Cancer
Today there are one in three people worldwide who are affected by cancer, and
almost 60% of these people will almost certainly die. 7000 New Zealanders die
every year from this disease. It is the second largest killer next to heart
disease. Cancer does not just affect certain groups of people, it can affect
anybody and it is not just one disease, it refers to more than a hundred
diseases. Cancer is caused by carcinogens. At present, hundreds of chemicals
are known to induce cancer. Normally, the body’s cells divide in an orderly
way, allowing the body to grow and to heal after injury. Damage or mutations
that occur to the proto-oncogenes (POG) and tumour suppresser Genes (TSG) in
the genetic material (DNA and RNA) by these carcinogens bring about Cancer,
which causes cells to have less control of cell division and differentiation.
POGs lead to changed cells or transformed cells and cause excessive cell
division. Further mutations cause the cells to become immortal. These cells
continue to divide and form a ball of cells. These cells require a lot of
energy and fluids flowing to maintain the high rate of the cell division. When
these balls become too large for fluids to flow through, the middle of the ball
dies. TSG’s act as anti-proto-oncogenes, they regulate the rate of cell
division. POG’s and TSG’s constantly compete to overpower each other. These
TSG’s can be mutated and this brings about a change in the control mechanism of
cell division. Cells are stimulated to divide through a growth factor. Growth
factor molecules bind to cell membranes of cells and send a chemical message to
a receptor in the cell membrane. The receptor sends a message through the
cytoplasm to the nucleus to stimulate cell division. Sometimes when these
growth factors are absent the receptor in the cell membrane is mutated to send
out the message to the nucleus. Cells are also stimulated to divide through the
two proteins, cyclins and cyclin-dependent kinases. When these two join
together, this stimulates cell division. These proteins act on the growth
inhibitor proteins P53 and PRP, which are growth inhibitor proteins. Tumours
may be malignant, spreading or benign, non-spreading. Malignant tumours are
aggressive, invasive, and mobile. They invade healthy tissue and continue to divide.
The original cancer is called the primary tumour. If the tumour is malignant,
the disease may develop in other parts of the body where secondary tumours may
form. This is known as metastasis. Cancer causes illness through local growth,
spread to distant organs, and overall effects of the disease on the individual.
Treatments of cancer vary. Tumours may be surgically removed if they have not
metastasised. Other methods are usually used if the tumour has metastasised.
For chemotherapy drugs are used to kill cancerous cells as they divide.
Radiotherapy is another standard way of treating cancer, ionising radiation
aimed at the tumour will prevent the cells from dividing further. So what makes
cancer more special than other diseases? The answer is that there is no cure
and scientists are not optimistic of finding one in the near future. Today
people are far more knowledgeable about cancer and how it may be avoided than
10 years ago. It has now been found that as many as 80% of all cancers may be
avoidable. The most common types of cancer in New Zealand are female breast
(14%), male prostate (14%), trachea, bronchus, and lung (12%) and colon (11%)
Given that such a large proportion of cancers may be avoidable, why isn’t there
a reduction in cancer incidence? This may be because our educational programs
are not appropriate and perhaps even due to people’s ignorance. Female breast
cancer and male prostate cancer can almost always be cured if detected and
treated in time. For the early detection of female breast cancer appropriate
programs such as monthly mammogram and breast self-tests have been introduced.
But I believe that male prostate cancer has not been addressed enough (more?).
80% of lung cancers have been found to be caused by smoking. Today billions of
dollars are spent throughout the world on cancer especially in developed
countries of the western world where a lot of money is freely available. Most
of this research is carried out by private organisations and therefore ethnic
minorities appeal to be included in their research. Dietary factors underlie as
many as 35% of all cancers. Of this 35%, almost 80% of the patients are colon
cancer patients. The government has taken on a major preventative scheme,
introducing the 5+a day dietary standards to improve the intake of more fruits
and vegetables into people’s daily diets. This aims at reducing bowel cancer in
New Zealand, which will no doubt save lives. For these reasons, cancer is a
contemporary issue. Biological, ethical and social issues surround it. It also
seems that a lot has been done to prevent it but there is so much further to
go, and this would ultimately reduce the number of lives that the cancer
claims.
References
http://cancernet.nci.nih.gov/
http://www.fhcrc.org/
http://www.cancerresearch.org/