The 10 Deadliest Cancers and Why There's No Cure

The dread and fear that can come with a cancer diagnosis have their roots in its killer nature: It's the No. 2 cause of death in Americans, second only to heart disease, according to the Centers for Disease Control and Prevention. Even when diagnosed early and attacked with the latest treatments, it still has the power to kill.

While there are many successful treatments today that didn't exist just a couple decades ago, a wholesale “cure for cancer” remains elusive for many reasons. There are more than 100 types of cancer, characterized by abnormal cell growth. There are many different causes, ranging from radiation to chemicals to viruses; an individual has varying degrees of control over exposure to cancer-causing agents.

Cancer cells, and how they grow, remain unpredictable and in some cases mysterious. Even after seemingly effective treatments, crafty cancer cells are able to hide out in some patients and resurface. About $200 billion has been spent on cancer research since the early 1970s, and the five-year survival rate for all people diagnosed with cancer in the U.S. has risen from about 50 percent in the 1970s to 65 percent today.

"We would not be where we are if basic and clinical science wasn't funded," Dr. Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, told MyHealthNewsDaily. "Basic science teaches us about mechanisms, about how drugs may be effective, and we take that info and put it into a clinic to find out whether or not those new ideas work in cancer treatment."

Here's a look at the 10 cancers that killed the most people in the United States between 2003 and 2007, the most recent data available, according to the National Cancer Institute (NCI).

1. Lung and bronchial cancer: 792,495 lives. Lung and bronchial cancer
 is the top killer cancer in the United States. Smoking and use of tobacco products are the major causes of it, and it strikes most often between the ages of 55 and 65, according to the NCI. There are two major types: non-small cell lung cancer, which is the most common, and small cell lung cancer, which spreads more quickly. More than 157,000 people are expected to die of lung and bronchial cancer in 2010.

2. Colon and rectal cancer: 268,783 lives. Colon cancer grows in the tissues of the colon, whereas rectal cancer grows in the last few inches of the large intestine near the anus, according to the National Cancer Institute. Most cases begin as clumps of small, benign cells called polyps that over time become cancerous. Screening is recommended to find the polyps before they become cancerous, according to the Mayo Clinic. Colorectal cancer is expected to kill more than 51,000 people in 2010.

3. Breast cancer: 206,983 lives. Breast cancer is the second most common cancer in women in the United States, after skin cancer, according to the Mayo Clinic. It can also occur in men – there were nearly 2,000 male cases between 2003 and 2008. The cancer usually forms in the ducts that carry milk to the nipple or the glands that produce the milk in women. Nearly 40,000 people are expected to die from breast cancer in 2010, according to the NCI.

4. Pancreatic cancer: 162,878 lives. Pancreatic cancer begins in the tissues of the pancreas, which aids digestion and metabolism regulation. Detection and early intervention are difficult because it often progressives stealthily and rapidly, according to the Mayo Clinic. Pancreatic cancer is expected to claim nearly 37,000 lives in 2010, according to the NCI.

5. Prostate cancer: 144,926 lives.
This cancer is the second-leading cause of cancer deaths in men, after lung and bronchial cancer, according to the NCI. Prostrate cancer usually starts to grow slowly in the prostate gland, which produces the seminal fluid to transport sperm. Some types remain confined to the gland, and are easier to treat, but others are more aggressive and spread quickly, according to the Mayo Clinic. Prostate cancer is expected to kill about 32,000 men in 2010, according to the NCI.

6. Leukemia: 108,740 lives.
There are many types of leukemia, but all affect the blood-forming tissues of the body, such as the bone marrow and the lymphatic system, and result in an overproduction of abnormal white blood cells, according to the NCI. Leukemia types are classified by how fast they progress and which cells they affect; a type called acute myelogenous leukemia killed the most people – 41,714 – between 2003 and 2007. Nearly 22,000 people are expected to die from leukemia in 2010.

7. Non-Hodgkin lymphoma: 104,407 lives.
This cancer affects the lymphocytes, a type of white blood cell, and is characterized by larger lymph nodes, fever and weight loss. There are several types of non-Hodgkin lymphoma, and they are categorized by whether the cancer is fast- or slow-growing and which type of lymphocytes are affected, according to the NCI. Non-Hodgkin lymphoma is deadlier than Hodgkin lymphoma, and is expected to kill more than 20,000 people in 2010.

8. Liver and intrahepatic bile duct cancer: 79,773 lives.
Liver cancer is one of the most common forms of cancer around the world, but is uncommon in the United States, according to the Mayo Clinic. However, its rates in America are rising. Most liver cancer that occurs in the U.S. begins elsewhere and then spreads to the liver. A closely related cancer is intrahepatic bile duct cancer, which occurs in the duct that carries bile from the liver to the small intestine. Nearly 19,000 Americans are expected to die from liver and intrahepatic bile duct cancer in 2010, according to the NCI.

9. Ovarian cancer: 73,638 lives.
Ovarian cancer was the No. 4 cause of cancer death in women between 2003 and 2007, according to the NCI. The median age of women diagnosed with it is 63. The cancer is easier to treat but harder to detect in its early stages, but recent research has brought light to early symptoms that may aid in diagnosis, according to the Mayo Clinic. Those symptoms include abdominal discomfort, urgency to urinate and pelvic pain. Nearly 14,000 women are expected to die of ovarian cancer in 2010, according to the NCI.

10. Esophageal cancer: 66,659 lives
This cancer starts in the cells that line the esophagus (the tube that carries food from the throat to the stomach) and usually occurs in the lower part of the esophagus, according to the Mayo Clinic. More men than women died from esophageal cancer between 2003 and 2007, according to the NCI. It is expected to kill 14,500 people in 2010.

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