Content
The Cell
Cells have been around for at least 3.5 billion years. It is believed that eukaryotic cells evolved from prokaryotic cells. There are different theories on how the first cells came to be, from being carried to Earth by meteorites, to being created at deep sea vents, to being synthesized by lightning in a reducing atmosphere.13
There are two categories of biological cells, prokaryotic and eukaryotic. Prokaryotic cells are unicellular, and unlike eukaryotic cells, they do not have a nucleus or membrane-like organelles. All cells, except red blood cells, contain DNA. The majority of its DNA, which is usually one circular strand, is found in the nucleoid. Bacteria and archaea are prokaryotic cells. Typically, prokaryotic cells are much smaller and simpler than eukaryotic cells.
Unlike prokaryotic cells, eukaryotic cells have different compartments with specialized functions. Eukaryotic cells contain a nucleus with the DNA information needed to carry out the cell’s functions. There are other membrane bound organelles within the cell, like mitochondria and lysosomes, for example. While all cells replicate, prokaryotic cells replicate by binary fission, while eukaryotic cells replicate by mitosis or meiosis. It is eukaryotic cells that I will concentrate on in this unit.
The Virus
A virus is a particle that reproduces by attaching itself to a host cell. Under guidance of the viral genome—either DNA or RNA—the virus uses the host cell to make more viruses. Viruses need a host cell because without it, they cannot reproduce. This is the reason they are considered non-living. They do use the same genetic code as living cells, however. This allows them to reprogram the host cell, allowing for the making of more viruses.
Viruses are small, much smaller than bacteria or our regular cells. They are tiny packages of nucleic acid and protein. The DNA or RNA is found inside a protein shell, called a capsid. Some viruses have a membrane called the envelope. They are extremely diverse and have different kinds of genomes, and infect different kinds of hosts. When viruses attach themselves to the host cells, they reprogram the cell to become a virus-making cell. There are about 1031 viruses on earth at any given time but most of these viruses are found in oceans where they attack bacteria and other microbes.14
The Viral Infection
A viral infection means that many viruses are using the body’s cells to make copies of themselves. The viral life cycle is the process in which this occurs. Generally, the virus attaches itself to the cell; after that, the virus enters the cell. Once the virus is inside the cell, the DNA or RNA is copied and its genes make viral proteins. New viral particles are assembled from the genome copies and viral proteins. These new viral particles exit the cell and are ready to infect other cells and continue the process. Human papillomavirus (HPV) is the most common sexually-transmitted infection in the US.15
In 1983 and 1984 in Germany, physician Harald zur Hausen found that two HPV strains, HPV-16 and HPV-18, caused cervical cancer in women. By identifying this, they were able to make a vaccine that would target these strains. Harald zur Hausen started his research on HPV after reviewing medical reports that discussed cases of HPV genital warts that progressed to cervical cancer in female patients, and in 1976, he published his hypothesis that HPV caused cervical cancer in the article, "Condylomata Acuminata and Human Genital Cancer”.16
This is one of the reasons that Pap smear tests are so important. The Pap smear was named after Georgios Papanikolaou, the doctor who determined that this was an effective way to test for cervical cancer. The Pap smear test which was developed in 1928 is a screening that is able to test the woman’s cervix and detect abnormal cells taken from the lining. Most of the time, the test is able to detect any change that occurs in the cells of the cervix. Most cervical cancers develop over a long period of time, therefore having regular check-ups is key to prevention. The test will be able to determine if there is a change in the cervix before the cancer even forms. According to the American Cancer Society, changes in the cervix are often caused by the human papillomavirus.17
The Cancer
According to the Cancer Treatment Centers of America, we have about 40 trillion cells and those cells constantly go through the process of mitosis in order to duplicate and form new cells. Mitosis is a process where cells divide and produce more cells that are genetically identical to themselves. Since cells wear out, they need to keep reproducing themselves. Mitosis begins with a mother cell which divides and produces two new identical cells, daughter cells. This process replaces old cells with new ones. Mitosis splits its chromosomes in a series of steps.
There are four basic phases in mitosis: prophase, metaphase, anaphase, and telophase. Cytokinesis, the step where dividing the cell to make the two new daughter cells, begins in anaphase or telophase. These phases occur in sequential order. Right before a cell begins mitosis, the cell is in interphase and has copied its DNA. The cell has also made a copy of its centrosome, making it a total of two. In early prophase, the mitotic spindle begins to form; the spindle’s job is to organize the chromosomes during mitosis, and the nucleolus disappears. In late prophase, the spindle begins to capture and organize the chromosomes. Then comes metaphase, here the spindle has captured and lined up all the chromosomes in the middle of the cell and is ready for them to divide. During anaphase the sister chromatids separate from each other and are pulled toward opposite ends of the cell. In telophase the cell is nearly done dividing. Remember, cytokinesis takes place around anaphase or telophase, so the two cells are now beginning to divide.18
Not all cells divide at the same rate. Cells in the brain do not divide very fast, on the contrary, cells in the lung, gut, and bone-marrow have more divisions during mitosis than normal. Sometimes, something in the cell division goes wrong and cells begin to grow out of control. Cancer cells proliferate even more rapidly, while a normal cell would eventually stop proliferating.19 Therefore, when we speak of cervical cancer, it is this out of control cell division in the cervix. They are heterogeneous cells that do not stay contained. When those cells continue to grow, they accumulate and form a mass called a tumor. Cancer is graded according to its stage.
The Tumor, Node and Metastases (TNM) is a staging system that classifies tumors found in the body. The T is used on a scale of 0 to 4. A 0 indicates that the tumor has not invaded the local environment and a 4 means that a tumor has spread into another organ.
While most cells know their boundaries, cancer cells do not. Cancer cells can spread throughout the body through the lymphatic system. The lymphatic system helps rid the body of toxins, waste and other unwanted materials. The primary function of the lymphatic system is to carry lymph, a fluid containing white blood cells, which make T-cells, throughout the body. Dead cells are collected in the lymph. Lymph nodes are found throughout the body and contain many cells, in particular white blood cells. They act as filters for immune activity. In the lymph nodes, cells help fight bacteria and viruses. The tonsils, adenoids, spleen, and thymus are all part of the lymphatic system.20 N0 indicates that no tumor cells have entered the local lymph nodes, whereas N4 indicates excessive involvement.21
If the tumor spreads to a different site from where it originated, it is said to have metastasized. This is a sign that the tumor is in advanced stages. The letter M represents how much the tumor has metastasized. M0 meaning no metastasis and M1 indicating that metastasis is present.
The Vaccine
In the early twenty first century, pharmaceutical companies Merck & Co. and GlaxoSmithKline created HPV vaccines protecting against HPV-16 and HPV-18. These vaccines have reduced the number of HPV infections by fifty-six percent in the US.22 There are two vaccines, Gardasil and Cervarix. While Gardasil protects against four strains of the human papillomavirus- HPV 6, 11, 16, and 18, Cervarix protects against two, HPV 16 and 18. HPV 6 and 11 cause 90 percent of all genital warts. HPV 16 and 18 cause about 70 percent of all cervical cancers and are associated with about 80 percent of anal cancers.23
In the United States, HPV vaccination rates have been strongly and inversely correlated with cervical cancer mortality rates and median income. Because cervical screening coverage is inversely associated with poverty and deprivation, ensuring equitable HPV vaccine delivery and high coverage in populations that are less likely to have opportunities for cervical screening as adults remains a priority.24
Global Perspective
Globally, cervical cancer is the third most common cancer among women. There are an estimated 529,000 new cases and 275,000 in the year 2008. More than 85% of the cervical cancer cases occur in developing countries. Also, 88% of the cervical cancer deaths that occur globally occur in developing countries.25 Although there is a vaccine, the cost of it is too much for many women in these developing countries to afford.
Not only is cervical cancer represented disproportionately among women on a global scale, but there is a large disparity here within the United States. The incident rate of cervical cancer is about twice as high among Latina and African-American women living in the U.S. than among white women. Furthermore, the death rate for Latinas and African-American women who die of cervical cancer is also 50% more than their white counterparts.26 According to the Association of Reproductive Health Professionals, these disparities are thought to be due to low rates of Pap testing and failure to follow up with treatment after abnormal Pap testing among Latinas. Widespread poverty, which leads to decreased access to medical care, diagnosis at a later stage of disease, and unequal treatment for African American women is also an explanation given by them. I would even suggest that due to the history of negative medical practices against African Americans in this country, there is a wide distrust among the African American community and some of the medical practices in the United States.
In looking at cervical cancer from a global perspective, it is impossible to ignore the disparities that exist in cervical cancer rates among women of different regions. As close to home as our southern border, statistics show that in the border region of Texas cervical rates are 30 percent higher than the national average. According to NPR, “while methods of preventing cervical cancer in the United States continue to advance and shift, disparities persist. Women with the fewest years of schooling are the least likely to be screened. And African-American and Hispanic women are disproportionately represented among those who develop the cancer.” In the Cervical Cancer Global Review, there is a global call for action in low income and middle income countries.
Planned Parenthood
According to Dr. Cecilia Norris, a primary care physician in Iowa City, “If you’re uninsured, like many of my patients, Planned Parenthood is the only remotely affordable option (for women’s healthcare) in town.”27 About 40 percent of Planned Parenthood’s revenue for services, not including abortions, such as contraception, sexually transmitted infection testing and cancer screening, come from the government, mostly through Medicaid. There has been recent talk by the GOP to defund Planned Parenthood and use money for community healthcare clinics instead. If this becomes the case, these community health care centers would have to scale up their family planning departments.28 According to PBS Newshour, Planned Parenthood says its yearly workload includes 4.5 million tests and treatments for sexually transmitted diseases and 900,000 cancer tests and treatments. Eighty percent of Planned Parenthood’s clients earn 150 percent of the federal poverty level or less.29 Proponents of Planned Parenthood argue that a decrease in funding will only harm those who need the healthcare services it provides the most.
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