Question

1. Define and give a paragraph-length example of each of the following sources of cancers:

a) environment

b) mutation (chromosomal)

c) inheritance

Answer 1

Cancer is a complex group of disease with many possible causes. Cancer causes cells to divide uncontrollably . This results in tumors, damages the immune system and other impairments in body .

It is a disease that result when cellular, changes causes the uncontrolled growth and division of cells .

There are many causes of cancer are smoking , heavy alcohol consumption, excess body weight, poor nutrition etc.

There are many types of cancer such as leukemia, pancreatic,thyroid, liver, melanoma etc.

a) There are various cancer causing substances in the environment

There are various cancer causing exposures such as tobacco, smoking and the sun rays .Nextly,the air we breathe , the water we drink and the food we eat.

A number chemical substances are released in higher concentrations which is dangerous to our health , this cancer causing agents are called carcinogens .

Eg : People working in certain job such as painting , construction, pesticide and petroleum workers have increased risk of cancer.

b) Most cancers develop because of genetic mutations. The stability of the human genome requires the mutation in the germ line . limited number of mutations are required for adaptation of environmental changes . The genetic mutation includes inactivation of tumor suppressor genes and activation of oncogenes.  

The individuals with major inherited predisposition to cancer are born with inherited mutation in genes involved in caner causation, giving a pathway to start in cancer .

similarly the mutation would be expected to result in cancer progression among all individuals, however in those without the inherited cancer predisposition , the mutation would occur as a somatic mutation during the whole life time .

c) Some faulty genes that increase the risk of cancer can be passed from parent to children These are called as inherited cancer genes. This occurs usually when there is a mistake in the gene in an egg or in sperm cell. then the gene fault may be passed to children.

Eg :certain types of cancer occur in some families than in rest population such as Familial Adenomatous Polyposis is an good example of hereditary colon type cancer.

We inherit genes from both our parents . If a parent has a gene fault then each child will have 50 % chance of inheriting it. some may have faulty gene and have increased risk of developing cancer and some won't .

It doesn't mean that the inherited faulty gene will have cancer. but the risk of developing the cancer will be high .

Hence these cancers can be treatable  when detected earlier by using various treatments such as chemotherapy , targeted therapy , hormonal therapy etc .