Cancer: Medicine’s Greatest Challenge

Cancer is not one but a collection of diseases that account for more than half a million deaths in the United States and more than 7 million deaths worldwide each year. All cancers have one thing in common—uncontrolled cell growth. Unlike diseases caused by invading bacteria or viruses, cancer occurs when our own cells are transformed into tumors that damage and disrupt the body’s normal functions. This makes cancer one of medicine’s greatest challenges. Understanding cancer means understanding the vast, complex machinery of human cells, from their genetic blueprints to their interactions with other cells and tissues.

What is Breast Cancer?   +

Breast cancer is the most common cancer among women, but there is some good news about the breast cancer epidemic. 

After increasing for more than 20 years, new cases have been declining by about 2% each year since 1998 in women over 50. Researchers believe this is partly due to the declining use of hormone replacement therapy (HRT) after menopause, which followed publication of a study that linked HRT to increased breast cancer risk. Deaths from breast cancer also have declined since 1990, thanks to earlier detection and improving therapies.

For many women, breast cancer can now be managed as a chronic disease. When found early before a tumor has spread, 5-year survival is 99%. Overall, 10-year survival rates for all stages of disease have climbed to 82%. Early detection is vital: survival rates are still poor for women diagnosed with late-stage metastatic cancer that has spread to other parts of the body. 

Women have a higher risk for developing the disease if breast cancer runs in their families and if they have certain inherited gene mutations (BRCA1 and BRCA2). They have a lower risk if they have had children and have breast fed. Obesity increases risk for many cancers, including breast cancer; the rise in obesity could threaten the downward cancer trends seen in recent years. 

Genetics research is giving scientists and physicians deeper understanding of different types of breast cancer. Three general types have been identified. In one type, tumor growth is driven by signals through estrogen receptors on cell surfaces; an estimated 60% of women have this type. About 25% of women have the second type, in which tumor growth is driven by another type of receptor, called “HER2.” In the third type, neither estrogen nor HER2 receptors play a role.

The ability to identify cancer subtypes is advancing therapy, allowing physicians to tailor treatment for the individual patient and improve its effectiveness. For example, women who are HER2 positive can be treated with Herceptin, a hormonal therapy that targets HER2.

Treatment usually combines surgery to remove tumors and affected lymph nodes, followed by some combination of radiation, chemotherapy and hormonal therapy. The treatment approach depends on the stage (tumor size) and spread of the disease. Genetic features and biological markers (biomarkers) of an individual’s tumor are also used to guide treatment plans. 


American Cancer Society, Cancer Facts and Figures 2012

What is Lung Cancer?   +

Lung cancer is the leading cause of cancer-related deaths in the United States, where an estimated 226,000 new cases are expected to be diagnosed in 2011. Although survival rates have been increasing for patients with advanced disease, lung cancer still claims more lives than colon, breast and prostate cancers combined. 

Physicians distinguish types of lung cancer by cell type. There are two broad categories—small cell (SCL), and non-small cell (NSCL), which represent about 80% of all lung cancers. The most common symptom is a persistent cough. This makes it difficult to diagnose lung cancer early when there are the most options for effective treatment. 

Most patients are diagnosed when lung cancer has progressed to stage III or stage IV. In stage III, the cancer is local, meaning that it still confined to the lungs. About 30% to 40% of new cases are diagnosed at stage III. In stage IV metastatic disease, the cancer has spread to other parts of the body. About 40% of cases are diagnosed at stage IV.

Tobacco use is the most important risk factor for lung cancer, accounting for about 80% of lung cancer cases in men and 50% in women. Other risk factors include secondhand smoke and workplace exposure to radon, asbestos and some chemicals, and exposure to air pollution and coal smoke. Lung cancer is rare in people under age 45.

Preventing tobacco use is the single most important weapon in the worldwide fight against this disease. People who quit smoking before 50 cut their risk of death in the next 15 years by half, compared to those who continue to smoke.
What is Prostate Cancer?   +

Prostate cancer is the second most common cause of cancer death in man of all ages, and the most common cause in men over age 75. More than 241,800 new cases are expected in the United States in 2012.

This cancer starts in the prostate gland, a walnut-sized gland that is part of the male reproductive system. The prostate wraps around the urethra, the tube that carries urine out of the body. Common symptoms include delayed or slow urinary stream and blood in the urine or semen. Almost all men experience an enlarged prostate as they age, but this does not increase risk for prostate cancer. The biggest risk factors are age, race (African-American men have higher risk) and family history. Obesity and smoking increase the risk of dying from prostate cancer.

For many men—perhaps even most—localized prostate cancer will not progress and will not cause harm. But for some men, what appears to be localized cancer will spread to other parts of the body and eventually be fatal. The difficulty is to determine when treatment is necessary. 
The only definitive test for prostate cancer is a biopsy. Routine prostate screening using the PSA (prostate-specific antigen) blood test has benefits and limitations. The chances of having prostate cancer increase as the PSA level goes up. But PSA levels can also be increased by a number of other things, including enlarged prostate, age, and infection. Other factors can cause PSA levels to go down even when cancer is present, including certain medicines and herbal supplements.

The U.S. Preventive Services Task Force has questioned the value of PSA testing because it often leads to needless treatments. The American Cancer Society’s screening guidelines are available to view here.

Despite the limitations of testing, the number of deaths from prostate cancer has decreased since screening has come into wide use. The earlier cancer is detected, the more treatable the disease is.
What is Lymphoma?   +

Lymphoma is a cancer that affects blood cells in the immune system—usually white blood cells called B-cells and T-cells that fight infections. These cells are part of the lymphatic system, which includes the lymph nodes, spleen and bone marrow. 

There are two general types of lymphoma: Hodgkin and non-Hodgkin lymphoma. Non-Hodgkin lymphoma, or NHL, is the most common. NHL includes a number of subtypes, depending on which cells are affected. Most cases involve B-cells. Other types of NHL involve T-cells or NK-cells. In Hodgkin lymphoma a different type of cell is present—large cancerous cells called Reed-Sternberg cells.

The cause of lymphoma is still unknown. Symptoms of lymphoma can include swollen, painful lymph nodes in the neck, armpits or groin; unexplained weight loss; coughing or chest pain; and weakness and fever.

Risk for Hodgkin lymphoma is highest during adolescence and early adulthood. NHL occurs more often in people over 60, and risk is higher for men. Exposure to radiation and to certain drugs—including anticancer drugs used to treat other cancers—increase the risk for NHL. Disease conditions that affect the immune system, like HIV and Epstein-Barr virus in AIDS patients, increase risk. Immune-suppressing drugs that are used in organ transplantation can also increase risk. 

Treatment has been improving and survival rates have been increasing for the past 20 years. Hodgkin lymphoma is one of the most curable forms of cancer. Today, long-term remission can be achieved for many people with NHL. For more information, contact the Leukemia and Lymphoma Society.
What is Leukemia?   +

Leukemia is a cancer that affects white blood cells. It arises in the bone marrow, the soft spongy tissue inside the bones that makes new blood cells, and it causes white blood cells to grow uncontrollably. There are two main types of leukemia. Lymphocytic leukemia affects blood cells called lymphocytes; myeloid leukemia affects blood cells called granulocytes.

The disease can progress rapidly (acute leukemia) or slowly (chronic leukemia), and it can affect both adults and children. Acute lymphocytic leukemia (ALL) is the most common type in children. Chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) are the most common types in adults. Chronic myeloid leukemia (CML) is less common, accounting for about 12% of all cases.

Leukemia is difficult to diagnose. Symptoms include easy bruising and bleeding, paleness and fatigue, and slow healing of minor scrapes and cuts. People suffering from chronic leukemia may have no signs or symptoms. Blood tests are necessary to diagnose leukemia.

The causes of the disease are not fully understood, but genetics studies are revealing important information about how changes in DNA cause changes in bone marrow cells. For example, the BCR-ABL gene is known to play a role in the development of CML. Risks for leukemia include long-term exposure to the chemical benzene, excessive radiation, and certain drugs used to treat other types of cancer. 

Great progress has been made in treating leukemia, especially childhood leukemia where survival rates have increased to more than 80% thanks to advancing knowledge and innovative therapies. While the number of new cases remains steady, survival rates for leukemia patients have been rising for several decades. The Leukemia and Lymphoma Society offers patient information and support. 

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