What Is Cancer? Symptoms, Causes, Diagnosis and Treatment

The word " cancer " instills terror in many people, and it remains one of the most misunderstood terms. Although many individuals will experience cancer at least once in their lifetime, most people know very little about cancer beyond the basic definition of it: uncontrolled growth of cells. Indeed, there is a lot more than just a simple definition to know about cancer, and knowing what cancer is, why it happens, how it acts, and how medicine tries to combat it can be the difference between a scared decision and an informed one, either when doing research for oneself or for somebody close.

This blog attempts to explain everything there is to know about cancer, starting from biology and ending with ways to treat and prevent it.

What is Cancer?

Cancer refers to a large number of diseases in which cells grow out of control and can spread within the body. Normally, the cells in the body follow a specific pattern of growth and division in order to produce new cells to maintain health. This process is known as cell division, and occurs under the guidance of genetic information stored in the cells. When something disrupts these instructions, cells can begin to grow and divide without the usual checks — and, critically, without dying when they're supposed to.

Such defective cells form an abnormal mass of cells are known as a tumor. Tumors can either be malignant or benign. While a benign tumor does not invade the surrounding tissues and remains localized, a malignant tumor spreads into the surrounding tissues and also spreads to other parts of the body in a process known as metastasis.

There are over 100 different forms of cancer. Although there are significant differences between the various types of cancers, in terms of behavior and treatment, they all share a common underlying feature: uncontrolled growth of cells.

How Cancer Develops: The Biology Behind It?

The process of cancer starts with alterations in cells due to mutations, which are changes in DNA, which is the blueprint for the functioning and multiplication of cells.

Most mutations are benign or are corrected automatically within the cell. However, there are times when mutations occur in specific genes that control the multiplication of cells. There are basically three types of such genes:

Oncogenes, which are responsible for accelerating cell growth.
Tumor suppressor genes, which act as regulators of cell growth, slowing it down or even initiating cell death when there are problems in the cells.
DNA repair genes, which correct mutations in DNA.

It is rare that a single mutation will be responsible for the development of cancer. Several mutations are required to occur over a period of years before a cancer develops. This is one of the reasons why the incidence of cancer increases with age because more time has been given to the body to develop cancer mutations.

When the cell is finally cancerous, it can replicate and become a tumor. The tumor can then use the lymph system and the blood system to transport cancer cells to another organ in the body to form new tumors. This spread — metastasis — is what makes cancer particularly dangerous and is often the point at which treatment becomes more complex.

What Causes Cancer?

Cancer is not due to one particular cause. Cancer is due to a number of risk factors such as genetics, environment, and behavior which lead to damaging of DNA and disruption of cell regulation. Some of these risk factors include:

1. Genetics and Heredity: People can inherit a mutation in their genes which increase their risk of cancer development. Mutation in the BRCA1 and BRCA2 genes for instance increases one's risk of getting breast and ovarian cancer. However, the percentage of cancer inherited genetically is 5-10%. The rest is caused by mutations that occur during the person's lifetime and are not inherited.

2. Smoking: Smoking is the single most preventable cause of cancer which has been identified as one of the leading causes of lung, throat, mouth, esophageal, bladder, and pancreatic cancers. Smoke contains many known carcinogens which have the ability to cause cancer.

3. Poor diet and physical inactivity: Poor diets especially those with a lot of processed foods, lack of fruits and vegetables, and low fiber foods increase the risk of developing colorectal cancer. Physical inactivity and obesity has been identified to increase the risk of at least 13 cancers.

4. Alcohol Intake: Alcohol is regarded as a Group 1 carcinogen; this means that it is strongly connected with cancer in human beings, and is known to cause mouth, throat, liver, breast, and esophageal cancers.

5. Radiation: Radiation from ultraviolet light of the sun is the main cause of skin cancer. On the other hand, high-dose ionizing radiation during medical imaging, as well as occupational radiation, might also be a factor in developing cancer.

6. Infection: Cancer may also be caused by certain infections, such as:

Human papillomavirus (HPV), which is associated with cervical, throat, and anal cancer.
Hepatitis B and C, which may lead to liver cancer.
Bacterial infection called Helicobacter pylori (H. pylori) causes stomach cancer.

7. Environmental/Occupational Factors: Being exposed to different chemicals, such as asbestos, benzene, and other carcinogens found in the workplace environment, raises the risk of developing different types of cancers, especially lung and blood cancers.

It is important to highlight that even with having a risk factor, it does not mean that one will inevitably have cancer, as in most cases, cancer patients do not have any known risk factors.

Types of Cancer

Cancer can be characterized on the basis of the type of cell from which it starts:

Carcinomas: The most common type of cancer that begins in skin or tissues covering internal organs (such as breast cancer, lung cancer, prostate cancer, or colon cancer).
Sarcomas: Start in bones, muscles, fat, blood vessels, or other connective tissue.
Leukemias: Cancers that start in blood forming tissues like bone marrow and lead to the formation of abnormal blood cells.
Lymphomas: Cancer that starts in immune cells known as lymphocytes.
Myelomas: Cancer starting in plasma cells, an immune cell in bone marrow.
Central nervous system cancers: These start in brain or spinal cord.

The types of cancer that are most frequently diagnosed across the globe include breast cancer, lung cancer, colorectal cancer, prostate cancer, and skin cancer. Lung cancer continues to be the most common cause of death due to cancer due to its association with smoking and late diagnosis.

Symptoms of Cancer

The symptoms of cancer differ widely based on the specific kind and location of cancer, and many early stages of cancer produce absolutely no symptoms, hence the importance of screening. That being said, there are some general symptoms that require medical attention:

Weight loss
Fatigue
Unexplained lumps or swelling
Skin changes (appearance of new moles or sores that don't heal)
Cough or hoarseness
Changes in bowel or bladder habits
Difficulties swallowing
Unexplained bleeding or discharge
Persistent pain for unknown reasons.

None of these symptoms indicate cancer on their own — they are usually caused by something completely harmless. Still, any of these symptoms that are unexplained and persistent should be discussed with a doctor because early diagnosis makes a big difference in cancer treatment in almost every case.

How Cancer is Diagnosed?

Cancer is generally diagnosed through:

1. Physical Examination: The doctor looks for lumps or any other physical indication of cancer.

2. Imaging Tests: Imaging devices such as CT scan, MRI, X-ray, PET scan, and ultrasound imaging tests provide a picture of internal structures and abnormal growths.

3. Laboratory Tests: Laboratory tests like blood test, urine test, and tumor marker tests may reveal any abnormality associated with particular types of cancers; however, these tests alone cannot diagnose cancer.

4. Biopsy: The removal of a piece of tissue from the body to observe it under a microscope is the only method by which cancer is diagnosed. The pathologists check the cells for their nature of being cancerous or not and what kind of cancer it is if it is cancer.

5. Genetic and Molecular Tests: With recent advancements in medical science, genetic testing of cancerous tissues is becoming common in order to know the particular mutations responsible for causing cancer.

Understanding Cancer Staging

Once a diagnosis is made, a staging process usually follows that provides information on the spread of the cancer in the body. Staging aids in making decisions about cancer management and also gives a general idea on the prognosis. One of the systems used globally for staging cancers is the TNM system:

T – size of the primary tumor
N – cancer spread to the lymph nodes near the primary tumor
M – cancer spread to distant sites from the primary tumor.

Usually, cancer is staged as stages 0 through 4:

Stage 0 – presence of abnormal cells that have not become cancerous (carcinoma in situ)
Stage 1 – localized and limited growth of cancer
Stage 2–3 – increased growth and spread of cancer to nearby tissues and lymph nodes
Stage 4 – distant spread of cancer (metastasis).

In general, early stages of cancer are associated with better outcomes of treatment, which explains the focus on early detection and screening programs.

Cancer Treatment Options

Treatment methods depend on the type of cancer, stage of disease, its localization, and the general condition of the patient. Most of the treatment plans involve combination of several methods listed below:

1. Surgery: Tumor removal together with adjacent tissues remains the first method to fight localized and solid tumors.

2. Chemotherapy: This method involves use of drugs that kill rapidly dividing cells all over the body. This method proves efficient when it comes to various types of cancer but at the same time influences dividing healthy cells causing such side effects as hair loss, exhaustion, and nausea.

3. Radiation Therapy: This method uses high energy rays that damage DNA of cancer cells with an aim to shrink tumors before surgery or destroy residual cancer cells after surgery.

4. Immunotherapy: Immunotherapy includes strengthening of the organism's own immune system that recognizes and destroys cancer cells. It is one of the newest and most promising fields in cancer treatment that has helped to improve the results in treatment of certain kinds of cancer, namely melanoma and some lung cancers.

5. Targeted Therapy: Contrary to chemotherapy, targeted therapy drugs affect only genes or proteins that cause cancer growth.

6. Hormone Therapy: It is mostly used in hormone-sensitive cancers such as breast and prostate cancer by interfering with or reducing the hormones that help the tumor grow.

7. Bone Marrow or Stem Cell Transplant: Bone marrow transplant is usually used in blood cancers such as leukemia and lymphoma, where bone marrow is replaced by stem cells.

Cancer treatments are becoming more individualized depending on the genetic makeup of the tumor rather than a generalized treatment plan.

Cancer Prevention: What Actually Reduces Risk

Even though not all cancers are preventable, scientific research proves that a large percentage of cancer patients have their disease caused by modifiable risk factors. Scientifically proven measures for preventing cancers include the following:

Avoiding tobacco in all forms
Limiting alcohol consumption
Maintaining a healthy weight through diet and physical activity
Protecting skin from UV exposure with sunscreen and protective clothing
Getting vaccinated against HPV and Hepatitis B
Attending recommended cancer screenings (mammograms, colonoscopies, Pap smears, etc.)
Limiting exposure to known carcinogens in occupational or environmental settings.

According to the World Health Organization, at least 30-50% of cancer cases are preventable with risk factor modification and available preventive measures.

Living With Cancer: Beyond the Diagnosis

The problem of cancer goes way beyond the physical body, and includes mental well-being, interpersonal relations, finances and the everyday routine of an individual. Contemporary oncology pays more attention to supportive care that includes:

Symptom management
Nutritional care
Counseling on psychological issues
Palliative care for those with an advanced stage of the disease
Programs aimed at survival and follow-up.

Thanks to early detection, better diagnostics and treatment methods, the survival rate for cancer has increased dramatically in recent decades. There are many types of cancer which used to be absolutely deadly and now have five-year survival rates of 80-90%.

Common Myths About Cancer

There are many misconceptions surrounding cancer. Just some important clarifications:

Cancer is not necessarily deadly. There is enormous variability in survival rates depending on cancer type and stage, and many types of cancer are very treatable.
Cancer is not contagious. It is not something you can "catch" from another individual; however, there are cancer-causing infections that can be passed between people.
Sugar does not directly "feed" cancer in the way that it is often said to do in the media. Although all cells, including cancerous cells, consume glucose as an energy source, eliminating sugar will not "starve" a cancer because cancer cells can get their energy from elsewhere.
Not all cancers need to be aggressively treated. Some forms of slowly progressing cancer are managed through observation only.

Final Thoughts

Cancer does not refer to a specific disease but rather a group of diseases characterized by the same basic mechanism: uncontrolled cell growth due to genetic mutation. Learning about the biology, risks, and treatment of the disease will do more than satisfy one's curiosity; it may allow better decision-making about screening, risk reduction, or expectations in the event of a diagnosis.

Developments in the fields of genomics, immunology, and early detection are changing the meaning of a cancer diagnosis. No longer is it considered a blanket death sentence for those who receive such a diagnosis.

If you or your loved ones show signs of possible cancer, the best course of action is clear: see a doctor. Early diagnosis continues to be one of the best weapons in the battle against cancer.