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Cancer, a word that elicits dread in nearly everyone, continues to puzzle scientists. Despite attempts made by science to decipher this terrible disease, scientists still struggle to find an answer to questions such as, ‘why does cancer strike some and not others?’, 'Are its ‘seeds’ part of our genetic makeup?'

Different terms are used when discussing cancer. Neoplasm is an abnormal cell mass that develops when the controls of the cell cycle and cell division malfunction. However, all neoplasms are not cancerous. Benign neoplasms do not spread, and are always seen to be local affairs. They are usually surrounded by a capsule and grow slowly, seldom killing their hosts if they are removed before they affect vital organs. Malignant neoplasms, on the other hand, are non-encapsulated, grow more relentlessly and can even kill. They resemble immature cells and invade their surroundings rather than push them aside. Malignant cells are also capable of metastasis – ie, they tend to spread via blood to distant parts of the body and form new masses.

But what causes the transformation? In other words, what converts a normal cell to a cancerous one? It is well known that cancer-causing elements or carcinogens can be found in radiation, mechanical trauma, certain viral infections and many chemicals (tobacco tars, saccharine). All of these have one common factor - all of them cause mutations, which are changes in DNA that alter the expressions of certain genes. Usually carcinogens are eliminated by the immune system or certain enzymes. It must also be stated here that it takes much more than just one mutation to change a normal cell into a full-fledged cancer cell.

It was with the discovery of oncogenes (cancer causing genes) followed by proto-oncogenes that the role of genes started to gain prominence. Although proto-oncogenes code for proteins that are needed for normal cell division and growth, many of them have fragile areas that break when exposed to carcinogens, converting them to oncogenes. As a result, problems such as, ‘switching on’ of dormant genes that allow cells to become invasive, arise. Oncogenes have been discovered in only 15 to 20 per cent of human cancers. Therefore, it came as no surprise when the tumour suppressor genes were discovered recently – these, as their names suggest, suppress or prevent cancer. The tumour suppressor genes not only put the ‘brakes’ on cell division but they help with DNA repair and help to deactivate carcinogens, thereby enhancing the immune system’s ability to destroy cancer cells. It is when the tumour suppressor genes are damaged or changed in some way, that the oncogenes are free to ‘do their thing’. Whatever the precise genetic factor at work, the seeds of cancer do appear to be in our own genes. Cancer is indeed intimate!

Direction: These questions are based on the information given below:

Cancer, a word that elicits dread in nearly everyone, continues to puzzle scientists. Despite attempts made by science to decipher this terrible disease, scientists still struggle to find an answer to questions such as, ‘why does cancer strike some and not others?’, 'Are its ‘seeds’ part of our genetic makeup?'

Different terms are used when discussing cancer. Neoplasm is an abnormal cell mass that develops when the controls of the cell cycle and cell division malfunction. However, all neoplasms are not cancerous. Benign neoplasms do not spread, and are always seen to be local affairs. They are usually surrounded by a capsule and grow slowly, seldom killing their hosts if they are removed before they affect vital organs. Malignant neoplasms, on the other hand, are non-encapsulated, grow more relentlessly and can even kill. They resemble immature cells and invade their surroundings rather than push them aside. Malignant cells are also capable of metastasis – ie, they tend to spread via blood to distant parts of the body and form new masses.

But what causes the transformation? In other words, what converts a normal cell to a cancerous one? It is well known that cancer-causing elements or carcinogens can be found in radiation, mechanical trauma, certain viral infections and many chemicals (tobacco tars, saccharine). All of these have one common factor - all of them cause mutations, which are changes in DNA that alter the expressions of certain genes. Usually carcinogens are eliminated by the immune system or certain enzymes. It must also be stated here that it takes much more than just one mutation to change a normal cell into a full-fledged cancer cell.

It was with the discovery of oncogenes (cancer causing genes) followed by proto-oncogenes that the role of genes started to gain prominence. Although proto-oncogenes code for proteins that are needed for normal cell division and growth, many of them have fragile areas that break when exposed to carcinogens, converting them to oncogenes. As a result, problems such as, ‘switching on’ of dormant genes that allow cells to become invasive, arise. Oncogenes have been discovered in only 15 to 20 per cent of human cancers. Therefore, it came as no surprise when the tumour suppressor genes were discovered recently – these, as their names suggest, suppress or prevent cancer. The tumour suppressor genes not only put the ‘brakes’ on cell division but they help with DNA repair and help to deactivate carcinogens, thereby enhancing the immune system’s ability to destroy cancer cells. It is when the tumour suppressor genes are damaged or changed in some way, that the oncogenes are free to ‘do their thing’. Whatever the precise genetic factor at work, the seeds of cancer do appear to be in our own genes. Cancer is indeed intimate!