Cancer and Risk Factors

Defining Cancer

Malignancies – a tumor made of cancer cells that can invade nearby tissues.

Cancer is a general term that covers a plethora of different malignancies. These pathogenic conditions are characterized by uncontrolled cellular proliferation and growth, and under special conditions, tumor cell migration, invasion, and spreading to other organs and tissues.

Different factors and conditions can transform normal cells into cancerous ones by altering their normal function. The complexity of these biochemical processes and networks represents a significant challenge in identifying the changes to initiate and maintain cancer progression.

Although our understanding of human cancer’s biology is not fully complete, numerous genes and proteins that are causally involved in cancer initiation and progression have been identified in the past few years.

Cancer Worldwide

According to the International Agency for Research on Cancer:

Cancer is one of the leading causes of death worldwide. In 2018, there were 18.1 million new cases and 9.5 million cancer-related deaths worldwide.

By 2040, the number of new cancer cases per year is expected to rise to 29.5 million and cancer-related deaths to 16.4 million.

Cancer classification and types

There are more than one hundred and twenty types of cancer classified into two types:

  1. Histological– The type of tissue that cancer comes from 
  2. Primary site– Where the cancer first developed in the body 

Histologically the many different cancers are grouped into six major categories:

  1. Carcinoma – Cancer of the internal or external lining of the body. Accounts for 80 to 90 % percent of all cancer cases.
  2. Sarcoma – Cancer that originates in supportive and connective tissues such as bones, tendons, cartilage, muscle, and fat. It is generally occurring in young adults.
  3. Myeloma – Cancer that originates in the plasma cells of bone marrow.
  4. Leukemia – Cancers of the bone marrow – the site of blood cell production.
  5. Lymphoma – Cancer in the glands or nodes of the lymphatic system.
  6. Mixed Types – Cancer type components may be in one category or from different categories.

Here are the types of cancer diagnosed with the most significant frequency in the United States, excluding nonmelanoma skin cancers:

Cancer Type Estimated New Cases Estimated Deaths
Bladder 81,400 17,980
Breast (Female – Male) 276,480 – 2,620 42,170 – 520
Colon and Rectal (Combined) 147,950 53,200
Endometrial 65,620 12,590
Kidney (Renal Cell and Renal Pelvis)  73,750 14,830
Leukemia (All Types) 60,530 23,100
Liver and Intrahepatic Bile Duct 42,810 30,160
Lung (Including Bronchus) 228,820 135,720
Melanoma 100,350 6,850
Non-Hodgkin Lymphoma 77,240 19,940
Pancreatic 57,600 47,050
Prostate 191,930 33,330
Thyroid 52,890 2,180
Source – National Cancer Institute

Why do people get cancer?

It’s difficult to know why one person develops cancer, and another doesn’t. There are risk factors that increase a person’s chances of developing cancer and protective factors that lower cancer risk. 

There are environmental and genetic factors, as well as certain behavioral factors. Also, the types of cancers that are most common vary considerably from country to country or region to region.

Scientists study large groups of people who have developed cancer and compare them to people who have not. They look at environmental factors the group is exposed to and the behavioral aspects. From this, certain substances and behaviors have been identified as things that may cause cancer.

The following list is some of the known or suspected cancer risk factors.

Age – For many of the cancer types advancing age is the most critical risk factor overall. For example, the median age for breast cancer diagnosis is 61 years, for colorectal cancer 68 years, lung cancer 70 years, and 66 years for prostate cancer.

However, cancers such as bone cancer, leukemia, and neuroblastoma are more frequently diagnosed in children and adolescents under 20 years of age.

Alcohol – The more alcohol you drink increases the risk of cancer of the breast, esophagus, larynx, liver, mouth, and throat. Add tobacco and the risk goes significantly higher. If you drink, do so moderately. Two drinks per day for men and one drink per day for women is considered moderate.

Cancer-Causing Substances – Exposure to certain substances can damage your DNA, negatively impacting cell division, and contribute to cancer development. Some may be avoided, such as tobacco smoke and UV rays, but many are in our environment in the air, water, food, and specific materials.

The list of carcinogens the most likely to affect human health is extensive. Some of the most well-known carcinogens are asbestos, Nickel, Cadmium, Radon, vinyl chloride, and benzene.

Chronic Inflammation – Inflammation is a normal response to injury and a part of the healing process. However, an inflammatory process may begin without injury, and it does not end when it should. It is not always known why inflammation continues. This chronic inflammation can damage DNA and lead to cancer.

Diet – Certain dietary elements and nutrients are associated with increases as well as decreases in cancer risk. Body composition, in particular, obesity and levels of physical activity can impact the cancer process. There is no specific diet that will cure cancer, but a healthy diet may decrease your cancer risk.

Infectious Agents – Infectious agents, such as viruses, bacteria, and parasites, can increase cancer risk or cause cancer. Certain viruses may disrupt signals that typically keep cell growth and proliferation in check. 

Infections can weaken the immune system, so the body cannot fight off other cancer-causing infections. Some viruses, bacteria, and parasites can cause chronic inflammation, leading to cancer.

Sunlight – UV radiation from the sun is linked to skin cancer’s three most common types, basal cell carcinoma, squamous cell carcinoma, and malignant melanoma. Together these cancers affect more than a million Americans annually. Ultraviolet light also benefits your health by the natural synthesis of vitamin D, which is good for the immune system. However, excessive exposure to UV carries profound health risks.

Tobacco – The leading cause of cancer and death from cancer is smoking tobacco. People who use tobacco products or regularly around secondhand smoke have an increased risk of cancer because tobacco has many chemicals that damage DNA. 

The cancer types include cancer of the lungs, larynx, mouth, esophagus, throat, bladder, kidney, liver, stomach, pancreas, colon and rectum, cervix, and acute myeloid leukemia.

If you are a smoker, don’t you think maybe you should quit?

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