Unit 2: Cancer Basics & Risk Factors

leading site for cancer cases

- men: prostate

- women: breast

leading site for cancer death

- men: lung

- women: lung

cancer is the result of ...

- the derangement of control pathways that usually keep cell growth in check

neoplasia

- process of abnormal and uncontrolled growth of cells

- benign or malignant

neoplasm

- abnormal mass of tissue as a result of neoplasia

- growth is uncoordinated with that of normal tissues

- persists after cessation of stimuli

tumor

- now means the same as neoplasm

- are clonal (derived from one cell)

oncology

- study of tumors and neoplasms

benign tumors

- gross and microscopic characteristics are innocent

- local and in general can be surgically removed

- can still create issues

- suffix "-oma" is added to cell type

- ex: fibroma, osteoma, lipoma, hemangioma

malignant tumors

- referred to as cancers

- lesion is able to invade and destroy adjacent tissue

- spread to distant sites (metastasis)

- can cause death

mesenchymal tumors

- ends in sarcoma

- mesenchyme could be from CT/bone/lymph/blood

- rare in humans

- ex: chondrosarcoma, rhabdomyosarcoma, liposarcoma

epithelial tumors

- ends in carcinoma

- from epithelial tissues

- ex: adenocarcinoma, squamous cell carcinoma, transition cell carcinoma (urothelial carcinoma)

nomenclature exceptions for malignant neoplasms

- lymphoma

- melanoma

- mesothelioma (cancer of protective lining of internal organs, mesothelium)

- seminoma (germ cell tumor of testes)

- blastoma (blast cells)

teratoma

- originate from totipotent cells (cells that can turn into many things)

- more differentiated: benign

- less differentiated: malignant teratoma/mature teratoma

- can have structures such as teeth, hair, nerve cells, and blood vessels

epidemiology of cancer

- study of the patterns of cancer in populations to help elucidate the origin

- correlate race, environment, cultural differences, and behavior to occurrence

- ex: smoking and connection to lung cancer, high dietary fat and low fiber diet connection to colon cancer

risk factors for development of neoplasms

- lifestyle choices

- geographical factors

- environmental factors

- age

- genetics

- chronic inflammation

environmental risk factors

- being outside (UV light rays, smog)

- medications (ex: methotrexate, used to treat severe psoriasis)

- work (asbestos, vinyl chloride)

- home (alcohol, smoking, high fat diet)

age risk factor

- most carcinomas occur late in life, >55 years (due to decreased immunocompetence, increased accumulation of somatic mutations)

- women age 60-79 cancer primary cause of death

- men age 40-79 cancer primary cause of death

- children 10% of deaths <15 years old is due to cancer, second only to accidents

genetic predisposition to cancer

- less than 10% are inherited cancer syndromes

- usually a point mutation in single allele, but greatly increases risk for tumor development

- tends to arise in specific tissue

hereditary retinoblastoma

- 25-30% of pts with this condition inherit the mutated retinoblastoma gene (10,000 fold increased risk to develop the cancer)

- rare, cancerous tumor of retina

- most commonly diagnosed in children aged 1-2 years

- increased risk for other cancers later in life

hereditary retinoblastoma clinical symptoms

- pupil may appear white or have white spots

- crossed eyes

- double vision

- eyes that do not align

- eye pain and redness

- poor vision

- blindness can occur in affected eye

hereditary retinoblastoma treatment

- for small tumors: laser surgery or cryotherapy

- radiation for both local and larger tumors

- chemotherapy may be needed if tumor has spread

defective DNA repair syndromes

- xeroderma pigmentosum

- hereditary nonpolyposis colorectal cancer

- breast cancer susceptibility

xeroderma pigmentosum

- nucleotide excision repair (NER) enzymes are mutated, important for UV damage repair pathway

- severe sun sensitivity (sunburn with blistering, freckle-like pigmentation on sun exposed areas called Lentigos)

- approx. 25% develop neurological problems

- onset is at young age, with less than 40% of pts surviving past 20 years of age

- increased risk of skin malignancies

- no cure, treatment is avoidance of sun and protective clothing

hereditary nonpolyposis colorectal cancer

- also called lynch syndrome

- mutation in DNA mismatch repair genes (MLH1, MSH2, MSH6, PMS2, or EPCAM)

- prevents proper repair of errors

- high risk of colon cancer as well as overy, stomach, brain, and other cancer types

breast cancer susceptibility

- BRCA 1/2 are involved in DNA repair

- associated with age, increased number of cases in family, ovarian cancer as well as breast cancer, breast cancer in men

- risk increases from 12% in normal population to 60% in BRCA 1/2 are mutated

chronic inflammation risk factor

- increased risk of cancer at sites of inflammation

- ex: ulcerative colitis and viral hepatitis

- maladaptive immune response

- proposed mechanism is chronic inflammation creates a fertile backdrop for neoplastic cells to develop due to growth factors, cytokines, chemokines, etc. promoting survival, tissue remodeling, and angiogenesis