If you recall we spent week five of
the course discussing the different treatments available for those who have
cancer. During the week, we discussed the three most common methods of
treatment, those being: surgical oncology, radiation therapy, and medical oncology.
Surgical oncology mainly takes place as a treatment in the form of a resection
of a solid tumor with wide margins to ensure complete removal. Radiation
oncology uses x-rays and carbon ions to directly damage DNA of the cancer cells
in hopes the damage will prevent continued growth. Lastly, we discussed medical
oncology, wherein we discussed chemotherapy. When we discuss personalized
medicine we are generally referring to changing the way in which we use medical
oncology.
Today if you are in the unfortunate
circumstance that you have cancer, the way in which you are treated for that
cancer doesn’t have a lot to do with who you are. It will vary depending on
what type of cancer you have, yes, but nothing to do with you as a person. The
doctor will give you the same treatment to those who have the same cancer, at
the same stage as you. This is due to
the precedents within the “standard of care” which involves finding and
administering the best treatment for the general population. For example,
pre-emptive measures for breast cancer include self-exams until age 40 when
mammograms become the standard and, if diagnosed, surgical oncology and medical
oncology (chemotherapy) are recommended. In many cases this standard of care
may be the safest, most sensible option. However, while you may have the same
type of cancer as the other patient in the waiting room, you are not the same
person as them, and this is what personalized medicine tries to focus on by
incorporating a person’s genetic makeup.
At its core, personalized medicine
is an approach that emphasizes the ways in which your disease risks are unique
and different, based on the predispositions written into your genome at birth.
Its emphasis is then transcribed into an action of prevention, diagnosis, and
treatment that is very specifically designed for you. Because of the human
genome project we have identified every genome in the human sequence. This and
other advancements have made it so anyone can have their personal genomes
scanned and fully sequenced. These genetic tests could lead to successful
medical oncologic treatments (like drugs) rather than surgery. For example,
liver can be BRAF positive and if this is identified then you could take
sorafenib, an FDA approved drug by disabling the BRAF kinase domain. It
does this by preventing ATP from binding and, hence, locking the enzyme in its
active form. In a different case, cystic fibrosis patients have a mutation in
the CFTR gene. This causes the over secretion of mucus, impeding the lungs and
pancreas, leading to labored breathing and the pancreas’s inability to absorb
what it needs from food. Thanks to studies done on the CFTR gene, researchers
have found a mutation that’s found in 4% of cystic fibrosis patients. The mutation
is caused by the amino acid glycine (at 551) being replaced
with an aspartic acid. Specifically for G551D, the protein is brought to the
epithelial cell surface (the correct destination), but protein cannot transport
chloride through the ion channel. Ivacaftor promotes the transport of chloride
through the ion channel by binding to the channel, which increases the chance
that the ion channel remains open.
In the method of prevention, I
think that the prime example stems from breast cancer. Those who are carriers
of a BRCA1 mutation are at a 65% risk of breast cancer and 39% of ovarian
cancer. Generally, it is not until after they find an anomaly in mammogram that
they test for the BRCA1 mutation. However, with the ease of testing now, if
testing for the BRCA1 mutation became apart of one’s first physical it could
warrant starting mammograms before the age of 40 and making them more frequent
than once a year. This would help to catch the breast lump as a carcinoma in
situ, providing a much better outcome for the patient in that he or she might
not need chemotherapy.
In the case of cancer, great
strides have come from the incorporation of genetics into medicine. We have
seen a couple cases in which genetic testing could be, and has been, used
helped to improve the outcomes of those who have taken the advantages of
personalized medicine. One of its pitfalls is that in a recent study by GfK (a
global research firm), only 4% of those questioned knew what Personalized medicine
was based on the definition “medicine based on genomic makeup”. In addition,
those that do know about its possible positives want to see evidence before you’re
willing to move away from the tried and true methods of treating cancer.
References:
McMullan, Dawn. "What Is Personalized Medicine?" Genome Spring
2014 (2014): 34-39. Web. 1 June 2014.
Morton, Carol C. "Dana-Farber/Harvard Cancer Center: The
Future of BRAF Inhibitors." The Future of BRAF Inhibitors.
Harvard University, n.d. Web. 1 June 2014.
Verma, Mukesh. "Personalized Medicine and Cancer." Journal
of Personalized Medicine 2.1 (2012): 1-14. Web.
