Chapter 6 - Neoplasms Flashcards
Neoplasm
- An autonomous cellular proliferation occurring without respect to the needs of the host
• Benign or malignant
Oncology
Study of neoplasms
Tumor
Mass or lump, usually referring to a neoplasm
Malignant
A process that will probably kill the patient if left alone
For cardinal features of malignant neoplasm
- Undifferentiated cells: abnormal maturation (anaplasia)
- Uncontrolled cell growth: unchecked proliferation
- Invasive: nonencapsulated
- Meta-stasis: spread too distant sites (multiple tumors)
• Blood vessels, lymphatic vessels
Cancer
Non-specific term that refers to a malignant neoplasm
- Carcinoma: malignant tumors of epithelial origin
- Sarcoma: malignant tumors from mesenchymal (non-epithelial, except for mesenchymal endothelium and mesothelium)
Cancer exceptions
- Fibrosarcoma: easily curable by surgically resection – noninvasive
- Basal cell carcinoma: invades aggressively, but very rarely metastasize
- Carcinoid tumor: neuroendocrine, mainly G.I. and a long
Benign
Any process that is not malignant
Benign features
- Semi differentiated cells: more closely resemble their tissue of origin (slight anaplasia)
- Encapsulated: tumors with well defined borders, grow locally do not invade or metastasize
- One tumor: usually
Benign exception
- Can kill if in critical location:
• Meningeoma - exert pressure on brain
• Ependymoma - block CSF circulation
• Myxoma - block mitral valve and orifice in left atrium
• Insulinomas - cause lethal hypoglycemia
• Pleomorphic adenoma - aggressive growth that defies surgical cure
Tumor prefixes
Refer to the tumor tissue of origin
- Squamous: resembling squamous epithelium
- Adeno: with glandular configurations
- Hemangio: endothelial cell origin (blood vessels) – mesenchymal
- Leiomyo: smooth muscle origin
Tumor suffixes
Identify tumor as benign or malignant
- Oma: benign tumor of glandular origin (adenoma - tumor of glandular origin)
- Carcinoma: malignant tumor of epithelial origin (adenocarcinoma - malignant tumor of glandular origin)
- Sarcoma: malignant tumor of mesenchyme origin (fibrosarcoma - malignant tumor of fibrous CT)
Carcinogenesis
The cause of all cancer is damage DNA
Normal cell cycle
- Resting: normal, nondividing function
- Preparation for division: synthesizing DNA
- Mitosis: division into two daughter cells
Density dependent reproduction of cells
Only enough new cells are made to meet body needs
Neoplasia
Density independent cell reproduction, is not controlled by body needs
Growth fraction
Proportion of cells that are reproducing at any one time
Doubling time
Amount of time it takes a tumor to double it cell population
Abnormal cellular changes in neoplasia
- Loss of cell recognition
- Loss of cell adhesion
- Loss of contact inhibition
- Last of differentiation
Loss of cell recognition
- Neoplastic cells may lose a normal anti-genic qualities
- Neoplastic cells may develop new antigens (neoantigens)
Loss of cell adhesion
Neoplastic cells tend not to stick together
Loss of contact inhibition
Neoplastic cells will pile up on top of each other
Loss of differentiation
- Normal cells have specialized differentiated for a particular function
- Neoplastic cells usually lose some of this specialization
• Well differentiated cells – still resemble the cell of origin (benign tumors)
• Poorly differentiated or undifferentiated cells appear immature (anaplasia) and may not resemble their cell of origin (malignant tumor)
Carcinogen
Something that increases the risk of developing a cancer
Co-carcinogen
Something that increases the activity of a carcinogen
Pro – carcinogen
Something that must be changed (activated, modified, metabolized) before it becomes a carcinogen
Mutagen
Substance that can change the genetic material of the cell
Chemical carcinogen
- Polycyclic aromatic amines
- Aromatic amines
- Nitrosamines
- Dioxin
- Aflatoxin
Polycyclic aromatic amine
Products of combustion
- Cigarette smoke (benzopyrene)
- Automobile exhaust or smog (benzene)
Aromatic amines
Guys, moth repellent (napthalene), insecticides
Nitrosamines
Produced in the body from nitrates; nitrates are in some preservatives and other food additives
Dioxin
1 most carcinogenic chemicals
Aflatoxin
1 most carcinogenic biological substance (aspergillus flavum)
- And contaminated peanuts and grain, causes hepatocarcinoma
Physical carcinogens
- Ionizing radiation
- Ultraviolet radiation
- Asbestos fibers
Ionizing radiation
- Survivors of the atom bomb and nuclear accident
- Excess x-ray exposure
Ultraviolet radiation
From excess sun exposure
Absestos fibers
Exposure causes mesothelioma
- Once widespread as an insulator in construction
- Concrete workers, heavy construction workers may risk exposure
Oncogenic viruses
Viruses that cause tumor formation
- HPV
- Herpes type 2
- Hepatitis B
- EBV (Epstein-Barr virus)
- Retrovirus
HPV
A papilloma is a type of epithelioma
- Causes common warts and venereal warts
- Some HPV subgroups that cause venereal warts increased risk of developing squamous cell carcinoma of cervix, penis, anus and now
Herpes type 2
Causes cervical cancer – cervical carcinoma
Hepatitis B
Causes serum hepatitis
- Increases risk of developing carcinoma of the liver: Hepatocarcinoma
Epstein – barr virus (EPV)
Causes infectious mononucleosis
- Associated with:
• Burkitt lymphoma and Africa
• Nasopharyngeal carcinoma and Asia
Retroviruses
RNA core - must be transcribed into DNA to enter host cells genetic material
- Associated with some leukemias
- HIV (AIDS) virus is a retrovirus, but doesn’t cause cancer
Other carcinogenic risk factors
- Diet
• High fat low fiber diet = colon carcinoma
• Nitrates in water and food = stomach cancer - Sexual activity: early sexual activity with multiple partners = cervical carcinoma
- Hormones: increased estrogen = carcinoma breast or endometrium
- Habits or substance-abuse:
• Alcohol = esophageal carcinoma
• Tobacco = long, throat, kidney, bladder cancer - Family history or genetics
• Breast and colon carcinoma’s
• neurofibromatosis (NF or von Recklinghausen dz) 5% neurofibrosarcomas
• Identical twin: develop tumor of the same type at same time if they live together
Signs and symptoms of malignancy “Caution”
C - hange in bowel or bladder habits A - non healing store U - nusual bleeding or discharge T - hickening or lump I - ndigestion (persistent) O - bvious change and mall N - agging hoarseness or cough
Diagnosis of malignancy
- History and physical examination
- Radiological examination
- Laboratory tests
History and physical examination
About 70% of causes can be diagnosed this way
Radiological examination
- X-ray: chest, G.I. tract (barium studies), mammography
- CT scans and MRI
Laboratory tests
- Blood counts, blood smears, bone marrow examination
- Urinanalysis, stool examination
- Chemical studies: increased levels of some chemicals during tumor formation
- Psychology: pap smears, etc.
- Biopsy: allows one to determine invasiveness of cancer
Criteria of malignancy
- Invasiveness
- Ability to metastasize
Invasiveness
Tumor extends into surrounding normal tissues and may eventually replace and destroy those tissues
- Carcinoid tumor is our invasive, but very slow growing
Ability to metastasize
Spread distantly
- Hematogenous/vascular spread
- Lymphatic spread
- Implantation “seeding”
Hematogenous/vascular spread
By way of blood vessels
- Usually first mode of metastatic spread by sarcomas
Lymphatic spread
By way of lymphatic vessels and lymph nodes
- Usually first mode of metastatic spread by carcinomas
Implantation “seeding”
On surfaces of body cavities
- Carcinoma of ovary: spreads five fluid and abdominal cavity to other surfaces in abdomen
Factors promoting invasion and metastasis
- Rapid growth rate
- Greater mobility of neoplastic cells
- Decreased adherence to adjacent cells: normal cells usually stick to their neighbors; malignant cells break away
- Decreased contact inhibition: normal cells generally stop growing when they run into an adjacent cells; malignant cells don’t
Histologic characteristics of malignancy
Microscopic appearance is often useful to determine malignancy
- Dysplasia
- Anaplasia
- Evidence of abnormal growth
Dysplasia
Premalignant
Anaplasia
Abnormal appearance of cells reflecting failure of maturation
- Irregular shape (pleomorphism)
- Variation in size
- Increased amounts of chromosomal material (hyperchromatism)
Evidence of abnormal growth
- Increased numbers of mytotic figures
- Necrosis
- Infiltrated growth pattern (invasion)
Prognosis of malignancy
- Grading
- Stages
Grading
Appearance of tumor; a microscopic judgment by pathologist
- Grade I: well differentiated, low-grade malignancy, mostly mature cells, good prognosis
- Grade II: moderately differentiated
- Grade III: moderately differentiated
- Grade IV: poorly differentiated, high-grade malignancy, immature cells, poor prognosis
Stages
Anatomic extent of tumor, a clinical judgment by pathologist
- Stage 0: non-invasive, can cure by surgery
- Stage I: tumor still localized to one region or organ
- Stage II: intermediate spread, depends on location of tumor
- Stage III: intermediates spread, depends on location of tumor
- Stage IV: tumor has metastasized and is widespread
Treatment of malignancy
- Surgery
- Radiation
- Chemotherapy
- Immunotherapy
Surgery
Mainstay of treatment
- # 1 choice: get rid of as much as the tumor as possible
Radiation
- Shrink large tumors before operating on them
- Kill tumor left behind after surgery
- Treat inoperable tumor is, including unresectable metastatic site
- An adjunct with other modalities
Chemotherapy
- Treat metastatic tumors
- An adjunct with other modalities for some primary tumors
Immunotherapy
- Attempt to improve immunity (interferon, BCG)
- Magic bullet: toxic agents attached to antibodies directed against tumor
Effects of malignancies
- Metabolic competition
- Mechanical obstruction
- Destruction of vital tissues
- Hemorrhage
- Infections
- Others
Metabolic competition
Tumor competes with normal tissues for nutrients resulting in malnutrition of the patient (cachexia)
Mechanical obstruction
Tumor occludes vital passageways (trachea, colon, bile duct)
Hemmorhage
Leads to anemia and susceptability to infection due to:
- Decreased platelets (marror replaced by tumor)
- Decreased coagulation factors (liver replaced by tumors)
- Disseminated intravascular coagulation (DIC: tumor emboli in blood activate coagulation)
- Ulceration: increased hemorrhageing
Others
- Depression
- Hormonal imbalance (carcinoid tumors: neuroendocrine, secrete serotonin)
Total cancer deaths
20% of all deaths in USA, 2nd to cardiovascular
Cancer death rate
Male: #1 Lung #2 Prostate #3 Colon
Female: #1 Lung #2 Breast #3 Colon
Cancer incidence
Male: #1 Prostate #2 Lung #3 Colon
Female: #1 Breast #2 Lung # 3 Colon
Dropping death rate
- Stomach and colon cancer
- Female: breast and uterine cancer as well
