Page 3 Complete Your CE Test Online - Click Here After these, men’s and women’s cancer incidence and mortality diverge significantly. In men, bladder cancer is the fourth most common cancer diagnosed and melanoma is the fifth most common cancer diagnosed. But liver cancer and leukemia are the fifth and sixth leading causes of cancer death in men. In women, cancer of the uterus (endometrium) and thyroid are the fourth and fifth most common cancers. But in cancer-related mortality in women, ovarian cancer ranks fifth and uterine cancer ranks sixth. Because men do not develop uterine or ovarian cancers because of anatomy, and because these cancers are not as common as breast cancer, these two sex-specific cancers are not represented in rankings for the combined U.S. adult population. Costs of cancer Cancer treatment involves a lot of medical care, and the financial aspects of this cannot be dismissed. There is a growing awareness among health care professionals that the cost of cancer care is rising quickly. The term financial toxicity has made its way into the medical lexicon indicating that there are patients who cannot afford recommended treatments or prescriptions. This directly affects patient care and outcomes. The Agency for Health Care Research and Quality (AHRQ) reported that each year from 2012 to 2013, more than 1 million people had inpatient hospital stays related to cancer; 14.5 million people had hospital outpatient visits or office visits related to cancer; and more than 5 million people had prescription medicines related to cancer. Medical expenses have increased, with outpatient costs increasing much faster relative to inpatient costs as cancer care increasingly moves to outpatient models. The AHRQ Medical Expenditure Panel Survey (MEPS) found the following: ● ● Medical spending to treat cancer increased from $56.8 billion in 2001 (adjusted for inflation to 2011) to $88.3 billion in 2011. ● ● Inpatient expenses were 47% of total spending for cancer treatment in 2001, but went down to 35% by 2011. ● ● The cost for ambulatory and outpatient care and treatment of cancer went up from $25.5 billion in 2001 to $43.8 billion in 2011. ● ● Prescription medications from retail pharmacies for cancer climbed from $2 billion in 2001 to $10 billion in 2011. WHAT IS CANCER? Although individuals often speak of cancer as though it were a singular illness, the National Cancer Institute describes cancer as a collection of more than 100 related diseases. Other organizations that keep track have calculated different numbers of cancers. A cancer can begin almost anywhere in the human body, as each body contains trillions of cells. All cancers share the characteristics of abnormal cells growing at uncontrolled/abnormal rates that continue to divide and traffic or grow into surrounding tissues. Normal cell development Normally, human cells grow and divide to form new cells as needed by the body. Normal cells are able to perform their specific functions: they respond to signals and cytokines, and cell division is inhibited by contact and other mechanisms. When cells grow old or become damaged, they die, a process known as apoptosis, or programmed cell death. Waste products are removed and new cells are generated to take the place of the dead cells. Abnormal cell development When a cancer develops, the orderly process of normal cell division, death, and replacement breaks down. As cells become more and more abnormal, old or damaged cells survive when they should die, and new cells form when they are not needed. These extra cells divide without stopping and may form solid masses or abnormal cells that may be found in the circulatory system. These abnormal cells take over nutrients and blood supply in the area of the cancer at the expense of the normal cells. Not all cancer cells grow at the same speed, but they tend to reproduce more rapidly than normal cells. Many cancers form solid tumors or tissue masses. Cancers of the blood – for example, leukemias – generally do not form solid tumors, as abnormal cells reproduce in the hematopoietic (blood-forming) or lymphatic organs of the body. Cancerous tumors can spread into or invade nearby tissues, growing and expanding past normal tissue borders. Another way that cancerous tumors spread is through some cancer cells breaking off and traveling to other locations in the body via blood circulation or the lymphatic system. Some of these migrating abnormal cells form metastases far from the original tumor. Genetic changes in cancer Cancers have a genetic component, meaning that the abnormal cell cycles are caused by mutations to genes that control the way cells function, especially those that direct growth and division. It often takes many mutations before a cell becomes cancerous. Genes are constantly mutating as cells divide and, typically, the errors are detected and the body is able to repair them. Other errors cause malfunction or death of the cell. Some genetic mutations do not cause observable effect on the cell function, but others mutations can start or continue in a chain of events that lead to cancer. Germline versus acquired genetic mutations Genetic changes that can start a cell on a cancerous path or that allow abnormal cells to grow and divide can be inherited from parents. Germline mutations, because humans begin from a single sperm and a single egg combining deoxyribonucleic acid (DNA), are present in all body cells. Inherited germline mutations can be passed on to offspring, depending on recombination and reproduction events. Even seemingly insignificant mutations can produce diseases; for example, an inherited defect in one gene can cause Huntington’s disease. Often, the initial genetic mutations that lead to cancer arise during a person’s lifetime. These acquired mutations, called sporadic or somatic mutations, are present only in the abnormal cells. They can result from errors that occur as cells divide. Every time a cell divides, there is a chance of this kind of error or because of damage to DNA caused by certain environmental exposures. Cancer-causing environmental exposures include such substances as the chemicals in tobacco smoke, and radiation from X-rays and ultraviolet rays (UV) from the sun (see “Cancer Risk Factors”). Acquired mutations can accumulate over a lifetime, which is part of the reason why older people have a higher risk of cancer. Even an individual with a germline mutation that predisposes that person to cancer needs additional genetic mutations before cancer results. The germline mutation provides the foundation of abnormal genetics for acquired mutations to build on. This can speed up the process of cancer development and is one of the reasons that inherited cancer syndromes often produce cancer earlier in life. Proto-Oncogenes, Tumor Suppressor Genes, and DNA Repair Genetic changes that contribute to cancer tend to affect three main types of genes. These changes are sometimes called “drivers” of cancer. 1. Proto-oncogenes. 2. Tumor suppressor genes. 3. DNA repair genes. Proto-oncogenes are involved in normal cell growth and division. But when these genes are mutated in certain ways or become more active than normal, they may “go rogue” and become permanently activated. If that activation, occurs they are considered oncogenes (cancer-causing genes), which allow cells to divide and survive when they should not. Tumor suppressor genes are involved in controlling cell growth and division. When tumor suppressor genes are mutated and if this inactivates them, it can cause cancer or allow a cancer to grow. A prominent example is the TP53 gene, which produces the P53 protein. The P53 protein, among other functions, prevents damaged cells from reproducing. This is an important role because damaged cells are more likely to contain mutations that lead to cancer. The inactivation of this tumor suppressor gene plays a role in more than half of all cancers. DNA repair genes are involved in fixing damaged DNA. Cells with mutations in the DNA repair genes tend to develop additional mutations in other genes. Together, these mutations may help the cells to become cancerous. As scientists have learned more about the molecular changes that lead to cancer, they have found that certain mutations occur in many types of cancer. For example, for a solid tumor to grow more than 2 mm, about the size of a pinhead, it must develop a blood supply. However, there are multiple pathways to develop a blood supply. Cancers are now sometimes characterized by the types of genetic alterations believed to