A Review Report on cancer treatment

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About Authors:
Jaideep Sharma
Guru jambheshwar university of science & technology    
Hisar,
Haryana

Cancer, known medically as a malignant neoplasm is a term for a large group of different disease, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumours, and invade nearby parts of the body. The cancer may also spread to more distant parts of the body through the lymphatic system or bloodstream. Not all tumours are cancerous. Benign tumours do not grow uncontrollably, do not invade neighbouring tissues, and do not spread throughout the body.
Healthy cells control their own growth and will destroy themselves if they become unhealthy. Cell division is a complex process that is normally tightly regulated. Cancer occurs when problems in the genes of a cell prevent these controls from functioning properly. These problems may come from damage to the gene or may be inherited, and can be caused by various sources inside or outside of the cell. Faults in two types of genes are especially important: ontogenesis, which drive the growth of cancer cells, and tumour suppressor genes, which prevent cancer from developing.

Reference Id: PHARMATUTOR-ART-1201

What causes cancer?
Many things are known to increase the risk of cancer, including tobacco use, infection, radiation, lack of physical activity, poor diet and obesity, and environmental pollutants.[1] These can directly damage genes or combine with existing genetic faults within cells to cause the disease.[2] A small percentage of cancers, approximately five to ten percent, are entirely hereditary.
Cancers are primarily an environmental disease with 90-95% of cases attributed to environmental factors and 5-10% due to genetics.[1]Environmental, as used by cancer researchers, means any cause that is not genetic, not merely pollution. Common environmental factors that contribute to cancer death include tobacco (25-30%), diet and obesity (30-35%), infections (15-20%), radiation (both ionizing and non-ionizing, up to 10%), stress, lack of physical activity, and environmental pollutants.[2]

Path physiology of cancer:[5]
Cancer is fundamentally a disease of failure of regulation of tissue growth. In order for a normal cell to transform into a cancer cell, the genes which regulate cell growth and differentiation must be altered.
The affected genes are divided into two broad categories  .Oncogenes are genes which promote cell growth and reproduction. Tumours suppression genes are genes which inhibit cell division and survival. Malignant transformation can occur through the formation of novel oncogenes, the inappropriate over-expression of normal oncogenes, or by the under-expression or disabling of tumour suppressor genes. Typically, changes in many genes are required to transform a normal cell into a cancer cell.
Genetic changes can occur at different levels and by different mechanisms. The gain or loss of an entire chromosome can occur through errors in mitosis More common are mutations, which are changes in the nucleotide sequence of genomic DNA.
Large-scale mutations involve the deletion or gain of a portion of a chromosome. Genomic application occurs when a cell gains many copies (often 20 or more) of a small chromosomal locus, usually containing one or more oncogenes and adjacent genetic material. Translocation occurs when two separate chromosomal regions become abnormally fused, often at a characteristic location. A well-known example of this is the Philadelphia chromosome, or translocation of chromosomes 9 and 22, which occurs in chronic myeloid leukaemia, and results in production of theBCR abl fusion protein , an oncogenic tyrosine kinase .
Small-scale mutations include point mutations, deletions, and insertions, which may occur in the promoter region of a gene and affect its expression, or may occur in the gene's coding genes and alter the function or stability of its protein product. Disruption of a single gene may also result from integration of genomic material from a DNA virus or retrovirus, and resulting in the expression of viral oncogenes in the affected cell and its descendants.
Replication of the enormous amount of data contained within the DNA of living cells will probabilistically result in some errors (mutations). Complex error correction and prevention is built into the process, and safeguards the cell against cancer. If significant error occurs, the damaged cell can "self-destruct" through programmed cell death, termed apoptosis. If the error control processes fail, then the mutations will survive and be passed along to daughter cells.

Some environments make errors more likely to arise and propagate. Such environments can include the presence of disruptive substances called carcinogens, repeated physical injury, heat, ionising radiation, or hypoxia .

The errors which cause cancer are self-amplifying and compounding, for example:
· A mutation in the error-correcting machinery of a cell might cause that cell and its children to accumulate errors more rapidly.
· A further mutation in an oncogene might cause the cell to reproduce more rapidly and more frequently than its normal counterparts.
· A further mutation may cause loss of a tumour suppressor gene, disrupting the apoptosis signalling pathway and resulting in the cell becoming immortal.
· A further mutation in signalling machinery of the cell might send error-causing signals to nearby cells.

 Figure 1. Acquired Capabilities of Cancer

Types of cancer
Cancers are classified by the type of cell that the tumour resembles and is therefore presumed to be the origin of the tumour. These types include:

  • Carcinoma: Cancers derived from epithelial cells. This group includes many of the most common cancers, particularly in the aged, and include nearly all those developing in the breast, prostate, lung, pancreas, and colon.
  • Sarcoma: Cancers arising from connective tissue (i.e. bone, cartilage, fat, nerve), each of which develop from cells originating in mesenchymal cells outside the bone marrow.
  • Lymphoma and leukaemia: These two classes of cancer arise from hematopoietic (blood-forming) cells that leave the marrow and tend to mature in the lymph nodes and blood, respectively.
  • Germ cell tumour: Cancers derived from pluripotent cells, most often presenting in the testicle or the ovary (seminoma and dysgerminoma, respectively.
  • Blastoma: Cancers derived from immature "precursor" cells or embryonic tissue. These are also most common in children.

EPIDEMIOLOGY
In 2008 approximately 12.7 million cancers were diagnosed (excluding non-melanoma skin cancers and other non-invasive cancers) and 7.6 million people died of cancer worldwide.[3] Cancers as a group account for approximately 13% of all deaths each year with the most common being: lung cancer (1.3 million deaths), stomach cancer (803,000 deaths), colorectal cancer (639,000 deaths), liver cancer (610,000 deaths), and breast cancer (519,000 deaths). this makes invasive cancer the leading cause of death in the developed world and the second leading cause of death in the developing world.[3] Over half of cases occur in the developing world.[3]

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