Cancer Therapy and Pathophysiology

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Cancer is defined as a medical disorder characterized by uncontrolled growth of cells beyond normal limits, followed by invasion from adjacent tissues. It is spread to other body parts by lymph or blood through metastasis. The division of cancerous cells progresses from initiation and promotion till formation of malignant tumors. The diagrammatic representation of formation of cancer cells in the body is shown below:  

Source: Adapted from .


Cell growth is systematic process which has balance between growth of new cells and death of old ones. However, cancerous cells creates imbalance of the normal mechanism and causes excessive growth. Carcinogenesis causes derangement of division of cells due to damage of DNA. Proto-oncogenes, responsible for cell growth are impaired in carcinogenesis due to mutations. Proto-oncogenes become over expressed to cause excessive uncontrolled cell growth. Additionally, Tumor suppressor genes which become active during dell repair, also gets deactivated during mutagenesis caused by cancer and the ability to repair DNA gets witched off. Mutations to proto-oncogenes and tumor suppressor genes are the main patho-physiological causes of cancer and multiple tumors.

Substances which initiate mutations and DNA damage in the human body are termed as mutagens or carcinogens. These mutagens are specific and differ for different types of cancer. For example, smoking is responsible for lung cancer and continuous exposure to UV rays cause skin cancer. Some cancers are also caused by infections but this occurs very rarely in human beings as it is more common in birds. Causes of cancer are habitual, environmental and genetic. Several molecular biological techniques can be used to detect and diagnose cancer.

Source: Adapted from National cancer Institute website.


There are many means of treating and managing cancer. These include chemotherapy, radiation, immunotherapy, surgery and use of monoclonal antibodies. Treatment condition and option depends on the type, stage of cancer a patient is suffering from and the location of cancer in human body.

  • Chemotherapy and medications: Use of medication and chemicals for cancer therapy is recommended for improvement of patient condition successfully by many clinical trials. Some of the medications used include, tamoxifen (Selective estrogen receptor modulator) which reduces the risk of breast cancer in women. Raloxifene is another SERM used in the same category (Vogel et al., 2006). Finasteride (5-alpha reductase inhibitor) is used to reduce the risk of prostrate cancer and low grade tumors (Thompson et al., 2003). Rofecoxib and celecoxib are COX-2 inhibitors which reduce the risk of polyps of colon (Baron et al., 2006).Vitamin and minerals supplement acts as adjuvant in cancer therapy and slightly increased vitamin and mineral doses may cause cancerous symptoms although not proved scientifically (Prescrire international).

  • Vaccines: Vaccines have been developed recently against the epitopes of cancer, to prevent the body against infection. Example of such vaccine is Gardasil and Cervarix (human papillomavirus vaccine), which reduces risk of liver cancer (Retrieved from cancer vaccine fact sheet).

  • Radiation:  Radiation or radiotherapy is used along with chemotherapy or hormone therapy. In this treatment, ionizing radiation is given as a part of treatment for cancer. It is given as a direct treatment in terminally ill patients or as an adjuvant in some types of malignant cancer. Radiotherapy differs from patient to patient and depends on the age of patient, nature of tumor and mode of advised treatment.


Use of Immunotherapy in treating cancer is widely researched now a days to improve patient’s condition and to reduce the side effects of radiotherapy and chemotherapy.

Regulatory T cells are mainly responsible for induction and maintenance of peripheral tolerance. This T-cell population type influences activity of other cell type and suppresses immune response (Shevach, 2004). Studies by North and his colleagues also revealed that CD4+ and CD25+ T cells from mice bearing tumour inhibited rejection, suggesting the presence of tumour suppressor T cells in them. This study formed a historical evidence for regulatory T cells in immunological therapy of tumours (North and Bursuker, 1984). Regulatory T cells are combination of CD4+CD25+FOXP3+ T cells (TReg cells).

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In the past, immunosuppression by T-cells has been reported as a major obstacle for immunotherapy. Reduction of T-cell trafficking, differential functioning and signalling is the basis of novel therapeutic strategies for cancer.

T-regulatory cells in human tumours: Investigations by Sakaguchi and Curiel suggest that failure of anti-tumour immunity is related to suppression of TAA reactive lymphocytes by mediation of T-regulatory cells. Investigations also revealed the presence of T-regulatory cells in peripheral blood stream in all types of cancer which could be the reason for reduced TAA specific T- cell immunity in cancers rather than the suppressive activity ...

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