Cancer

There is also a constellation named Cancer: see Cancer (constellation).

Cancer has become an important problem with the rise in life expectancy, as the mutations become more likely the longer a person lives. Though great progress in treatment has been made, many cancers reach advanced stages remain incurable and ultimately fatal. Thankfully for patients with incurable cancer, the last 20 years have seen the widespread availability of palliative care.

Cancer is treated by an oncologist, a doctor specialized in the treatment of malignant disease.

Table of contents

1 Prevention and early detection 2 Forms of cancer 3 Treatment 4 Biology of malignant tumors 4.1 Carcinogenesis 4.2 Metastasis 5 Cancer research agencies and funding bodies 6 See also 7 External links

Prevention and early detection

Proven methods of decreasing the risk of cancer include smoking cessation – stop smoking!! and avoiding other known carcinogens such as sunlight, genital warts.

Accepted early detection strategies include:

• breast self-examination and regular screening mammograms
• Pap smears
• testicular self-examination – for men from the age of 15 years
• prostate examination +/- serum acid phosphatase levels
• annual prostate specific antigen blood test
• fecal occult blood test or stool guaiac testing and colonoscopy (above age 50, lower if risk factors present)

Both white and Green tea have been shown to help in preventing cancer in rats, but the significance of this in humans is unknown.

Forms of cancer

• adenoma
• carcinomas from epithelial cells
  • squamous cell carcinoma
• Leukemia
• Lymphoma
• Melanoma
• Sarcoma from connective tissue, bone or muscle
• Teratoma

• Bladder carcinoma
• Blood and bone marrow) Hematological malignancies
  • Leukemia
  • Lymphoma
    • Hodgkin's disease
    • Non-Hodgkin's lymphoma
  • Multiple myeloma
• Brain tumor
• Breast cancer
• Cervical cancer
• Colorectal cancer (includes colon, rectum, anus, and appendix)
• Esophageal cancer
• Endometrial cancer (uterus)
• Hepatocellular carcinoma (liver)
• Gastrointestinal stromal tumor (GIST)
• Laryngeal cancer
• Lung cancer
• Mesothelioma
• Oral cancer
• Osteosarcoma (bone)
• Ovarian cancer
• Pancreatic cancer
• Prostate cancer
• Renal cell carcinoma (kidney)
• Rhabdomyosarcoma (muscle)
• Skin cancer, including benign Moles and dysplastic nevi
• Stomach cancer
• Testicular cancer
• Thyroid cancer

• Surgery
• Chemotherapy
• Radiation therapy
• Immunotherapy
• Cytoluminescent Therapy (CLT)
• Experimental cancer treatments

Carcinogenesis

Cancer is, ultimately, a disease of genes. Typically, a series of several mutations is required before a cell becomes a cancer cell. The process involves both oncogenes and tumor suppressor genes. Oncogenes promote cancer when "switched on" by a mutation, whereas tumor suppressor genes prevent cancer unless "switched off" by a mutation. Chromosomal translocation, such as the Philadelphia chromosome, is special type of mutation and may involve oncogenes or tumor suppressor genes.

Mutations can have various causes:

• tobacco smoking
• radiation, including ultraviolet radiation from the sun
• chemicals called carcinogens
• viral or bacterial infection, such as the Human papillomavirus viruses in cervical cancer and Helicobacter pylori bacteria
• DNA damage by free radicals
• inherited predisposition, such as the BRCA1 gene in breast cancer
• chronic inflammation from any cause

It is impossible to tell the initial cause for most of the cancers.

However, with molecular biology, it is now possible to characterize the mutations within a tumor, and to a certain extent predict its behavior. For example, about half of the tumors are deficient in the tumor suppressor gene p53, also known as "the guardian of the genome". This mutation is associated with poor prognosis, since those tumor cells are less likely to go into apoptosis (programmed cell death) when damaged by therapy. There are more mutations that make a tumor more malignant. Telomerase mutations enable a tumor cell to divide indefinitely. Other mutations enable the tumor to grow new blood vessels to feed it, or to detach from the surrounding tissue, spreading to other parts of the body.

Malignant tumors cells, such as in carcinoma, sarcoma, lymphoma or leukemia, have distinct properties:

• evading apoptosis
• unlimited growth potential (immortalitization)
• self-sufficiency of growth factors
• insensitivity to anti-growth factors
• increased cell division rate
• altered ability to differentiate
• no ability for contact inhibition
• ability to invade neighbouring tissuess
• ability to build metastases at distant sites
• ability to promote blood vessel growth (angiogenesis)

In cellular model systems, cells are exposed to carcinogenic influences (chemicals, radiation). In these systems, the first signs of a cell developing into a tumor cell are:

1. Immortality. The usual number of cell divisions for a mammalian cell is 50-60 (cell senescence), then it ceases to divide. Tumor cells keep dividing forever.
2. Altered morphology.
3. Building of cellular clusters (foci).
4. Loss of contact inhibition.
5. Low or no need for growth factors.

Metastasis

Cancer research agencies and funding bodies

• American Cancer Society
• BC Cancer Agency
• Cancer Research UK
• Canadian Cancer Society
• International Agency for Research on Cancer
• National Cancer Institute (US)
• Yorkshire Cancer Research

External links

• Cancer News from Genome News Network (GNN)
• National Cancer Institute
• Cancer from the Open Directory Project
• Cancer Medicine, online textbook.

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