Definitions:

Cancer: An uncontrolled prolifferation of mutated cells

Tumour:  Abnormal growth tissue that is capable of metastisisng to oter tissues

Neoplasm/ia: A new and abnormal growth of tissue, not always a mass. Can be used interchangably with tumour

Benign: Non-cancerous tissue which is usually encapulated meanng it isnot capable of spreading

Malignant: Rapid growing cells which are not encapsulated meaning that mutated cells can spread to vessels and nearby structures

Carcinoma: A cancer that develops in epithelial cells, of the skin and linings of body tissues. This affects squamus and basal cells.

Lymphoma: Cancer in lympatic tissues. Lymphoma originates in developing B-lymphocytes and T-lymphocytes, which have undergone a malignant (cancerous) change. These tumours cause swelling in the lymph nodes and other parts of the body. Over time, malignant lymphocytes (called lymphoma cells) crowd out normal lymphocytes and eventually the immune system becomes weakened and can no longer function properly.

Sarcoma: Sarcomas grow in connective tissue, cells that connect or support other kinds of tissue in your body. These tumors are most common in the bones, muscles, tendons, cartilage, nerves, fat, and blood vessels of your arms and legs, but they can happen anywhere.

Luekaemia: a malignant progressive disease in which the bone marrow and other blood-forming organs produce increased numbers of immature or abnormal leucocytes. These suppress the production of normal blood cells, leading to anaemia and other symptoms.

Dysplasia: the enlargement of an organ or tissue by the proliferation of cells of an abnormal type, as  an early stage in the development of cancer.

Invasive dysplasia: mutated cells spreading to surrounding tissues

Apoptosis: the death of cells which occurs as a normal and controlled part of an organism’s growth or development.

Metastasis:  The spread of cancer cells from the place where they first formed to another part of the body. In metastasis, cancer cells break away from the original (primary) tumor, travel through the blood or lymph system, and form a new tumor in other organs or tissues of the body.Common sites for metastasis are bones, liver, lungs and the brain.

Angiogenesis:  Blood vessel formation. Tumor angiogenesis is the growth of new blood vessels that tumors need to grow. This process is caused by the release of chemicals by the tumor and by host cells near the tumor.

Tumour suppressor genes: Tumor suppressor genes are normal genes that slow down cell division, repair DNA mistakes, or tell cells when to die (a process known as apoptosis or programmed cell death). When tumor suppressor genes don’t work properly, cells can grow out of control, which can lead to cancer 

Inactivation of the p53 tumor suppressor is a frequent event in tumorigenesis. In most cases, the p53 gene is mutated, giving rise to a stable mutant protein whose accumulation is regarded as a hallmark of cancer cells. Mutant p53 proteins not only lose their tumor suppressive activities but often gain additional oncogenic functions that endow cells with growth and survival advantages. This video discusses tumour suppressor genes.

Proto oncogenes: These genes code for proteins that help regulate cell growth. These important genes are called proto-oncogenes. A change in the DNA sequence of the proto-oncogene gives rise to an oncogene, which produces a different protein and interferes with normal cell regulation.

Oncogene: a gene which in certain circumstances can transform a cell into a tumour cell. Check this video out which explains oncogenes.

Carcinogenesis: Carcinogenesis or oncogenesis or tumorigenesis is the formation of a cancer, whereby normal cells are transformed into cancer cells. The process is characterized by changes at the cellular, genetic, and epigenetic levels and abnormal cell division, in some cancers forming a malignant mass.

Here’s a video exploring  cancer:

Development of cancer

The fundamental abnormality resulting in the development of cancer is the continual unregulated proliferation of cancer cells. Rather than responding appropriately to the signals that control normal cell behavior, cancer cells grow and divide in an uncontrolled manner, invading normal tissues and organs and eventually spreading throughout the body. The generalized loss of growth control exhibited by cancer cells is the net result of accumulated abnormalities in multiple cell regulatory systems and is reflected in several aspects of cell behavior that distinguish cancer cells from their normal counterparts.

Cell growth cycle

cellcycle

Retrieved from http://sphweb.bumc.bu.edu/otlt/mph-modules/ph/aging/CellCycle.png

There are three phases in the development of cancer: initiation, promotion and progression.

Initiation: 

This occurs when there is a mutation the the cells DNA structure from exposure to a carcinogen, radiation, or virus, a genetic defect or error during DNA replication. This is a irreversible process but many cells undergo apoptosis when the mutation is detected. Although most carcinogens are safetly removed from the body, failure in protective mechanisms can alter cellular DNA.

Chemical carcinogens:

  • alkylating agents
  • immuunosuppressive therapy
  • Asbestos
  • Arsenic and inorganic arsenic compounds.

Radiation:

  • UV radiation
  • Medical xrays, MRI

Viral carcinogens:

  • AIDs
  • Hepatitis B
  • human papillomavirus

Promotion

This stage is charecterized by the proliferation of of the altered cell. In the presence of promoting agents, cells become cancerous. Promoting agents are:

  • smoking
  • diet
  • alcohol
  • obesity

Changing lifestyle behaviours can decrease the likelyhood of mutated cells developing into cancerous cells.

Progression

This is the final phase of cancer. It is characterised by the increased growth of the tumour, invasive growth, and metastasis. During this stage, the tumour develops a vascular network (angiogensis) to ensure the deliver of adequate nutritions to the proliferating cells.

Cancer staging

Stage What it means
Stage 0 Abnormal cells are present but have not spread to nearby tissue. Also called carcinoma in situ, or CIS. CIS is not cancer, but it may become cancer.
Stage I, Stage II, and Stage III Cancer is present. The higher the number, the larger the cancer tumor and the more it has spread into nearby tissues.
Stage IV The cancer has spread to distant parts of the body.

Retrieved from https://www.cancer.gov/about-cancer/diagnosis-staging/staging

Cancer continuum

cancer-continuum

Retrieved from http://cebp.aacrjournals.org/content/12/1/4

Clinical manifestation of cancer

Infection: Cancer can increase the risk of infection. Some types of cancer can damage the immune and blood systems or change the way they work Infections that develop in people who have cancer or who are getting cancer treatment can be more serious than those in people who are otherwise healthy. They can also be harder to treat. Chemo and radiation damage the bone marrow and suppress its function resulting in decreased WBC, thrombocytes, and neutophils. Prophalyaxis antibiotics are used when cancer patients develop an increased temperature as they are more susceptible to life threatening complications. Additionally filgrastim can be administered to provide protection from infection.

Anaemia: Cancer or cancer treatment can affect the development of RBC due to damage of malignancy of the bone marrow. Anemia is common for people with cancer, especially for those receiving chemotherapy. Most people with anemia feel tired or weak. This fatigue can make difficult for patients to cope with the physical and emotional demands of treatment. Signs and sypmtoms:

  • Fatigue
  • Muscle weakness
  • Arythmyia
  • Pale skin
  • Difficulty staying warm

Treatment for anaemia may consist of packed red blood cells, vitamin or mineral supplements, or erythropoiesis-stimulating agents.

Thrombocytopenia: This is a decreased in the amount of platelets less than 150,000 due to damage to the functioning of bone marrow. Low platelets can cause haemorrhage in cancer pateints. Signs may include:

  • Bruising easy
  • Excessive bleeding
  • Blood in urine or stools

Transfusions of either PRBC or platelets can be used to treat low platelets.

Pain: Pain occurs in 80-90% of patients in late stage cancer. It can be associated with pressure, obstruction or stretching of the tissues. Pan can also be affected by fear, anxiety, sleep loss and fatigue. For longstanding chronic pain associated with cancer, vital signs are not a reliable indicator of the severity. It is important to gather subjective information as inadequate pain assessment is the biggest barrier to patients receiving adequate relief.

  • Administer opioid analgesics (Monitor for constipation)
  • Treat inflammation with corticosteroids (Immunosupressant, must be carefully monitored)
  • Encourage the use of a pain diary
  • Distraction, breathing exercises, guided imagery

Anorexia/Cachexia: weakness and wasting of the body due to severe chronic illness. This will becoe more pronounce towards the end of life. A decline in food intake relative to energy expenditure (which may be increased, normal, or decreased) is the fundamental physiologic derangement leading to cancer-associated weight loss. In addition, abnormalities of carbohydrate, protein, and fat metabolism lead to continued mobilization and ineffective repletion of host tissue, despite adequate nutritional support.

  • Offer small, frequent meals
  • Appetite stimulants
  • High energy/high protein supplements

 

Treatment options

Chemotherapy

Alkylating agents/nitrsoureas: This causes the double helix to become tied together, which effectively blocks the unwinding of the DNA strands. This inhibits the process of DNA replication within cells. This stops cell proliferation in the S phase of the cellular growth cycle.

Platinum/antitumour AB/antimetabolites: Metabolites are the building blocks of DNA. During the S phase of cellular growth, gemcitabine masquerades as either purine or pyrimidine, which prevents these metabolites becoming incorporated during DNA synthesis. This prevents the DNA of cancerous cells replicating, inhibiting cell proliferation, and causing to cell death

Miotic inhibitors/antimicrotubules: A mitotic inhibitor is a drug that inhibits mitosis, or cell division. These drugs disrupt microtubules, which are structures that pull the cell apart when it divides. One of the important functions of microtubules is to move and separate chromosomes and other components of the cell for cell division

Radiation: This is commonly used alongside chemotherapy to treat cancer. The type and location of the cancer will influence how often radiotherapy is needed. The patient may only need a one of dose or for longer courses, radiation sessions may be given 4-5 days a week. External beam therapy is the most common type of radiation therapy. It is a high energy radiation that is focused from outside of the body to target cancer cells. The radiation beam is directed to the area of cancerous cell growth. However, radiation is non-selective and healthy cells can also be damaged in the radiation process. The radiation damages the DNA within the cell, causing cell death. Additionally, free radicals within the cell as a result of the radiation damage the DNA. Cells with damaged DNA are unable to undergo the mitosis process, decreasing proliferation and resulting in cell death

 

 

 

References

Grivennikov, S. I., Greten, F. R., & Karin, M. (2010). Immunity, inflammation, and cancer. Cell, 140(6), 883–899. doi: 10.1016/j.cell.2010.01.025

Stephens, M. (2015). Cancer. In J. Craft & C. Gordon (Eds.), Understanding pathophysiology (2nd ed., pp. 1061–1103). Sydney, Australia: Mosby Elsevier.

Yates, P. (2008). Cancer. In D. Brown & H. Edwards (Eds.), Lewis’s medical-surgical nursing: Assessment and management of clinical problems (2nd ed., pp. 302–344). Sydney, Australia: Mosby Elsevier.

 

 

 

Advertisements