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CANCER OVERVIEW

Picture this. A friend or relative calls you one day, you can hear the panic and sadness in their voice. They inform you, they are at the hospital where a doctor has just told them they have cancer. But what exactly is cancer and why is it such a feared condition?

Cancer is defined as a disease caused by uncontrolled or abnormal growth of cells in any part of the body.

These abnormal cells have the potential to spread (i.e. invade) other body parts of the body close to or far away from the cancer’s site of origin.

To fully grasp the concept of cancer, it is best to understand where the abnormal cells come from and why. The abnormal cell growth is due to an imbalance in the management of the body’s new cell formations and old cell destruction or death (apoptosis).

Cancer is different from the other types of tumors because of its malignancy; its ability to invade or spread to other body parts. In contrast, a benign tumor does not invade or spread to other tissues.

CLASSIFICATION OF CANCERS

Cancers are usually grouped based on the type of cell that undergoes abnormal proliferation or growth and the cancer cells usually resemble the normal cells they originate from.

  • Carcinomas:

    These cancers are of the epithelial origin (cells that cover surfaces of organs and tissues). These include cancers of the skin, lungs, breasts, and pancreas. Carcinomas are the most commonly diagnosed cancer.

  • Sarcomas:

    This cancer type originates from mesenchymal cells; cells that will divide to become a number of other different cells. Cancers of the bone, fat cells, cartilages, muscles, and blood vessels all fall under this category.

  • Lymphomas:

    Cancers that affect the blood cells in the lymphatic system. This includes cells of various lymphatic organs like lymph nodes, thymus, spleen and bone marrow. The cells typically affected in this type of cancer are the white blood T and B cells.

  • Leukemia:

    Cancer that starts in the “blood cell-producing” bone marrow. It is characterized by overproduction of white blood cells that are inefficient at fighting infections.

  • Melanomas:

    Cancers of the melanocytes; cells that produce the pigment responsible for dark skin, melanin.

  • Blastomas:

    Cancers of immature undifferentiated cells or blast cells (precursor or stem cells). These are cells that have not divided and taking on a unique function yet.

METASTASIS

This refers to the spread or invasion of the cancer cells to other parts of the body from the site they originally formed. The routes of transport or spread of cancer cells are:

  • Direct invasion:

    Where the cancer can spread to nearby tissues due to its proximity or closeness to them.

  • Hematogenous spread:

With the cancer spreading or traveling through blood vessels to other parts of the body.

  • Lymphatic spread:

    Spreading through lymph vessels and lymph nodes to other parts of the body.

Both hematogenous and lymphatic metastasis of cancer are considered an indirect invasion. They make use of vessels to travel far from the origin of cancer cells without directly invading neighboring tissues and organs.

I don’t want to die until I see cancer cured.“- James D. Watson

CAUSES (ETIOLOGY)

It is impossible to determine the main cause of cancer but the hallmark of every cancer is a genetic mutation. A genetic mutation is an alteration or change in the normal structure of a gene resulting in abnormal cell growth and the inability to control said growth. Gene mutation is mostly due to environmental factors and to a lesser extent, inheriting “faulty” genes.

  • Environmental factors

    (90-95%): This accounts for a majority of cancer-related cases.

Tobacco (25-30%)

Diet and obesity (30-35%)

Infection (15-20%)

Radiation (10%)

Stress, lack of physical exercise, hormones and pollution.

  •  Inherited genetics (5-10%)

EPIDEMIOLOGY

An estimation of about 9.8 million deaths and 18.1 million new cases of cancer were documented globally in 2018 by the World Health Organization (WHO). Males are more susceptible to developing cancer as compare to females with respect to lifestyle as a breach of environmental factors as discussed earlier. Lung, prostate, colorectal, stomach and liver cancer are the most common types of cancer in men, while breast, colorectal, lung, cervix and thyroid cancer are the most common among women. The three most common childhood cancers are leukemia, brain tumors, and lymphomas. In the past, recorded data indicated cancers were more prevalent in regions of high income like North America but in recent times, due to a number of factors including a change in diet corresponding with an increase in income, Africa has become a rising hot bed for different cancer types.

RISK FACTORS

  • Age:

    Cancer can affect persons of any age group but most individuals over 60 are at a higher risk than any other age group.

  • Habits and Lifestyle:

    Smoking of tobacco and chronic alcoholism.

  • Family history:

    Individuals with a family history of cancer.

  • Disease conditions:

    Certain disease conditions increase the likelihood of getting cancer. Ulcerative colitis and peptic ulcer disease are a few notable examples of conditions that may ultimately cause cancer.

  • Environmental factors:

    Exposure to harmful chemicals like benzene, particles like asbestos and ionizing radiation can result in genetic damage and cancer.

GENERAL SIGNS AND SYMPTOMS

The initial phase of cancer is asymptotic (without any noticeable symptoms), while later presentations depend on the type and site of the cancer. The general warning symptoms are:

  • Unexplained weight loss.
  • Fever and night sweats.
  • Fatigue.
  • Changes to skin color and texture
  • Mass growth appearance.
  • Ulceration.

COMPLICATIONS

The complications of cancer are usually a result of the abnormal cells’ invasive action to surrounding structures or the effects of cancer treatment on the patient.

  •  Chronic pain.
  • Difficulty in breathing.
  • Coughing up of blood.
  • Nausea.
  • Diarrhea and/or constipation.
  • Cardiac problems such as a myocardial infarction (heart attack).
  • Brain problems including headaches, cerebral infarction (brain cell death), stroke or cerebral herniation (shifting and squeezing of parts of the brain across structures in the skull).
  • Increased infections by microorganisms due to the anti-cancer drugs (chemotherapy) decreasing the action of the bone marrow; which is responsible for production of immune cells and mediators that fight infections. This side effect of chemotherapy is known as the suppressive effect on bone marrow.

 

DIAGNOSIS

  • Clinical manifestations of the patient and physical examinations.
  •  Tissue from a specific part of the body is taken for medical analysis and examination to find evidence of cancer and its type. This procedure is known as a biopsy
  • Imaging techniques are used to visualize internal structures of the body and to find physical evidence of cancers like masses. Computed Tomography (CT), Magnetic Resonance Imaging (MRI) and X -rays are examples of diagnostic imaging modalities used.

PROGNOSIS

The outcome of a cancer, whether good (compete recovery) or bad (death), depends on the type of cancer and stage at which it is diagnosed. Most patients have at least, a 5-year survival rate after the initial diagnosis. This is an average compared to the rest of the general population.

Regional estimates also differ, with higher mortality linked to developing areas like Africa and Asia. Advancements in the medical field have increased the survival rate of patients when an early diagnosis is made. Metastasis of cancer is almost, always associated with a bad prognosis because of the involvement of other organ systems, making the cancer relatively more difficult to treat.

MANAGEMENT

The treatment of cancer is usually complex, as decisions have to be taking by the physician based on the patient’s considerations, socioeconomic status and age. As a result, treatment of cancer isn’t always aimed at total recovery but sometimes at relieving the patient of the symptoms, and side effects of the cancer and its treatment. This focus on comfort, symptom management and patient support is known as Palliative Care.

For most patients however, the choice of treatment is to achieve a complete recovery, known as Curative Management; and Adjuvant Management to prevent reoccurrence of cancer.

METHODS OF MANAGEMENT

  • Surgery:

    This is the primary mode of treatment and involves removal of the cancer cells by surgical procedures, depending on the extent of spread.

  • Radiation:

    In radiation therapy, ionizing radiation is used to kill cancer cells by severely damaging the DNA of the cells. The source of the radiation may be internal (brachytherapy) or external and is usually limited to the cancer site to reduce collateral damage to neighboring normal cells.

  • Chemotherapy:

    The use of drugs to kill cancer cells.

  • Immunotherapy:

    The use of drugs to boost the immune system, enhancing its ability to detect and kill cancer cells.

  • Hormonal blocking or hormonal receptor blocking drugs:

    These drugs inhibit the activity of hormones that increase the growth of cancer cells.

PREVENTIVE MEASURES

Although it is generally impossible to determine the specific cause of cancers, there are various actions that can be taken to reduce the risks of getting cancers.

  • Avoiding smoking.
  • Protection from excessive radiation exposure.
  • Protection from carcinogenic substances like benzene.
  • Avoiding chronic alcohol use.
  • Starting a healthy diet.