The Basics of Cancer

Cancer causes cells to divide uncontrollably. This can result in tumors, damage to the immune system, and other impairment that can be fatal.

In the United States, an estimated 15.5 million people with a history of cancer were living as of January 1, 2016, according to a 2018 report from the American Cancer Society.

In this article, we examine types of cancer, how the disease develops, and the many treatments that help improve the quality of life and survival rates.

What is cancer?

Cancer is a broad term. It describes the disease that results when cellular changes cause the uncontrolled growth and division of cells.

Some cancers promote rapid cell proliferation, while others cause cells to divide and develop more slowly. Some cancers, such as leukemia, produce visible tumors, while others, such as breast cancer, do not.

The majority of the cells in the body have distinct functions and lifespans. While cell death may appear to be a negative phenomenon, it is actually a natural and helpful process known as apoptosis.

A cell is told to die so that the body can replace it with a newer, better-functioning cell. The components that tell cancerous cells to cease proliferating and die are missing.

As a result, they accumulate throughout the body, consuming oxygen and nutrients meant for other cells.

Cancerous cells can form tumors, impair the immune system and cause other changes that prevent the body from functioning regularly. Cancerous cells may appear in one area, then spread via the lymph nodes. These are clusters of immune cells located throughout the body.


There are many causes of cancer, and some are preventable.

For example, over 480,000 people die in the U.S. each year from smoking cigarettes, according to data reported in 2014.

In addition to smoking, risk factors for cancer include:

  • Heavy alcohol consumption
  • Excess body weight
  • Physical inactivity
  • Poor nutrition

Other causes of cancer are not preventable. Currently, the most significant unpreventable risk factor is age. According to the American Cancer Society, doctors in the U.S. diagnose 87 percent of cancer cases in people ages 50 years or older.

Is cancer genetic?

Genetic factors can contribute to the development of cancer. A person’s genetic code tells their cells when to divide and expire. Changes in the genes can lead to faulty instructions, and cancer can result.

Proteins carry many of the instructions for cellular development and division, and genes have an impact on their creation.

Some genes alter proteins that are normally involved in cell repair. This has the potential to cause cancer. If a parent carries these genes, their offspring may inherit the changed instructions.

After birth, some genetic alterations can occur, and factors like smoking and sun exposure might enhance the risk.

Other changes that can lead to cancer occur in the chemical signals that control how the body “expresses” or deploys specific genes.

Finally, a person can be born with a cancer predisposition. Hereditary cancer syndrome is a term used by doctors to describe this condition.

Inherited genetic mutations significantly contribute to the development of 5–10 percent trusted Source of cancer cases.


Innovative research has fueled the development of new medications and treatment technologies.

Doctors usually prescribe treatments based on the type of cancer, its stage at diagnosis, and the person’s overall health.

Below are examples of approaches to cancer treatment:

  • Chemotherapy uses drugs that target quickly dividing cells to kill malignant cells. The medications can also help reduce tum, but they can have serious negative effects.
  • Hormone therapy entails taking drugs that alter the way particular hormones act or prevent the body from producing them. This is a typical technique when hormones play a substantial role, such as in prostate and breast malignancies.
  • Immunotherapy is a type of treatment that boosts the immune system and encourages it to fight malignant cells by using drugs and other treatments. Checkpoint inhibitors and adoptive cell transfer are two examples of this therapy.
  • Precision medicine, often known as personalized medicine, is a relatively recent concept. It entails employing genetic testing to discover the most effective treatments for a person’s specific cancer presentation.
  • However, researchers have yet to show that it is helpful in treating all types of cancer.
  • High-dose radiation is used in radiation therapy to eliminate malignant cells. A doctor may also suggest that radiation be used to decrease a tumor before surgery or to alleviate tumor-related symptoms.
  • People with blood-related malignancies, such as leukemia or lymphoma, may benefit from a stem cell transplant. It entails eliminating cells that have been damaged by chem otherapy or radiation, such as red or white blood cells. The cells are then strengthened and reintroduced into the body by lab technicians.
  • When a person has a malignant tumor, surgery is frequently part of the treatment approach. A surgeon may also remove lymph nodes to slow or stop the disease from spreading.
  • Targeted therapies perform functions within cancerous cells to prevent them from multiplying. They can also boost the immune system. Two examples of these therapies are small-molecule drugs and monoclonal antibodies.

Doctors will often employ more than one type of treatment to maximize effectiveness.


The most common type of cancer in the U.S. is breast cancer, followed by lung and prostate cancers, according to the National Cancer Institute, which excluded nonmelanoma skin cancers from these findings.

Each year, more than 40,000 people in the country receive a diagnosis of one of the following types of cancer:

  • bladder
  • colon and rectal
  • endometrial
  • kidney
  • Leukemia
  • liver
  • Melanoma
  • Non-Hodgkin’s lymphoma
  • pancreatic
  • thyroid

Other forms are less common. According to the National Cancer Institute, there are over 100 types of cancer.

Cancer development and cell division

Doctors classify cancer by:

  • its location in the body
  • the tissues that it forms in

For example, sarcomas develop in bones or soft tissues, while carcinomas form in cells that cover internal or external surfaces of the body. Basal cell carcinomas develop in the skin, while adenocarcinomas can form in the breast.

When cancerous cells spread to other parts of the body, the medical term for this is metastasis. A person can also have more than one type of cancer at a time. To discover more evidence-based information and resources for cancer, visit our dedicated hub.


Improvements in cancer detection increased awareness of the risks of smoking, and a drop in tobacco use have all contributed to a year-on-year decrease in the number of cancer diagnoses and deaths.

According to the American Cancer Society, the overall cancer death rate declined by 26 percent between 1991 and 2015.

When a person has cancer, the outlook will depend on whether the disease has spread and on the type, severity, and location of cancer.


Cancer causes cells to divide uncontrollably. It also prevents them from dying at the natural point in their life cycle.

Genetic factors and lifestyle choices, such as smoking, can contribute to the development of the disease. Several elements affect the ways that DNA communicates with cells and directs their division and death.

Breast cancer is the most common type of cancer in the U.S. after non-melanoma skin cancer. However, lung cancer is the leading cause of cancer-related death.

Treatments are constantly improving. Examples of current methods include chemotherapy, radiation therapy, and surgery. Some people benefit from newer options, such as stem cell transplantation and precision medicine.

The diagnosis and death rates of cancer are dropping yearly.

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