What causes cancer cells to activate in a normal body?

Ever wondered why so many people around us are getting detected with cancer these days? Growing up, we had heard about worrying diseases like malaria, jaundice, heart attacks but cancer was believed to be a disease that happened to a few. So have the cancer cases suddenly gone up or there are better diagnostics available? Well, there is verified data that suggests death from cancer has gone up in the past few years in India. But what cause cancer cells to activate in normal bodies?
In simple words, cancer cells are normal cells of the body which transform into a malignant clone either due to an internal abnormality in the body or an external factor that influences the body over a prolonged period of time. These factors cause irreversible damage or change in the normal DNA of the cell. These cells with the damaged or changed DNA become free of the general control measures that are present over a normal cell in the body. The loss of growth control over these cells lead to uncontrolled multiplication leading to what we see and feel as tumours / cancers.
 

Elaborating the causes behind cancer, Dr. Wesley M Jose, Clinical Associate Professor, Medical Oncology & Hematology, Amrita Hospital, Kochi says, “Cancer is caused by both internal and external factors. The common internal factors include, genetic mutation, hormones, immune related conditions, over activation and miscommunication of growth factors, and hereditary changes. The external factors are lifestyle, smoking, alcohol consumption, chemical exposure, radiation exposure, viral Infections, prior medical treatments with cytotoxic/cancer drugs.” These factors may work singly or in conjunction with each other to initiate a normal cell to become malignant.
Common risk factors

“While doctors have an idea of what may increase your risk of cancer, the majority of cancers occur in people who don't have any known risk factors,” shares Dr Satyam Taneja, Director, Surgical Oncology, Max Hospital Patparganj.

Factors known to increase your risk of cancer include:

Your age
Cancer can take decades to develop. That's why most people diagnosed with cancer are 65 or older. While it's more common in older adults, cancer isn't exclusively an adult disease — cancer can be diagnosed at any age.

Your habits
Certain lifestyle choices are known to increase your risk of cancer. Smoking, drinking more than one drink a day for women and up to two drinks a day for men, excessive exposure to the sun or frequent blistering sunburns, being obese, and having unsafe sex can contribute to cancer.
You can change these habits to lower your risk of cancer — though some habits are easier to change than others.

Your family history
Only a small portion of cancers are due to an inherited condition. If cancer is common in your family, it's possible that mutations are being passed from one generation to the next. You might be a candidate for genetic testing to see whether you have inherited mutations that might increase your risk of certain cancers. Keep in mind that having an inherited genetic mutation doesn't necessarily mean you'll get cancer.

Your health conditions
Some chronic health conditions, such as ulcerative colitis, can markedly increase your risk of developing certain cancers. Talk to your doctor about your risk.

Your environment
The environment around you may contain harmful chemicals that can increase your risk of cancer. Even if you don't smoke, you might inhale secondhand smoke if you go where people are smoking or if you live with someone who smokes. Chemicals in your home or workplace, such as asbestos and benzene, also are associated with an increased risk of cancer.

The gene mutations you're born with and those that you acquire throughout your life work together to cause cancer. Here Dr Taneja has tried to explain in detail---
 

1. What do gene mutations do?
   A gene mutation can instruct a healthy cell to allow rapid growth, fail to stop uncontrolled cell growth, make mistakes when repairing DNA errors leading cells to become cancerous.These mutations are the most common ones found in cancer. But many other gene mutations can contribute to causing cancer.
2. What causes gene mutations?
   Gene mutations can occur for several reasons, for instance: Gene mutations you're born with. You may be born with a genetic mutation that you inherited from your parents. This type of mutation accounts for a small percentage of cancers. Gene mutations that occur after birth. Most gene mutations occur after you're born and aren't inherited. A number of forces can cause gene mutations, such as smoking, radiation, viruses, cancer-causing chemicals (carcinogens), obesity, hormones, chronic inflammation and a lack of exercise. Gene mutations occur frequently during normal cell growth. However, cells contain a mechanism that recognizes when a mistake occurs and repairs the mistake. Occasionally, a mistake is missed. This could cause a cell to become cancerous.
3. How do gene mutations interact with each other?
   The gene mutations you're born with and those that you acquire throughout your life work together to cause cancer. For instance, if you've inherited a genetic mutation that predisposes you to cancer, that doesn't mean you're certain to get cancer. Instead, you may need one or more other gene mutations to cause cancer. Your inherited gene mutation could make you more likely than other people to develop cancer when exposed to a certain cancer-causing substance. It's not clear just how many mutations must accumulate for cancer to form. It's likely that this varies among cancer types.