breast cancer

Examples of breast cancer in the following topics:

• Breast Cancer

  • Breast cancer is one that grows in the breast tissue of humans and often originates in the milk ducts.
  • Breast cancer (malignant breast neoplasm) is a type of cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply them.
  • In 2008, breast cancer caused 458,503 deaths worldwide, and 13.7% of all cancer deaths in women.
  • The earliest breast cancers are detected by a mammogram.
  • Normal breast tissue left versus cancerous breast tissue right, as shown by mammography images.

• Cell Signaling and Cell Growth

  • Cancer biologists study the molecular origins of cancer with the goal of developing new prevention methods and treatment strategies that will inhibit the growth of tumors without harming the normal cells of the body.
  • Cancer biologists have been able to identify many other oncogenes that contribute to the development of cancer.
  • For example, HER2 is a cell-surface receptor that is present in excessive amounts in 20 percent of human breast cancers.
  • Cancer biologists realized that gene duplication led to HER2 overexpression in 25 percent of breast cancer patients and developed a drug called Herceptin (trastuzumab), a monoclonal antibody that targets HER2 for removal by the immune system.
  • Its use, in combination with chemotherapy, has helped to increase the overall survival rate of patients with metastatic breast cancer.

• Cancer and Post-Transcriptional Control

  • Changes in the post-transcriptional control of a gene can result in cancer.
  • It appears that the subset of miRNAs expressed in breast cancer cells is quite different from the subset expressed in lung cancer cells or even from normal breast cells.
  • This suggests that alterations in miRNA activity can contribute to the growth of breast cancer cells.
  • It would, therefore, be conceivable that new drugs that turn off miRNA expression in cancer could be an effective method to treat cancer.
  • Specific types of miRNAs are only found in cancer cells.

• Cancer and Transcriptional Control

  • Alterations in cells that give rise to cancer can affect the transcriptional control of gene expression.
  • This could also lead to the increased transcription and aberrant gene expression that is seen in cancer cells.
  • In breast cancer, for example, many proteins are overexpressed.
  • One such example is the overexpression of the epidermal growth factor receptor (EGFR) in a subset of breast cancers.
  • New drugs that prevent the activation of EGFR have been developed and are used to treat these cancers.

• Effects of Smoking

  • Figure 1 shows the correlation between smoking and lung cancer.
  • Among the diseases that can be caused by smoking are vascular stenosis, lung cancer, heart attacks, and chronic obstructive pulmonary disease.
  • Tobacco use leads most commonly to diseases affecting the heart and lungs, with smoking being a major risk factor for heart attacks, strokes, chronic obstructive pulmonary disease (COPD) (including emphysema and chronic bronchitis), and cancer (particularly lung cancer, cancers of the larynx and mouth, and pancreatic cancer).
  • The primary risks of tobacco usage include many forms of cancer, particularly lung cancer, kidney cancer, cancer of the larynx and head and neck, breast cancer, bladder cancer, cancer of the esophagus, cancer of the pancreas, and stomach cancer.
  • There is some evidence suggesting a small increased risk of myeloid leukemia, squamous cell sinonasal cancer, liver cancer, colorectal cancer, cancers of the gallbladder, the adrenal gland, the small intestine, and various childhood cancers.

• Cancer and Translational Control

  • There are many examples of translational or post-translational modifications of proteins that arise in cancer.
  • An example of how the expression of an alternative form of a protein can have dramatically different outcomes is seen in colon cancer cells.
  • However, in colon cancer cells, expression of the long form results in increased cell growth instead of cell death.
  • Clearly, the expression of the wrong protein dramatically alters cell function and contributes to the development of cancer.
  • One such example is the use of anti-EGF receptor medications to treat the subset of breast cancer tumors that have very high levels of the EGF protein.

• Metastasis Through Lymphatic Vessels

  • Cancer occurs after a single cell in a tissue is progressively genetically damaged to produce a cancer stem cell possessing a malignant phenotype.
  • These cancer stem cells are able to undergo uncontrolled abnormal cell division, which increases the total number of cancer cells at that location.
  • Micrograph showing a lymph node invaded by ductal breast carcinoma and with extranodal extension of tumour.
  • Surrounding the lymphocytes and extending into the surrounding fat (top of image) is ductal breast carcinoma.
  • The cancer (forming glands) is seen at the centre-top.

• Overview of Cancer

  • A major hallmark of cancers is metastasis, the ability of the cancer to spread between tissues and organs within the body.
  • Due to the wide variety of cancerous diseases, six hallmarks are used to group and define cancers:
  • 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.
  • For example, familial mutations of the BRCA1 and BRCA2 genes are associated with an increased risk of developing breast cancer.
  • For certain types of cancer, such as early head and neck cancer, it may be used alone.

• Ovarian Cancer

  • Ovarian cancer is a cancerous growth arising from the ovary.
  • Since the ovaries and tubes are closely related to each other, it is thought that these fallopian cancer cells can mimic ovarian cancer.
  • These cancers are grouped into the category of gynecologic cancer.
  • In most cases, the exact cause of ovarian cancer remains unknown.
  • This can halt or slow breast and ovarian cancers that need these hormones to grow.

• Testicular Cancer

  • Testicular cancer is cancer that develops in the testicles, a part of the male reproductive system.
  • Over his lifetime, a man's risk of testicular cancer is roughly 1 in 250 (0.4%).
  • Testicular cancer has one of the highest cure rates of all cancers: in excess of 90%; essentially 100% if it has not spread (metastasized).
  • Although testicular cancer can be derived from any cell type found in the testicles, more than 95% of testicular cancers are germ cell tumors .
  • However, the American Cancer Society suggests that some men should examine their testicles monthly, especially if they have a family history of cancer.