Eventually, the pace of the cell cycle speeds up as the effectiveness of the control and repair mechanisms decreases. Uncontrolled growth of the mutated cells outpaces the growth of normal cells in the area, and a tumor can result.

Tumor suppressors. Negative regulators of the cell cycle may be less active (or even nonfunctional) in cancer cells. For instance, a protein that halts cell cycle progression in response to DNA damage may no longer sense damage or trigger a response.

Disruption of the normal regulation of cell-cycle progression and division are important events in the development of cancer. Complex networks of regulatory factors respond to the tumor microenvironment and stress signals, such as those resulting from damaged DNA, dictate whether cells proliferate or die.

Cancer: mitosis out of control If that happens in just a single cell, it can replicate itself to make new cells that are also out of control. These are cancer cells. They continue to replicate rapidly without the control systems that normal cells have.

What Causes Cancer?

• Smoking and Tobacco.
• Diet and Physical Activity.
• Sun and Other Types of Radiation.
• Viruses and Other Infections.

Red meat includes pork, beef, veal, and lamb. Processed meat includes bacon, ham, lunch meats, meat jerky, hot dogs, salami, and other cured meat products. Any amount of processed meat and more than around 18 ounces of fresh meat per week are most strongly linked with a higher risk of cancer.

Signs of Cancer

• Change in bowel or bladder habits.
• A sore that does not heal.
• Unusual bleeding or discharge.
• Thickening or lump in the breast or elsewhere.
• Indigestion or difficulty in swallowing.
• Obvious change in a wart or mole.
• Nagging cough or hoarseness.

There are no cures for any kinds of cancer, but there are treatments that may cure you. Many people are treated for cancer, live out the rest of their life, and die of other causes. Many others are treated for cancer and still die from it, although treatment may give them more time: even years or decades.

During the 3 decades, the proportion of survivors treated with chemotherapy alone increased (from 18% in 1970-1979 to 54% in 1990-1999), and the life expectancy gap in this chemotherapy-alone group decreased from 11.0 years (95% UI, 9.0-13.1 years) to 6.0 years (95% UI, 4.5-7.6 years).

The radiation beams change the DNA makeup of the tumor, causing it to shrink or die. This type of cancer treatment has fewer side effects than chemotherapy since it only targets one area of the body.

In the standard treatment sequence, radiation therapy doesn’t start until the chemotherapy regimen is done. The traditional external beam radiation therapy treatment schedule usually requires daily trips to the hospital or cancer center — usually 5 days a week for 4 to 6 weeks.

Specific side effects of radiation therapy that affect parts of the body

• Headaches.
• Hair loss.
• Nausea.
• Vomiting.
• Extreme tiredness (fatigue)
• Hearing loss.
• Skin and scalp changes.
• Trouble with memory and speech.

Most patients get radiation treatments daily, 5 days a week (Monday through Friday) for 5 to 8 weeks. Weekend rest breaks allow time for normal cells to recover.