. In Star Wars terms this is
similar to Palpatine slowly corrupting
Anakin gradually, leading him to the dark
side to ultimately lead the Empire in
their fight against the Jedi across the
galaxy.
Vader represents a cancerous cell, the
Empire a growing tumor and the Jedi Order
is the immune system attempting to keep
that evil at bay. The Jedi, especially
Grand Master Yoda, were
aware of the potential of Anakin to
become evil, however, they became
powerless to prevent him from turning
against the order, due to the deceit of
Palpatine and were too late in trying to
eliminate the threat. In the same way, our
immune system, although it can initially
recognise cancerous cells becomes
ineffective in defending us as the
cancerous cells develop ways to evade the immune system. This increase in the power
of the dark side is similar to a
sequence known as the three E's of the immune
response to cancer, standing for
Elimination, Equilibrium and Escape.
During the elimination phase the immune
system is on top, in the same way that at
the start of Star Wars the Jedi have
suppressed the Sith. The equilibrium stage
is where cells start to change and mutate
to try and fight ways to evade the
immune system but the tumour is not
actually growing. In a similar way that
Palpatine starts to manipulate Anakin,
luring him towards the dark side but he
has not yet turned into Vader. Finally, the
escape stage is where the tumour cells
gain dominance over the immune system
and the tumour starts to grow, which is when
Anakin's transformation to Vader is
complete.
So, how does the immune system defend
against cancer? Well, cancerous cells
present abnormal proteins on their
surface, which tells the immune system
that something is wrong. When the immune
system detects a cancerous cell it
deploys the body's main anti-cancer
defenders, including macrophages shown
here as Chewie, natural killer cells
represented by Mace Windu and CD8+
T-lymphocytes depicted as
Obi-Wan kenobi. In Star Wars, as Anakin
transitions to become Darth Vader, Windu
senses a huge disturbance in the force
and tries to prevent Anakin from
crossing to the dark side but he is
ultimately unsuccessful. At the same time, R2D2, who represents a dendritic cell
hurries back to the rebel base to
present information about Palpatine
and Vader's future plans to rule the galaxy
to his trusted friend Leia and Luke, who
represents CD4+ and CD8+ T cells.
Luke and Leia start to form their own
rebel army in preparation for the battle
against the Empire.
These abnormal proteins are presented by
a molecule called MHC class 1, which acts as a sort of self-identifier tag,
allowing cells of the immune system to
see what is going on inside the cell.
Cancer cells are clever and can reduce
the expression of these self-identifier
tags to a level where the CD8+ T-lymphocytes are unable to see the threat,
however, if there are no MHC class 1
presented on the surface, then the
natural killer cells would recognise the
cells as abnormal and kill them as Windu
finally does, when he attempts to
intervene to prevent Anakin's transition.
So how is cancer treated? There are a
wide range of options including surgery
to remove the tumour, chemotherapy and
radiotherapy to destroy the cancerous
cells but these are really like using a
sledgehammer to crack a nut, as a side
effects can be pretty horrific.
Scientists have been working to develop
more targeted treatments, including
cancer vaccines, which rather than
prevent cancer act to stimulate the
immune system and help ramp up the fight.
You can think of this as the Rebel Alliance
growing in strength as they learn more
and more about the Empire and how to
defeat it. Another promising option is
called T-cell therapy, where the T-cells
that are able to recognise cancer can be
isolated from the blood and altered to
make them better at destroying cancerous
cells. We can think of this as the
production of clone troopers with
specific knowledge of the threat the
Empire poses being trained on Kamino to
fight more effectively and then being
led into battle by Luke Skywalker. There
is hope this approach could, one day, be a
universal therapy for cancer. Finally,
checkpoint inhibitor therapy is another
promising option which involved blocking
the signaling pathways the cancer cells
used to evade the immune system. At the
end of Rogue One, the rebels on the
surfaces Scariff are trying to
transmit the plans for the Death Star to
the rebel fleet, but the signal is
being blocked by the Imperial shield
gate.
This shield gate is similar to the
suppressive environment that a
tumour creates for itself, but once
destroyed the plans could be transmitted,
giving the Rebels new hope in their
fight against the cancerous Empire.
Despite the Rebel's best efforts, the Empire always seems to find a way to survive
and establishes themselves on another
planet where the dark powers continue to
grow once again in secret. Many cancers
develop the ability to travel to other
parts of the body, which is what we call
metastasis. In order for the new tumour to
be destroyed the series of events
covered so far have to be repeated, but
the cancer is clever, it learns from its
past encounters and operates differently
than before. This makes it harder, not
only for the immune system to
effectively destroy metastasised tumour
formations in our body but the same is
true of anti-cancer drugs as well, which
is why patients with metastasised
cancers typically have poorer outcomes.
In this episode of Immunology Wars we
have looked at how cells can become
cancerous and some of the ways our
bodies can defend us against the threat,
as well as some of the treatments that are
currently available. We hope you've
enjoyed this episode of Immunology Wars.
Join us next time when we will be
discussing vaccinations in "A New Hope".
