What is cancer?

Cancer affects people of all ages, regardless of gender and ethnicity, with the risk for most types increasing with age. It is responsible for approximately 7.6 million human deaths in 2007. It is a class of diseases in which a cell or a group of cells display uncontrollable growth, invasion to adjacent tissues and sometimes metastasize (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumours, which are self-limiting, and do not invade or metastasize. Most of them form a tumour but some, like leukaemia, do not.

 

 

 

Classification of cancer

Cancers are classified by the type of cells that resemble the tumour and the tissues presumed to be the origin of the tumour. The general categories of include:
• Carcinomas: These malignant tumours originate from epithelial cells. This group represents the most common of cancers, including breast, prostate, lungs and colon cancer.
• Sarcomas: These malignant tumours originate from connective tissues and mesenchymal cells (loose connective tissues located in the embryo).
• Leukaemia and lymphomas: These malignancies originate from hematopoietic (blood-forming) cells
• Germ cell tumours: These tumour cells originate from totipotent cells. Totipotent cells have the ability to divide and produce all the differentiated cells in an organism. These cells are found in the testicles and ovaries in adults and on the body midline, particularly around the tip of the tailbone in foetuses, babies and young children

The picture on the left shows a person with basal call carcinoma on the face while the one on the right shows oral cancer on the tongue


The picture on the left shows the cancer of the colon while the picture on the right shows sqamous cell carcinoma of the lungs.

Signs and symptoms of cancer

The signs and symptoms can be roughly divided into:
• Local symptoms: unusual humps or swellings, bleeding, pain, or ulceration. Compression of tissues around the area may symptoms such as jaundice.

• Symptoms of metastasis: enlarged lymph nodes, cough and hemoptysis (coughing up of blood or blood stained sputum), hepatomegaly (enlarged liver), bone pain, fractures of affected bones and neurological symptoms. Although advanced cancer may cause pain, it is often not the first symptom.

Causes of cancer

Cancers are primarily an environmental disease with 90 to 95 percent of cases due to lifestyle and environmental factors. Only 5 to 10 percent is due to genetics. The common environmental factors that lead to the onset of the disease include diet and obesity, tobacco, infections, radiations, stress, physical activity and environmental pollutants. Diet and obesity is the major contributing cause accountable to 30 to 35 percent of cases, while tobacco accounts for 25 to 30 percent. Its pathogenesis is traceable back to DNA mutations that impact cell growth and metastasis. Substances that cause DNA mutations are called mutagens while substances that cause cancers are called carcinogens. Many mutagens are carcinogens but not all carcinogens are mutagens, alcohol being an example. Research has shown the link between the usage of tobacco and cancer in the lungs, larynx, head, neck, stomach, bladder, kidneys, oesophagus and pancreas.  
TOBACCO SMOKE CONTAINS MORE THAN FIFTY KNOWN CARCINOGENS, including nitrosamines and polycyclic aromatic hydrocarbons. Tobacco is responsible for about one in three deaths of all lung cancers in the developed world.

Sources of ionising radiation, such as radon gas, can cause cancer. Prolonged exposure to ultraviolet light form the sun can lead to melanoma and other skin malignancies.

Some cancers are caused by infections, with viruses responsible for up to 20 percent of human cancers. These include human papilomavirus (cervical cancer), human polymavirus (mesothelioma, brain tumours), Epstein-Barr virus (B-cell lymphoproliferative diseases and nasopharyngeal carcinoma), Karposi’s sarcoma herpesvirus (Karposi’s sarcoma and primary effusion lymphomas), hepatitis B and hepatitis C viruses (hepatocellular carcinoma), Human T-cell leukaemia virus-1 and Helicobacter pylori (gastric carcinoma).

Prevention of Cancer

Cancer prevention is defined as the active measures taken to decrease the incidence of the disease. More than 30 percent of cancers are preventable by avoiding risk factors such as alcohol, tobacco, obesity, inadequate consumption of fruits and vegetables, physical inactivity and pollution.




Fruits and vegetables do contain ingredients that prevent cancer and promote general health. But is it possible to eat all the items mentioned in the video? Furthermore the shelf life of fresh fruits and vegetable may be short and certain vitamins are heat-labile, that is they will perish when they are cooked. At the end of the video, it states that the world’s lowest cancer rates are in the regions in Japan where green tea is harvested. Green tea has a potent cancer-fighting antioxidant called catechins.

We are often so tied up with our busy lifestyle that we may not have time to eat healthily. In my humble opinion, people should take supplements on top of their daily intake of fruits and vegetables to provide their bodies with a more wholesome coverage of vitamins, minerals and antioxidants.

It would seem that diet, obesity and lifestyle play an important role not only in cancer but also in high blood pressure, diabetes and hypercholesterolemia. Take simple steps in reducing the risks and preventing the onset of such diseases.