Overview

Cancer is an umbrella term for a large group of diseases in the body due cancerous cells. It happens when cells of the body divide uncontrollably. Abnormal division of cells can result in tumors, damage to the immune system, and other impairment that can be fatal. Cancer can be a group of more than 100 different diseases and develop almost anywhere in the body. According to the American Cancer Society, more than 15.5 million cases reported that were infected from different types of cancer in the United States. This article examines different types of cancer, their treatments, risk factors, causes, and survival rate.

How cancer arises in the Human Body?

Cancer is the second most leading death reason in the world. Although, the survival ratio is improving with time due to effective testing and medication.

Cells are the basic unit of the human body. Cells grow and divide into new cells as the body needs them. It is an orderly process of production and damaging of cells. Cells die when it came to their specific age and get old or damage.

Cancer begins when the order process of cells disturb due to genetic changes. Cells start to grow uncontrollably and form a mass term as a tumor. This tumor can be cancerous or benign. A cancerous cell has the malignant ability to grow and spread to other parts of the body. Contrary to cancerous cells, a benign tumor can grow but cannot spread.

Some types of cancer do not form a tumor. These include leukemias, most types of lymphoma, and myeloma.

Four Main Types of Cancer

Cancer Specialists categorize cancer based on where it begins. There are four main types of cancer.

1. Carcinomas

A carcinoma begins from the tissues of organs and covers the surface of internal organs and glands. In simple words, it starts in the skin of the organs. Prostate Cancer, Breast Cancer, Lung cancer, and colorectal cancer are examples of carcinomas.

2. Sarcomas

Cancerous cells that begin in the tissues that support and connect the body known as Sarcomas. However, there are more than 50 types of sarcoma. But it can be categorized into two main types: soft tissue sarcoma and bone sarcoma (Osteosarcoma). It can develop in fat, muscles, nerves, tendons, joints, blood vessels, lymph vessels, cartilage, or bone. According to reports, more than 12,750 cases of soft tissue sarcoma and 800-900 cases of bone sarcoma were reported in the just USA in 2019.

3. Leukemias

Blood cancer is also known as Leukemia. It begins in the Bone Marrow due to the change in the healthy blood cells with uncontrollable growth. The blood cells that are not fully developed are called Blasts or Leukemia cells. Leukemia has further categorized four types: Acute Lymphocytic Leukemia, Chronic Lymphocytic Leukemia, Acute Myeloid Leukemia, and Chronic Myeloid Leukemia.

4. Lymphomas

Lymphomas are cancer that begins in the lymphatic system. The lymphatic system is a network of vessels and glands that helps fight infection. There are two main types of Lymphomas: Hodgkin Lymphoma and non-Hodgkin lymphoma.

5. Multiple Myeloma (Plasma cell Myeloma)

A type of cancer that originates from the plasma cells. In addition to white blood cells, Plasma cells are another type of immune cell. Myeloma cells are abnormal plasma cells. These cells originate in the bone marrow and form tumors in the bones of the whole body. This disease is also famous from the name Kahler disease.

6. Melanoma

This type of cancer starts to produce in the cells that become Melanocytes. Melanocytes are the cells that are responsible to make melanin; a pigment that gives color to the skin. These cells are not limited to melanin but also can form in the pigmented tissues, such as the eyes.

7. Brain and Spinal Cord Tumor

Brain and spinal cord tumors have different types based on the type of cells in which they produce and where the tumor first formed in the central nervous system. A brain tumor can be malignant or benign.

8. Other Types of Tumors

• Germ cell tumors

Germ cell tumors are a type of tumor that begins in the cells that give rise to sperm or eggs. These tumors can occur almost anywhere in the body and can be either benign or malignant.

• Neuroendocrine tumors

Neuroendocrine tumors form from cells that release hormones into the blood in response to a signal from the nervous system. This type of tumor can be malignant or benign.

• Carcinoid tumors

A type of neuroendocrine, a slow-growing tumor, originates often in the gastrointestinal system. Mostly found in the rectum and small intestine. These tumors may spread to the liver or other sites in the body.  they may be created substances like serotonin or prostaglandins. These substances can cause carcinoid syndrome.

Symptoms of Cancer

Signs and symptoms of cancerous infection in the body can be vary depending on the body part that is affected. Some general signs and symptoms of cancer are:

• Fatigue
• Thickening of the area or lump under the skin
• Abnormal weight changes
• Changes in the skin like yellowing, darkening, or redness of the skin, or changes in the existing moles
• Changes in the bowel or bladder habits
• Trouble in breathing
• Lasting cough
• Difficulty in Swallowing
• Hoarseness
• Consistent stomach disorder or discomfort after eating
• Unexplained and constantly muscle and joint pain
• persistent, unexplained fevers or night sweats
• Abnormal bleeding or bruising

What are the Causes of Cancer?

Cancer is caused by changes (mutations) to the DNA within cells. DNA consists of a vast number of individual genes, and each gene consists of a set of instructions. These instruction commands the cells what function to perform and how to grow and divide. Cells turn into normal to cancerous due to errors in instructions. Cells stop their regular operation, and it causes make it cancerous.

What do gene mutations do?

A gene mutation can instruct a healthy cell to:

• Allow rapid Growth: A gene mutation can tell a cell to grow and divide more rapidly. As a result, many new cells can create that all have the same mutation.
• Fails to control Cells Growth: In the normal growth of cells, genes have instructions on when to stop cells’ growth. But due to gene mutation, cancer cells lose the control of Tumor Suppressor gene, which tell them when to stop the growth of cells. A mutation in the Tumor Suppressor gene allows cancer cells to continue growing and accumulating.
• Errors in DNA Repairing: DNA repair genes look for errors in a cell’s DNA and correct any abnormalities found. A mutation in a DNA repair gene can retain the mistakes in the DNA, leads to becoming cancerous cells.

These mutations are the most common ones found in cancer. But many other gene mutations can contribute to causing cancer.

What causes gene mutations?

Many reasons can cause mutations in the gene. Some are discussed below:

• Inherited Gene Mutation: You may bear with some gene mutations inherited from your parents. This type of mutations can produce a small percentage of cancers.
• After Birth Gene Mutation: Mostly, gene mutations resulting in cancerous cells’ growth are not inherited. Many elements can mutate the genes, such as smoking, radiation, viruses, cancer-causing chemicals (carcinogens), obesity, hormones, chronic inflammation, and a lack of exercise.

How do gene mutations interact with each other?

Cancer is the result of the interaction of both gene mutation that you acquire after birth and hereditary. For instance, if you have an inherited gene mutation that predisposes you to cancer, that doesn’t mean to get cancer. According to different tests, you may need more than one gene mutations to cause cancer. It is possible to get more chances to develop cancer of those who acquire inherited gene mutation than others. It is not confirmed how much gene mutation can cause cancer. It can vary among cancer types.

What are the Risk Factors of Cancer?

By analyzing different tests and statistical data, doctors trying to give an idea of factors that can increase the risk of cancer. It is important to note that, majority of people diagnosed with cancer without these risk factors. It is an idea that these factors can play their role in the development of cancerous cells. Factors are known to increase the risk of cancer include:

Age:

Most people diagnosed with cancer are 55 years or older than that. According to studies, cancer can take several years to develop. But, it is not evident that cancer can’t be diagnosed in adults. In comparison, it is more common in old adults. In short, cancer can be diagnosed at any age.

Habits:

Lifestyle choices create a profound impact on your health. Confident lifestyle choices are known to increase your risk of cancer. Smoking, Drinking Alcohol, excessive exposure to direct sunlight, being obese, and, most important having unsafe sex can enhance the risk of cancer. Everybody must change their habits to lower their risk of cancer. Although, these habits are easies to change.

Family History

According to statistics, persons that are affected from cancer due to inherited condition is the minimal number. It is possible to transfer a mutated gene from one generation to another, but it is not evident that person will be sure affected from cancer if the mutated gene is inherited. You should check the gene mutation test to see whether you have an inherited mutation or not. It is possible to increase the risk of cancer of inherited mutated gene person than others.

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.

Environment

The surrounding environment may create an impact on the risk of cancer if your surrounding environment may contain toxic and harmful chemicals. It can definitely elevate the risk of cancer. Even if you do not smoke, but you are inhaling secondhand smoke if you where people are smoking or you live with the person that adequately smokes. Chemicals in your home or workplace, such as asbestos and benzene, also are associated with an increased risk of cancer.

Complications in Cancer

While advances in both the treatment of cancer and the management of its complications have led to significant improvement in patient survival, infections remain a significant cause of morbidity and mortality in patients with neo plastic disease. In this patient population, infection risk results from a complex interplay between the host’s underlying immunodeficiencies, local tumor effects and treatment-induced immunosuppression.

New chemotherapeutic approaches and antimicrobial prophylaxis and treatment practices continue to shape the spectrum of infections in these patients. Clinicians who treat infections in cancer patients are continually challenged by the emergence of new pathogens and by the increasing antimicrobial resistance of established ones.

Cancer and its treatment can cause several complications, including:

• Pain. Treatment of cancer is mostly painful. Chemotherapy, Laser treatment on tumours have painful after-effects. However, all cancers are not painful. Medications and many other approaches help out effectively in the treatment of cancer-related pain.
• Fatigue. Many people face fatigue due to chemotherapy or radiation therapy treatments. The fatigue can be due to many reasons but usually temporary.
• Difficulty breathing. Highlighted problem after cancer treatment is the difficulty in breathing. The patient can feel the shortness of breath. Treatments may bring relief.
• Nausea. Certain cancers and cancer treatments can cause nausea. Your doctor can sometimes predict if your treatment is likely to cause nausea. Medications and other therapies may help you prevent or decrease nausea.
• Diarrhea or Constipation. Cancer and cancer treatment can affect your bowels and cause diarrhoea or constipation.
• Weight loss. Cancer and cancer treatment may cause weight loss. Cancer steals food from normal cells and deprives them of nutrients. This is often not affected by how many calories or what kind of food is eaten; it’s challenging to treat. In most cases, using artificial nutrition through tubes into the stomach or vein does not help change the weight loss.
• Chemical changes in your body. Cancer can upset the normal chemical balance in your body and increase your risk of serious complications. Signs and symptoms of chemical imbalances might include excessive thirst, frequent urination, constipation and confusion.
• Brain and nervous system problems. Cancer can press on nearby nerves and cause pain and loss of function of one part of your body. Cancer that involves the brain can cause headaches and stroke-like signs and symptoms, such as weakness on one side of your body.
• Unusual immune system reactions to cancer. In some cases, the body’s immune system may react to the presence of cancer by attacking healthy cells.

How to reduce your Risk of Cancer?

Doctors have identified several ways to reduce your risk of cancer, such as:

• Stop smoking.
• Avoid excessive sun exposure.
• Eat a healthy diet.
• Exercise most days of the week.
• Maintain a healthy weight.
• Drink alcohol in moderation if you choose to drink.
• Schedule cancer screening exams.
• Ask your doctor about immunizations.

Stages of Cancer

Due to genetic mutations, we already know that the tumor suppressor gene deactivated and lose its ability to control the growth of cells that are not necessary for the body. The uncontrolled growth of cells leads to the formation of a tumor. With time, different changes occur during the evolution of tumor cells, from a normal cell to an initially benign growth to a malignant metastatic tumor that threatens a patient’s life.

Staging helps the doctor to describe where cancer is located. From the diagnostic tests, the condition of the tumor can be determined, whether it is affecting the other parts of the body. Treatment is decided by the doctors done based on diagnostic tests and staging of cancer. That’s the reason it is very important to know bout the staging of cancer. Knowing the stage helps the doctor:

• Plan treatment, including the type of surgery and/or whether Chemotherapy or Radiation Therapy are needed.
• Predict the chances of recovery after treatment
• Discuss the case with the entire cancer specialist team
• Predict the after treatment complication

Evolution of Cancer Cells

The growth of a tumor can be thought of as an evolutionary process. Our bodies have several controls that restrict abnormal growth, and each of these must be overcome by the cancer cell in the progression toward malignancy. Malignant tumors contain many genetic alterations, but these don’t all happen at once. The mutation can activate a proto-oncogene or inactivates a tumor suppressor gene. Next, the division of that mutated cell leads to producing a clone of cells within the tissue. After some time, one cell in this clone may sustain another mutation, which allows it to grow faster than its neighbors that carry only a single mutation. Double mutant cells can grow faster, which drives the evolutionary changes observed in cancer progression.

Each of these genetic changes leads to a progressive alteration in the appearance and behavior of the tumor cells. The cellular changes of tissues can be seen in tissue samples using a microscope. The following category based on cellular changes of tissues is as follows:

Hyperplasia: 

 The earliest detectable alteration in tissue structure is hyperplasia (excessive growth). Hyperplasia is a precancerous state that might or might not ever become cancer. It is characterized by an increased number of cells still very similar in shape and organization to normal cells. Hyperplasia may or may not result from a cellular mutation. It can also be a response to inflammation in the tissue or some other stress. For example, the patch of toughened skin (callus) that can build up on your hand when you start to play tennis is hyperplasia. Obviously, tennis does not cause cancer, and the callus will go away with time. Therefore, hyperplasia is not an irreversible state, and the tissue can often return to normal without further consequences.

Dysplasia: 

The next stage of cancer development, which can arise from hyperplasia, is called dysplasia. The cells have begun to lose the normal orderly arrangement and appearance found in normal and hyperplastic tissues. Dysplastic cells may divide more rapidly than their hyperplastic precursors, and they also share some of the properties of malignant cells. They often have relatively large and irregularly shaped nuclei, a feature that can aid in a pathologist’s diagnosis. Like hyperplasia, dysplasia is an abnormal growth that is not yet cancer. It may return to normal (regress), persist without significant changes, or accumulate further changes leading to malignancy.

Carcinoma in situ: 

Carcinoma in situ is an advanced state of dysplasia, but it is still not malignant. In carcinoma in situ, the dysplastic cells have expanded, and few normal cells remain. Nevertheless, this colony of abnormal cells is still surrounded and constrained by a basement membrane. There are no blood vessels (or lymphatics) inside the carcinoma in situ, as they too are separated from the basement membrane’s growth. Consequently, cells from carcinoma in situ cannot metastasize (spread) to other body areas, which is crucial because if surgery can remove cancer before it spreads, the chances of recovery are usually very good.

Invasive Cancer: 

Hyperplasia, Dysplasia and Carcinoma in situ are generally not life-threatening. They are distinguished from malignant lesions by lack of invasion into the surrounding tissue. The acquisition of the ability to invade surrounding tissue is the crucial threshold that divides nonmalignant (benign) from malignant tumors. Surgical removal of benign tumors, if detected early, is often straightforward, and the patient will often make a full recovery. Once a tumor has become invasive cancer, the patient and doctors are confronted with a range of problems not seen in benign disease. If cancer has spread to other parts of the body, it becomes very difficult to cure.

Metastatic Cancer: 

Once cancer has developed the ability to break down the basement membrane and invade surrounding tissues, it will often begin to spread to other parts of the body. This process is called metastasis. Cells often spread first to nearby lymph nodes and then to other parts of the body. Colonies of cancer cells can become established in distant organs and begin to grow. In most cases, these colonies are called metastases, which will ultimately cause death from cancer as they disrupt the function of the organs that the body needs to survive.

Benign tumors are usually smooth around the edges and are separated from nearby normal tissues by the basement membrane. To become invasive, this basement membrane, which is made of proteins, must be broken down. Tumor cells produce many enzymes, called proteases, which degrade proteins. Production of these enzymes allows the tumor cells to degrade the basement membrane. When the basement membrane is disrupted in this way, there is no longer an effective barrier to keep the cancer cells in place. The cells can then start to migrate out of the tumor. When an invasive tumor is examined under the microscope, it is often irregularly shaped, rather than smooth, at the edges. It is possible to see the tumor cells migrating away (See in the figure) from the primary tumor. Once the basement membrane has been broken down and the tumor cells begin to invade the nearby normal tissues, the cancer is considered malignant and a threat to the patient’s life.

TNM Staging System of Cancer

The most used system for most of the cancer types, the TNM system of the American Joint Committee on Cancer (AJCC), describes cancer’s stage. After complete diagnostic tests, doctors answer the following question based on tests and after taking a sample of the tumor or complete removal after surgery.

• Size of the primary tumor? (Tumor, T)
• Location of Tumor in the body?
• How much tumor spread to the lymph nodes and their location? (Node, N)
• Did cancer spread to the other parts of the body? (Metastasis, M)

Staging can be “Clinical” or “pathological”. Clinical staging is based on the tests before surgery, such as physical examination and imaging scans. Pathological staging is based on what is found during surgery.

Most of the time, it is staging done after a person received prerequisite treatments before surgery like chemotherapy, Radiation Therapy, or Immunotherapy. This is called post-therapy surgery. The TNM staging can be done for some type of cancer. Before surgery, treatment helps the tumor shrink so that it can easily be removed.

The Clinical Stage is often indicated with lowercase “c,” the Pathological Stage if often indicated with lowercase “p”, and Post therapy is often indicated with lowercase “v” before TNM Staging System.

TNM Description:

In this section, the general description of the TNM Staging is listed. It is important to note that the describe definitions are different for different types of cancer using the TNM Staging System. Learn about the general staging information for each type of cancer.

• Tumor (T): The letter “T” range (0-4) indicated the size and location of the tumor. Tumor size is measured in centimeters (cm). The deeper and larger the tumor size, the more will be the number of “T”. For more details in “Tumor”, lowercase letters “a”, “b”, or “m” are added to the “T” category to provide more details.
• Node (N):  The letter “N” range (0-4) is used for lymph nodes. Lymph nodes near the cancer cells know as Regional Lymph nodes. At the same time, lymph nodes in other parts of the body are called Distant Lymph nodes. More lymph nodes near the cancerous tumor, the larger the number assigned to the “N” category.
• Metastasis (M). The letter “M” indicates whether cancer has spread to other parts of the body, called distant metastasis. If cancer has not spread, it is labeled M0. If cancer has spread, it is considered M1.

Cancer Stage Grouping

Doctors combine the T, N, M results and other factors specific to cancer to determine the stage of cancer for each person. Most types of cancer have four stages: stages I (1) to IV (4). Some cancers also have a stage 0 (zero).

• Stage 0. This stage describes Carcinoma in situ, which means “in place.” Stage 0 cancers are still located in the place they started and have not spread to nearby tissues. This stage of cancer is often highly curable, usually by removing the entire tumor with surgery.
• Stage I. This stage is usually small cancer or tumor that has not grown deeply into nearby tissues. It also has not spread to the lymph nodes or other parts of the body. It is often called early-stage cancer.
• Stage II and Stage III. In general, these two stages indicate larger cancers or tumors that have grown more deeply into nearby tissue. They may have also spread to lymph nodes but not to other parts of the body.
• Stage IV. This stage means that cancer has spread to other organs or parts of the body. It may also be called advanced or metastatic cancer.

Summary

Tumors evolve from normal cells by acquiring and accumulating mutations over time, leading to progressively disordered tissue architecture and rapid growth. Tumors are considered benign until they develop the ability to invade surrounding tissues. At this stage, metastasis to other parts of the body is a real danger. The pathologist plays a very important role in examining the tumor and determining the prognosis of the disease.