Cancer Development and Treatment

• Cancer involves uncontrolled cell division and differentiation.
• Cancer is defined as a disease affecting multicellular organisms.
• It is also a disease specifically of the cell cycle.
• Cancer cells do not respond normally to cell cycle controls.
• Over one million Americans receive a cancer diagnosis each year.
• A higher predisposition to developing cancer is inherited in about 10% of cases.
• Most cancers, approximately 90%, do not involve genetic changes passed to offspring.
• Carcinogens and lifestyle choices contribute to the causes of cancer.
• Smoking can lead to cancer of the lungs, mouth, throat, bladder, and kidneys, as well as heart disease and stroke.
• Alcohol consumption increases the risk of cancer in the mouth, throat, and other organs.
• Human behaviors, like smoking along with physical inactivity and poor dietary habits, account for 50-70% of cancer deaths in the U.S.
• Smoking alone accounts for 30% of cancer deaths.
• Radiation (X-rays) can also cause cancer.
• About 90% of cancers in humans relate to exposure to carcinogens.

DNA Mutations and Mechanisms

• Carcinogens like UV light and certain chemicals in cigarette smoke, encourage genetic changes in somatic cells.
• DNA alterations can affect gene expression, which affect cell division, and promote to cancer.
• Mutations occur most frequently during DNA replication, caused by mistakes or chemical and physical forces.
• Effects of mutations can be neutral, beneficial (nudge in evolution), or harmful (cell death or cancer). Mechanisms of repair: DNA repair enzymes.
• Normal plant and animal cells have a controlled cell cycle.
• Cancer develops from mutated or damaged genes.
• Proto-oncogenes are normal regulatory genes.
• Mutated or damaged proto-oncogenes are called oncogenes.
• Tumor suppressor genes, are regulatory genes that repress cell growth, division, differentiation, and adhesion; they can be turned off, damaged, or mutated in cancers.

Cancer Stages

• Stage 0: in situ tumor, with abnormal cells only found in the tumor.
• Stages I–III: defined based on cancer type, size, spread, and lymph node involvement.
• Stage IV: cancer has metastasized to distant sites and organs.

Cancer Development

• For cancer to develop, a cell must divide uncontrollably and undergo physical changes to break away from surrounding cells.

Tumours

Characteristics of Benign Tumors:

• Remain in one location.
• Single, well-defined mass.
• May be surrounded by connective tissue. Characteristics of Cancerous Tumors:
• Abnormal cell structure and may appear undifferentiated.
• May spread.
• Edge of the tumor is not clearly defined.

Factors Contributing to Cancer

• Viruses and bacteria account for >15% of all cancers, with chemicals in the environment (e.g., asbestos), radiation (sun - UV B- and radioactive materials), dietary factors (red meat and saturated animal fat), alcohol use and tobacco also being causes.

Lung Cancer

• Is diagnosed in approximately 170,000 men and women each year in the U.S.
• Worldwide, more than 1.2 million cases are diagnosed annually.
• Smoking is attributed to nearly 90% of lung cancer cases.
• Has a high mortality rate due to lack of simple screening tests, leading to late detection. Symptoms of Lung Cancer:
• Early symptoms are nonspecific, such as persistent coughing or recurrent pneumonia/bronchitis.
• Later symptoms include voice change, chest pain, and blood in sputum. Treatments:
• Surgery, often combined with radiation and chemotherapy.

Colon and Rectal Cancers

Symptoms:

• Blood in stool or rectal bleeding. Risk Factors:
• Sedentary lifestyle, obesity, smoking, family history, low-fiber diet, and high-fat diet. Progression:
• start as polyps (benign tumors) that gradually become malignant. Screening Methods:
• Early cancer can be detected through screening tests such as detection of blood in stool specimens and a colonoscopy that examines the interior of the colon with a flexible fiber-optic scope.
• Treatment - polyp and tumor removal

Breast cancer

• Early detection is crucial for survival
• A mammogram, which uses low-dose X-rays, can be used for early detection
• Lump detection during breast exams
• Risk factors that have genetic links (BRCA1 & BRCA2 genes), with increasing age, early menstruation and/or late menopause, obesity after menopause, as well as the use of oral contraceptives and hormone replacement after menopause.

Pancreatic Cancer

• Rarely detected in early stages
• Has the second highest death rate of cancers due to late detection
• Risk factors include genetics (BRCA1 or BRCA2) and smoking

Prostate Cancer

• Is most common after age 50
• Biggest risk factor is advancement in age Symptoms:
• Urination difficulties, blood in urine, and pain in pelvic area. Diagnosis:
• Digital rectal exam, blood test for PSA (prostate-specific antigen), and biopsy can be used. Treatment:
• Surgery, radiation therapy, and hormones may be used to treat

Leukemia

• Is a cancer of immature white blood cells in bone marrow and in the blood
• Chemotherapy can be used to treat Risk Factors:
• Include: Down syndrome, exposure to ionizing radiation, benzene, and infection with HTLV-1 virus
• Can be contracted during childhood and adulthood Symptoms:
• Are often non-specific Diagnosis:
• Blood tests and bone marrow biopsies

Lymphoma

• Is cancer of the lymphoid tissue.
• Includes Hodgkin and Non-Hodgkin Lymphoma Symptoms:
• Enlarged lymph nodes, intermittent fever, itching, night sweats, and weight loss. Risk Factors:
• Altered immune function in transplant recipients, HIV infection, and occupational exposure to herbicides. Treatment:
• Radiation and chemotherapy

Esophageal Cancer

• High Ratio of Deaths to Cases - 92 deaths for every 100 cases Risk Factors:
• Age, alcohol and/or tobacco use, obesity, and chronic gastric reflux.
• Rarely diagnosed at an early stage because symptoms appear when 60% of the circumference of the esophagus is cancerous.

Other Cancers

• Include bladder, uterine, kidney, skin, ovarian and testicular.

The Immune System & Cancer

• Normally, it defends the body against cancers, but cancer cells may not always be recognized as "self".
• Suppression of the immune system can make individuals more susceptible to cancer.

Cancer: Early Detection

• Is advanced through tumour imaging (X-rays, MRI), genetic testing to identify mutated genes, enzyme tests for cancer markers.

Cancer treatments include

• Conventional approaches like surgery, radiation and chemotherapy.
• Radiation therapy damages DNA and disrupts cell division.
• Chemotherapy uses drugs that disrupt cell division.
• Immunotherapy promotes the immune response.
• Starving cancers inhibits angiogenesis (growth of new blood vessels).
• Molecular treatments target oncogenes.

Preventing Cancer

• Know family history.
• Get regular medical screenings.
• Learn self-examination techniques.
• Avoid direct sunlight during peak hours (10 a.m. to 4 p.m.).
• Watch diet and weight.
• Avoid sunlamps and tanning salons.
• Do not smoke.
• Drink in moderation if at all.
• Be informed.
• Exercise regularly.

Explore cancer development, risk factors, and treatment approaches. This includes the characteristics of cancerous tumors, stages, genetic mutations, and body defenses. Also covers radiation and chemotherapy mechanisms.