Cancer is a disease that begins as a renegade human cell over which the body has lost control. In order for the body and its organs to function properly, cell growth needs to be strictly regulated. Cancer cells, however, continue to divide and multiply at their own speed, forming abnormal lumps, or tumors. An estimated 6.7 million people currently die from cancer every year.
Not all cancers are natural-born killers. Some tumors are referred to as benign because they don't spread elsewhere in the body. But cells of malignant tumors do invade other tissues and will continue to spread if left untreated, often leading to secondary cancers.
Cancers can start in almost any body cell, due to damage or defects in genes involved in cell division. Mutations build up over time, which is why people tend to develop cancer later in life. What actually triggers these cell changes remains unclear, but diet, lifestyle, viral infections, exposure to radiation or harmful chemicals, and inherited genes are among factors thought to affect a person's risk of cancer.
Lung cancer is the world's most killing cancer. It claims about 1.2 million victims a year. Most of those victims are smokers, who inhale cancer-causing substances called carcinogens with every puff. Experts say around 90 percent of lung cancer cases are due to tobacco smoking.
Breast cancer now accounts for almost one in four cancers diagnosed in women. Studies suggest the genes you inherit can affect the chances of developing the illness. A woman with an affected mother or sister is about twice as likely to develop breast cancer as a woman with no family history of the disease. Lifestyle may also have an influence, particularly in Western countries where many women are having children later. Women who first give birth after the age of 30 are thought to have a three times greater risk of breast cancer than those who became mothers in their teens.
Geographical Distinctions
There are also stark geographic differences, with incidence rates varying by as much as thirtyfold between regions. In much of Asia and South and Central America, for example, cervix cancer is the most deadly in females. However, in North America and Europe another kind of gynecological cancer, ovarian cancer, is a more serious threat.
Among males, southern and eastern Africa record the second and third highest rates of oesophageal, or gullet, cancer after China, but western and central regions of Africa have the lowest incidence in the world. Differences in diet may explain this.
Nevertheless, the reasons why many cancers develop remain elusive. Brain cancer, leukemia (blood cancer), and lymphoma (cancer of the lymph glands) are among types that still mystify scientists.
Treatments
Yet ever more people are surviving diagnosis thanks to earlier detection, better screening, and improved treatments. The three main treatment options are surgery, radiotherapy and chemotherapy. Radiotherapy, also called radiation therapy, involves blasting tumors with high-energy x-rays to shrink them and destroy cancerous cells. Chemotherapy employs cancer-killing drugs.
Even so, future cancer cases are predicted to climb, since the world's population is aging. The proportion of people over age 60 is expected to more than double by 2050, rising from 10 percent to 22 percent. This will add an estimated 4.7 million to the cancer death toll by 2030.
You May Also Like
Go Further
Animals
- Octopuses have a lot of secrets. Can you guess 8 of them?
- Animals
- Feature
Octopuses have a lot of secrets. Can you guess 8 of them? - This biologist and her rescue dog help protect bears in the AndesThis biologist and her rescue dog help protect bears in the Andes
- An octopus invited this writer into her tank—and her secret worldAn octopus invited this writer into her tank—and her secret world
- Peace-loving bonobos are more aggressive than we thoughtPeace-loving bonobos are more aggressive than we thought
Environment
- Listen to 30 years of climate change transformed into haunting musicListen to 30 years of climate change transformed into haunting music
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- U.S. plans to clean its drinking water. What does that mean?U.S. plans to clean its drinking water. What does that mean?
- Food systems: supporting the triangle of food security, Video Story
- Paid Content
Food systems: supporting the triangle of food security - Will we ever solve the mystery of the Mima mounds?Will we ever solve the mystery of the Mima mounds?
History & Culture
- Strange clues in a Maya temple reveal a fiery political dramaStrange clues in a Maya temple reveal a fiery political drama
- How technology is revealing secrets in these ancient scrollsHow technology is revealing secrets in these ancient scrolls
- Pilgrimages aren’t just spiritual anymore. They’re a workout.Pilgrimages aren’t just spiritual anymore. They’re a workout.
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- This ancient cure was just revived in a lab. Does it work?This ancient cure was just revived in a lab. Does it work?
Science
- The unexpected health benefits of Ozempic and MounjaroThe unexpected health benefits of Ozempic and Mounjaro
- Do you have an inner monologue? Here’s what it reveals about you.Do you have an inner monologue? Here’s what it reveals about you.
- Jupiter’s volcanic moon Io has been erupting for billions of yearsJupiter’s volcanic moon Io has been erupting for billions of years
- This 80-foot-long sea monster was the killer whale of its timeThis 80-foot-long sea monster was the killer whale of its time
Travel
- How to plan an epic summer trip to a national parkHow to plan an epic summer trip to a national park
- This town is the Alps' first European Capital of CultureThis town is the Alps' first European Capital of Culture
- This royal city lies in the shadow of Kuala LumpurThis royal city lies in the shadow of Kuala Lumpur
- This author tells the story of crypto-trading Mongolian nomadsThis author tells the story of crypto-trading Mongolian nomads