Cancer notes

Cancer

Cancer - Malignant, spreading tumor Tumor – any swelling Oncology – study of tumors and their

problems Neoplasm – abnormal tissue growth

resulting in rapid cellular proliferation which continues after growth of normal tissue has stopped or slowed Benign or Malignant

Neoplasms Benign – not inclined to spread or get

worse Less dangerous than malignant tumors but

can compress surrounding tissues and impair their functions as a result of enlargement

Neoplasms Malignant – able to spread and become worse

Cells are more spherical because they don’t adhere to surrounding normal cells

More embryonic, less mature, than normal tissue Invasive, ability to squeeze into spaces and enter

surrounding tissues Secrete enzymes that cut paths through healthy

tissue Grow irregularly, sending processes in every

direction Ability to dislodge, enter blood vessels, lymphatic

vessels or body cavities Travel to distant sites, attach and invade tissues

Genetics of Cancer

Mutations of genes within somatic cells

Occurs during DNA replication Radiation, chemicals, toxins & viruses

cause mutations by damaging or altering DNA

Usually develop in tissues that undergo frequent cell division

Genetics of Cancer

Neoplasm can become cancerous when cell’s structure and functions are changed Increase ability of cancer cells to invade

and destroy surrounding tissue Metastasize Resistant to drug treatments

Genetics of Cancer

Prevention of development in cancer cells: DNA repair enzymes detect and correct

errors during replication Self-destruction mechanism destroys

cells with abnormal DNA (Apoptosis)

Genetics of Cancer Proto-oncogenes – promote cell division Oncogenes – abnormal regulatory genes,

increases rate of cell division Tumor suppressor genes – normal genes

that slow down or stop cell division

Cancer

Metastasis – process by which cancer cells spread to distant sites

Secrete substances that cause blood vessels to grow into the tumor and supply oxygen and nutrients.

Types of Cancer Carcinoma – cancer of epithelial

tissue Basal cell & Squamous cell carcinomas

Adenocarcinoma – gladular epithelium Breast cancer

Sarcoma – connective tissue Osteosarcoma – bones Chondrosarcoma - cartilage

Cancer Therapy Concentrates on confining and killing

malignant cells X-rays, lasers, surgical removal, drugs Problem: Some cancers can’t be removed

completely by surgery or killed Affects normal tissues

Newer drugs prevent blood vessel development

Anticancer therapies – cells that can recognize tumor cells and destroy them

Chemotherapy Any treatment involving chemical agents to

stop cancer cells from growing Eliminate cancer cells at sites great

distances from original cancer More than half receive chemotherapy Administered through a vein, injected into a

body cavity or delivered orally as a pill Destroys cancer cells but does not

distinguish between cancer & healthy cells Eliminates fast growing cells: cancer, hair &

blood cells

Skin Cancer Most common type of cancer Caused by UV rays, chemicals, x-rays,

inflammation, inherited Amount of protective melanin affects skin

cancer Fair-skinned = gen. predisposed to develop

skin cancer Individuals over 50 yrs = increased risk

Skin Cancer

Three major types of skin cancer are: Basal cell carcinoma Squamous cell carcinoma Melanoma

No. 1 Basal Cell Carcinoma Least malignant and most common skin cancer Stratum basale cells proliferate and

invade the dermis and hypodermis Slow growing and do not often

metastasize Can be cured by surgical excision in

99% of the cases

Squamous Cell Carcinoma Arises from keratinocytes of

stratum spinosum Arise most often on scalp, ears, and

lower lip; bleeding can occur Grows rapidly and metastasizes if not

removed; if travels to lymph nodes, can be fatal

Can be treated by radiation therapy or removed surgically

Melanoma Cancer of melanocytes

is the most dangerous type of skin cancer because it is: Highly metastatic Resistant to chemotherapy 77% of skin cancer deaths in U.S. 40% develop in preexisting moles

Melanoma Melanomas have the following characteristics (ABCDE

rule) A: Asymmetry; the two sides of the pigmented area

do not match B: Border is irregular and exhibits indentations C: Color (pigmented area) is not uniform: black,

brown, tan, and sometimes red or blue D: Diameter is larger than 6 mm (size of a pencil

eraser) E: Evolving (lesions change over time) Change size,

shape, elevation or color, bleed, crust or become tender

Melanoma

Treated by wide surgical excision accompanied by immunotherapy

Chance of survival is poor if the lesion is over 4 mm thick

UVA vs UVB

The sun has 2 types of UV (ultraviolet), rays: 1. UVA2. UVB

UVA

UVA - long-wave solar rays of 320-400 nm. Goes through windows, light clothing and

even windshields Responsible for aging Less likely than UVB to cause sunburn UVA penetrates the skin more deeply,

causing wrinkling and leathering of the skin. UVA may also directly induce some skin

cancers, including melanomas.

UVB

Short-wave solar rays of 290-320 nm More potent than UVA in producing

sunburn. Main cause of skin cancers. The"tanning ray", UVB stimulate the

melanocyte cell, producing a suntan as a defense against UV radiation

Skin Cancer prevention

NOT FOOLPROOF BUT IMPORTANT….

wear SUNCREEN!