Cancer Imaging & Types of Cancer

• X-Rays use electromagnetic radiation to produce two-dimensional images.
• They are used to examine bones, teeth, lungs, breasts, heart, blood vessels, and the digestive tract.
• CT scans produce cross-sectional (3D) images of bones and soft tissues.
• CT scans can image bone, soft tissue, and blood vessels simultaneously using radiation.
• MRI uses powerful magnets and radio waves to produce detailed images of soft tissue.
• MRI produces cross-sectional images and are often used to examine the brain, spine, joints, abdomen, blood vessels, and pelvis.
• MRI should not be used on patients with metal implants.
• Bone scans are nuclear imaging tests.
• Bone scans produce two-dimensional images of the body.
• Bone scans are used to examine the skeleton for abnormalities.

Cancer

• Cancer is the uncontrolled growth of abnormal cells in tissues that can spread to other parts of the body.

Types of Cancer

• Carcinomas are the most common type, affecting epithelial cells.
• Carcinomas are commonly found in the skin, lungs, breast, and colon.
• Sarcomas affect bone and soft tissues.
• Sarcomas are commonly found in fat, bone, and muscles.
• Lymphomas affect lymphocytes (T cells or B cells), which are part of the immune system.
• Lymphomas are commonly found in lymph nodes.
• Leukemias affect the bone marrow and is commonly known as blood cancer.
• Leukemias do not form solid tumors.

How Cancer Spreads

• Invasion is the direct migration and penetration of cancer cells into surrounding tissues.
• Metastasis is the indirect migration and penetration of cancer cells into lymphatic and blood vessels to invade tissues in other parts of the body.

Tumor Suppressor Genes (TSGs) and Oncogenes

• TSGs are normal genes that slow down cell division, repair DNA mistakes, or signal cells to die.
• When mutated, TSGs cannot perform their functions, resulting in uncontrolled cell growth.
• Proto-oncogenes are genes that normally help cells grow.
• Oncogenes are mutated proto-oncogenes that cause cells to grow out of control.

The p53 Gene and Cancer

• p53 normally shuts down cell division when a cell is stressed.
• When DNA is damaged, p53 activates genes that stop cell growth or trigger cell death.
• The transactivation domain (red) allows p53 to activate other genes.
• The DNA binding domain (green) is responsible for p53’s ability to read DNA properly; most mutations in the p53 protein found in cancers are in this domain.
• The complexing domain (yellow) is responsible for bringing four individual p53 molecules together.
• MDM2 is a molecule that regulates p53 and is a product of an oncogene.
• When bound to p53, MDM2 prevents p53 from properly binding to DNA to activate other genes.

Gene Expression

• Gene expression refers to the activity level of genes in a cell.
• When genes are turned on, mRNA is expressed.
• In cancer, one or more genes are mutated, causing a change in gene expression.
• Scientists compare mRNA expression of genes in healthy and unhealthy cells to identify mutated genes.
• Upregulated genes have more mRNA.
• Downregulated genes have less mRNA.
• Red indicates genes more expressed in cancer cells, and green indicates genes more expressed in healthy cells
• cDNA microarrays are tools used to study which genes are active in a sample.
• cDNA is made from mRNA.
• The process involves converting mRNA from the sample into cDNA, labeling the cDNA with a fluorescent dye, hybridizing the cDNA on a chip with spots of DNA matching specific genes, and scanning to see which spots light up, showing which genes are active.
• cDNA arrays help scientists see which genes are turned on or off in different conditions.

Risk Factors for Cancer

• Behavioral risk factors include diet, drug and alcohol use, and physical activity.
• Environmental risk factors include radiation exposure, chemicals, bacteria, and viruses.
• Genetic risk factors include the inheritance of mutated genes.

Types of Skin Cancer

• Basal cell carcinoma is found on the lower epidermis, is slow-growing, and rarely spreads.
• Squamous cell carcinoma is found in the squamous layer of skin and can spread if not treated.
• Kaposi sarcoma cancer severity is mid-range.
• Merkel cell carcinoma is rare, fast-growing, and found in hormone-producing cells below skin and hair follicles, with a high severity.
• Melanoma is found in melanocytes where the dermis meets the epidermis and is the most aggressive form, with a high severity.

Skin Cancer Detection

• The mnemonic ABCDE is used: Asymmetry, Border, Color, Diameter, Evolution.

Lag Time

• Lag time is the time between exposure to a carcinogen and cancer development.
• Dependencies include the amount, dose, or intensity of exposure, length of exposure, type of carcinogen, type of cancer, age of exposure, gender, and genetic susceptibility.

Viruses and Cancer

• Epstein-Barr virus is associated with Burkitt’s lymphoma.
• Human papillomavirus (HPV) is associated with cervical cancer.
• Hepatitis B virus is associated with liver cancer.
• Human T-cell lymphotropic virus is associated with adult T-cell leukemia.
• Kaposi’s sarcoma-associated herpesvirus is associated with Kaposi’s sarcoma.

Basal Cell Carcinoma Stages

• Stage 0: Originates in the stratum basale of the epidermis and contains keratinocytes.
• Stage 1: Has spread beyond the epidermis and may extend into the dermis.
• Stage 2: Tumors are larger than 2 cm, thick, but have not spread to nearby organs or lymph nodes.
• Stage 3: May have spread into the bones of the face or into nearby lymph nodes.
• Stage 4: Can be larger than 3 cm thick and has metastasized to more than one lymph node, potentially affecting additional facial bones.

Apoptosis

• Apoptosis is programmed cell death.
• Apoptosis helps regulate the number of cells and prevent damaged cells from replicating.
• Intrinsic and extrinsic pathways initiate apoptosis.
• Cells are broken down from within by proteins called caspases.
• For apoptosis to occur, caspases need to be activated.

Extrinsic Apoptosis Pathway

• The initial signal comes from outside the cell, like immune cells.
• Lymphocytes have surface molecules known as FasL.
• The pathway starts when FasL binds to the Fas receptor on the surface of the target cell, creating a DISC.
• The sequence is mediated by FADD (helper protein).
• Caspases activate each other through the caspase cascade.
• Apoptosis then initiates as the cascade begins the breakdown of cellular materials.

Intrinsic Apoptosis Pathway

• Initiated by signals within the cell.
• Regulated by maintaining a balance between Bcl-2 and Bcl-x (antiapoptotic), and Bax and Bak (proapoptotic).
• In damaged cells, BCL-2 and BCL-X levels are higher.
• In healthy cells, BAX and BAK levels are higher.
• In healthy cells, pro-apoptotic proteins bind to anti-apoptotic proteins, blocking their actions.
• TSGs block BCL-2 and BCL-x.
• In damaged cells, Bcl-2 and Bcl-x are blocked, therefore Bax and Bak are able to drill into the mitochondria, allowing Cytochrome C to leak out.
• Cytochrome C then binds to Apaf-1 proteins, creating a DISC and activating the caspase cascade.

Meiosis

• During meiosis, chromosomes exchange DNA (crossing over).
• Crossing over results in genetically diverse gametes.
• Creates Short Tandem Repeats (STR).
• STRs are usually found within noncoding regions but can be found in coding regions sometimes.
• STRs tend to be associated with specific alleles.

Marker Analysis

• Crossing over likelihood is high you received the allele if you present with the specific STR length.
• Repeat length is connected to allelic expression and will vary from person to person.
• BRCA genes code for TSGs.
• BRCA1 repairs double-stranded DNA breaks.
• BRCA2 repairs single-stranded DNA breaks.
• Mutations lead to a large increase in cancer risk.
• Categories of Cancer: Sporadic, Familial, and Hereditary.

Cancer Screening Guidelines

• No screenings needed for those 35 and below if there are no risks or problems.
• Colon cancer: 45-75
• Breast Cancer: 40 to 44 if they want, 45 every year
• Cervical cancer: after 25 every 5 years
• Lung Cancer: 50 to 80
• Breat cancer : 55 every 2 years
• Prostate Cancer: 50

Human Papilloma Viruses (HPVs)

• HPV is a sexually transmitted infection.
• HPV causes abnormal cells to start growing and eventually can turn into cancer cells.
• HPV is the main cause of cervical cancer.
• HPV is linked to mouth and throat cancer.
• There is a vaccine available that protects against 4 types of the HPV virus.

Epstein-Barr Virus (EBV)

• EBV is a type of herpes virus known for causing infectious mononucleosis (commonly known as "mono").
• EBV infects and stays in B lymphocytes.
• EBV infection increases a person's rick of developing nasopharyngeal cancer and Burkitt lymphoma.
• EBV is also linked to Hodgkin diseases and stomach cancer.
• No vaccine or medications are available.

Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV)

• Both viruses are known to cause liver infection.
• The long-term infection caused by these viruses increase a person’s chance of developing liver cancer.
• There is a vaccine available to prevent HBV infection.
• There are a few medications available that are effective in treating HBV and HCV infections.

Medical Procedures

• Endoscopy is a medical procedure used to examine the inner lining of the throat, esophagus, stomach, and small intestine.
• EGD is a test to examine the lining of the esophagus, stomach, and first part of the small intestine.
• Colonoscopy is a medical procedure to examine the inner lining of the rectum and large intestine.
• Mammography is a type of X-ray imaging technique used for the screening and diagnosis of breast cancer.
• Transesophgeal echocardiogram is a type of ultrasound that takes picture of your heart from the food tube that runs beside your heart on the inside of your chest.

Cancer Treatments

• Surgery involves the removal of the tumor and surrounding tissues during an operation.
• Surgery works best for solid tumors that are contained in one area.
• Surgery cannot be used for blood cancer or other cancers that spread.
• Chemotherapy uses drugs to kill cancer cells by targeting and killing fast-growing cells.
• Chemotherapy unable to differentiate between healthy and cancer cells
• Radiation therapy uses high doses of radiation to kill cancer cells and makes small breaks in the DNA, keeping the cancer from growing or dividing.
• Radiation therapy is a local treatment, only affecting parts of the body being treated.
• Immunotherapy takes advantage of the body’s own immune system to fight cancer cells by teaching the immune system to recognize and destroy cancer cells more accurately.
• Targeted therapy prevents cancer from growing and spreading and is developed to specifically target certain parts of the cell and the signals that are needed for a cancer to develop and keep growing.
• Targeted therapy used only for patients with specific cancers whose tumors have the specific gene mutation that codes for the target.
• Hormone therapy stops or slows the growth of cancer cells that use hormones to grow such as prostate and breast cancers.
• Hormone therapy slows the growth, lessens the chance that the cancer will return and reduces symptoms.
• Stem cell transplant procedures restore the blood-forming stem cells in people who have had theirs destroyed by cancer treatments.
• Precision therapy is an approach to disease treatment and prevention that takes into account individual variability in genes, environment and lifestyle of each person.
• Allows doctors to select treatment that are most likely to help patient based on a genetic understanding. It is tailored to the mutations in each type of cancer
• Clinical trial are medical research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans.
• Nanotech is used to ensure all cancer cells are targeted, deliver cancer drugs.
• The threshold for nanotechnology is less than 100 nanometers.