Cyto: Cancer Genetics

• Cancer is a group of diseases that involve uncontrolled division of cells due to failure of the mechanism that usually controls the growth and proliferation of cells.
• Cancer arises from a single cell which has undergone mutation.
• Stem cell or Bone Marrow transplant may be beneficial in certain cases.
• Hormone therapy may be used in certain cases.
• Some forms of gene therapy, may also prove helpful.
• Chemotherapy involves the administration of anticancer drugs.
• Radiation may also be used to combat the growth of invasive cancers.
• Genetic changes can occur at many levels, from gain or loss of entire chromosomes to a mutation affecting a single DNA nucleotide.
• Cancer is one of the most common and severe diseases seen in clinical diagnosis.
• Cancer is fundamentally a genetic disease.
• Cancer is a name used to describe the more virulent form of neoplasia, a disease process characterized by uncontrolled cellular proliferation leading to a mass or tumor (neoplasm).
• The probability of developing one of the six most common cancers in the United States is listed in the table.
• Regulation of the cell cycle involves tumor suppressing genes which encode proteins that normally function to inhibit cell division and are inactivated to cause cancer, and proto-oncogenes which encode proteins that promote cell division and are genes that normally help cells grow and divide to make new cells.
• A tumour is a cluster of cells resulting from rapid cell growth and can be any mass of abnormal cells.
• There are two types of tumour: benign (non-cancerous) and malignant (cancerous).
• Benign tumours are characterized by the cells dividing at an abnormally high rate but remaining in the same location, and are composed of cells that will not invade other unrelated tissues or organs of the body.
• Dysplasias are a type of benign cell growth that have an abnormal appearance and are not cancerous but are worrisome because they have the potential to go through changes that lead to malignant cancers.
• When examined under the microscope, dysplasias often have enlarged cell nuclei and a disorderly appearance, meaning they have irregular shapes and sizes relative to other cells of the same type.
• Treatment of benign growths (including dysplasias) varies widely depending on the size of the tumor, its potential for growth, the location of the growth, and the probability that cell change may lead to malignancy.
• Lymphomas develop in glands that fight infection (lymph nodes and glands scattered throughout the body).
• Familial cancers are not the result of inherited gene mutations, but individuals with familial cancers tend to have a family history of the same type of cancer.
• Cancer involves both inherited and environmental factors, with inherited factors including specific genes that predispose us to cancer and environmental factors causing new mutations such as exposure to high radiation, some viruses (HBV, HCV, HPV), lack of physical activity, smoking, and others.
• Leukemias, related to sarcomas, are cancers of the blood.
• Sporadic cancers are not the result of inherited gene mutations and typically develop later in life, often as a result of environmental exposures and the accumulation of mutations that occur during a person’s lifetime.
• Hematopoietic/Lymphoid tissue is spared throughout the bone marrow lymphatic system and peripheral blood.
• Myelomas start in the bone marrow.
• Treatment for cancer may involve surgical removal of the tumor, surrounding tissues, and lymph nodes.
• Sarcomas are associated with connective tissue (such as muscle) and bone.
• Malignant tumors are difficult to distinguish from normal tissue due to their inability to demarcate where the tumor ends and normal tissue begins.
• Carcinomas are associated with skin, nervous system, gut, and respiratory tract tissue.
• The more abnormal the cells appear, the more likely it is that the tumor may be invasive and able to metastasize.
• Hereditary cancers are the result of gene mutations that are passed from parent to child, and those who inherited the disease-causing mutation have a significantly increased chance of developing cancer and are also at a higher risk of multiple tumors, which frequently occur at an earlier age than sporadic tumors.
• Malignant cells tend to have large nuclei and the cells themselves are usually larger than normal.
• Cells of malignant tumors often resemble tissues from embryos or stem cells rather than normal “mature” cells.
• Malignant cells tend to look very different from the cells they arise from.
• Malignant tumours are characterized by cancer cells’ rapid growth, invasion into neighboring tissues, and the tendency to metastasize.
• Cancer can come back after treatment (cancer recurrence) and can be life-threatening.