Knowledge and understanding of cancer, the leading cause of death in the United States and worldwide, has grown exponentially in the last 20 years. Investment in research and technology has greatly reduced the effects of cancer through advances in prevention, detection, and treatment. Survival rates have never been greater: in 2003, the rate of cancer deaths dropped in the United States for the first time since 1930.
I. Causes of Cancer
II. Remedies and Care
C. Gene Expression Profiling
III. Improving Outcomes
Causes of Cancer
Radically different approaches to prevention and treatment, despite their successes, continue to divide the medical and scientific communities. Developments in cancer research stretch across the medical spectrum. From identifying new drugs to developing new screening tests and implementing more effective therapies, breakthroughs occur every day. Each of the 100 different types of cancers affects the body in unique ways and requires specific prevention, detection, and therapy plans. Understanding the complexities of this disease, which afflicts more than half of all men and a third of all women in the United States, is vital to the medical health of the nation.
The causes of cancer are becoming better understood. Genetics and lifestyle both can contribute to a person’s susceptibility to cancer. For example, diet can greatly affect a person’s chances of getting cancer. Certain lifestyle choices—such as having excess body fat, eating red meat, not engaging in physical exercise, or consuming alcohol—all seem to increase the likelihood of developing cancer. Many cancers tend to be caused by long-term exposure to cancer-causing agents, such as environmental toxins, rather than by a single incident. Environmental factors and lifestyle choices, however, do not always predict the appearance of cancer; instead, they should be taken as indicators of a higher risk. Understanding how these things interact with genetic factors over the course of a person’s life is the front line for future cancer research.
Remedies and Care
The treatment of cancer used to entail surgery, chemotherapy, radiation, or a combination of the three. Although these types of procedures have altered the medical landscape for treating cancer over the past 100 years, new methods have emerged that bypass invasive or problematic surgeries. Researchers have begun to understand how the body fights cancer on its own through the immune system. Many of the developments in fighting cancer have come through the harnessing of the immune system’s ability to produce antigens to combat cancerous cells.
Therapy in the form of cancer vaccines has been largely experimental. Recently, however, the U.S. Food and Drug Administration (FDA) approved a major breakthrough in cancer prevention using vaccines.
The development of a vaccine against the human papillomavirus (HPV) marked the first vaccine to gain approval in the fight against cancer since the hepatitis B vaccine. HPV is a leading cause of cervical cancer and, to a lesser degree, other types of cancer. The vaccine, which has gained FDA approval, was shown to be 100 percent effective against two of the leading types of HPV virus. These two strains account for 70 percent of all cervical cancers worldwide.
Vaccines for cancer can either prevent the disease directly (therapeutic vaccines) or prevent its development (prophylactic vaccines). Therapeutic vaccines are used to strengthen the body against existing cancers so as to prevent the reappearance of cancerous cells. Prophylactic vaccines, like the one for HPV, prevent the invasion of viruses that ultimately cause cancer. The HPV vaccine represents a significant breakthrough in cancer research. There are no officially licensed therapeutic vaccines to date, although numerous prophylactic vaccines are being tested by the National Cancer Institute.
Vaccines are part of a growing area of treatment known as biological therapy or immunotherapy. Biological therapy uses the body’s immune system to fight cancer or lessen certain side effects of other cancer treatments. The immune system acts as the body’s defense system, though it does not always recognize cancerous cells in the body and often lets them go undetected. Furthermore, the immune system itself may not function properly, allowing cancerous cells to recur in a process called metastasis, wherein the cancerous cells spread to other parts of the body. Biological therapy seeks to step in to enhance or stimulate the body’s immune system processes.
One of the new dimensions of cancer research has been the revolution of personalized, or molecular, medicine. Personalized medicine takes into account knowledge of a patient’s genotype for the purpose of identifying the right preventive or treatment option. With the success of the Human Genome Project, new approaches have emerged in the field of cancer research. Approaching cancer from the perspective of “disease management” will lead to more customized medical treatments.
The successful implementation of such a revolutionary way of handling the disease will require that a vast amount of genetic data be classified, analyzed, and made accessible to doctors and researchers to determine treatments for individual patients. In 2004, cancer centers across the United States took part in the implementation of the National Cancer Institute’s cancer Biomedical Informatics Grid (caBIG), a virtual community that seeks to accelerate new approaches to cancer research. The caBIG community aims to establish an open-access database that provides researchers the necessary infrastructure for the exchange of genetic data.
Gene Expression Profiling
New methods for detecting cancer have also been making headlines. One such method has been gene expression profi ling, a process that is capable of identifying specific strains of cancer using DNA microarrays. These microarrays identify the activity of thousands of genes at once, providing a molecular profile of each strain. Research has demonstrated two important guidelines in cancer identification and treatment. Even though certain types of cancer look similar on a microscopic level, they can differ greatly on a molecular level and may require vastly different types of therapy.
The most notable example of this type of process has been used to identify two different strains of non-Hodgkin’s lymphoma (NHL), a cancer of the white blood cells. Two common but very different strains of NHL call for radically differing treatments, such that the ability to easily diagnose which strain is active has been a great boon for treatment. In the past, failure to diagnose the different strains has led to therapeutic errors and resulted in lower survival rates.
Another innovation in cancer detection involves the field of proteomics. Proteomics— the study of all the proteins in an organism over its lifetime—entered into the discussion about cancer detection when it was discovered that tumors leak proteins into certain bodily fluids, such as blood or urine. Because tumors leak specific types of proteins, it is possible to identify the proteins as “cancer biomarkers.” If such proteins can be linked to cancers, then examining bodily fluids could greatly increase the ability to screen patients for cancer at the earliest stages.
Certain proteins have already been implemented as cancer biomarkers. Levels of certain antigens—types of protein found in the immune system—can indicate cancer of the prostate (in men) or of the ovaries (in women). This method of detection has not yet proved to be 100 percent effective. It may give false negatives in which the test may not detect cancer when it is actually present or even false positives where it may detect cancer in cancer-free patients.
As processes for detecting cancer improve, the number of cancer diagnoses is likely to increase. Although this would increase the overall incidence of cancer, it would also decrease its lethal consequences.
Traditional forms of cancer treatment—surgery, chemotherapy, and radiation—are also undergoing significant breakthroughs. Developments in traditional cancer treatment involve refining existing procedures to yield better outcomes and reducing the side effects typically associated with such treatments. For example, chemotherapy regimens for head and neck cancers, typically difficult to treat, have improved through recombination of chemotherapy treatments with radiation, the first such major improvement for that type of cancer in 45 years.
Chemotherapy solutions are also being affected by the genetic revolution. A burgeoning field called pharmacogenomics seeks to tailor pharmaceutical offerings to a patient’s genetic makeup, abandoning the one-size-fits-all or “blockbuster” drug of previous years. Drugs will now be matched using knowledge of a patient’s gene profile, avoiding the trial-and-error method that is often practiced in trying to find the correct treatment for a given patient. Patients will be able to avoid unwanted side effects from unnecessary drugs, as well as lower the cost of health care and reduce repeat medical visits.
Much ground must still be covered before a pharmacogenomics revolution can take place. Drug alternatives must be found for numerous genotypes to avoid leaving patients without any options if their genotypes do not match the drugs available. Drug companies must also have incentives to make specialized drugs, given the exorbitant cost of offering only one single drug.
The effects of cancer and cancer treatments will continue to be studied as more information on the long-term effects of certain diseases becomes available. New examples of long-term complications with cancer have emerged recently in survivors of both breast cancer and childhood cancer. Breast cancer survivors have reported fatigue 5 and even 10 years after their treatment. Similarly, long-term research into childhood cancer survivors has shown that children who survive cancer are much more likely to have other health problems, five times more frequently than their healthy siblings. A large percentage of childhood survivors often developed other cancers, heart disease, and scarring of the lungs by age 45. Such evidence underscores the complicated nature of cancer survival and the fact that long-term studies will continue to play an important role.
There are now more than 10 million cancer survivors in the United States alone. The cancer survival rate between 1995 and 2001 was 65 percent, compared with just 50 percent from 1974 to 1976. As more becomes known about cancer itself, more will also be learned about the effects of cancer after remission. Studies examining cancer survivors 5 to 10 years after surgery are revealing that the effects of cancer and cancer treatment can extend beyond the time of treatment.
Not all research into cancer has been positive: certain types of cancer—namely skin cancer, myeloma (cancer of plasma cells in the immune system), and cancers of the thyroid and kidney—are on the rise. The reasons for the increase in cancers are wideranging and require further research to be fully understood.
With the fight against cancer continuing to evolve, new advances continue to converge from different fronts—in the use of human biospecimens, nanotechnology, and proteomics. Each of these fields individually has contributed to the efforts at detecting, preventing, and treating cancer, but if these efforts can be streamlined and pooled, a major battle in the fight against cancer will have been won.
As the fight has taken on a more global character, developments in knowledge sharing and community support have provided cancer researchers, patients, and survivors with new means of battling this life-threatening disease. As the technologies and infrastructures change, however, public policy will also have to change the way advancements in medical science are linked with accessibility for patients, so that financial means will not be a prerequisite for receiving these new treatments.
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