Oncology Basics Flashcards
What is cancer?
Changes in a single renegade cell that gives rise to uncontrolled, unorganized, and purposeless growth of that cell line
Any cell in body
Malignant cell properties (6 things)
Self-sufficiency in growth signals Insensitivity to anti-growth signals Evasion of apoptosis Limitless replicative potential Sustained angiogenesis Tissue invasion and metastasis
What is Malignant Transformation?
Mutation or epigenetic change: altering the genetic code of a somatic cell endowing it with limitless replicative potential or another growth or survival advantage
3 Events That Lead to Malignant Transformation
Initiation: initial change
Promotion: more mutations or changes, can be stimulated by initiating agent or normal growth factors or hormones (ex: Sun)
Progression: more mutaitons towards more malignant phenotype (population of cancer cells doing this to themselves)
Malignant Transformation: Change that leads to aberrant differentiation (4)
Activation of oncogenes (normal cellular protein, mutation or viral DNA integration into host genome results in activation)
Inactivation of tumor suppressor genes
Altered repair capacity of DNA (genetic mutation)
Defective apoptosis
Benign vs Malignant:
Differentiation
Benign: well differentiated, organized like tissue of origin
Malignant: undifferentiated, cells lack organization
Benign vs Malignant:
Boundaries
Benign: Defined, can be encapsulated
Malignant: Poorly defined, invasive (infiltrative lipoma b/c not encapsulated)
Benign vs Malignant:
Mitosis
Benign: Rare
Malignant: Common
Benign vs Malignant:
Rate of growth
Benign: Slow
Malignant: Fast (aggressive)
Benign vs Malignant:
Clinical Results
Benign: Local compression, hormone production, disfigurement
Malignant: Local destruction, local compression, tumor necrosis, hormone production, disfigurement, metastasis into vital organs
Benign vs Malignant:
Epithelial Glandular Origin
Benign: Adenoma
Malignant: Adenocarcinoma
Benign vs Malignant:
Epithelial Surface Origin
Benign: Polyp, epithelioma, pappilloma
Malignant: Carcinoma
Benign vs Malignant:
Connective Tissue Origin
Benign: Tissue type + oma (fibroma)
Malignant: Tissue type + sarcoma (osteosarcoma, fibrosarcoma)
Benign vs Malignant:
Hemolymphatic
Benign: None
Malignant: Leukemia
& Lymphoma/lymphosarcoma
Tumor Growth
Initially there is high growth factor and mitotic index, short DT
As tumor grows there is low growth factor and mitotic index, prolonged DT
Diagnosis: Sex Predisposition
Males: benign perianal adenomas (intact), testicular tumors (intact), prostate (castrate), osteosarcoma
Females: ovarian, uterine, vaginal, mammary, transitional cell carcinoma
Cats often do not have sex predispositions
Diagnosis: Physical Exam
Examine entire animal not just the obvious problem area
Evidence of pain (lameness, visceral pain, cancer however is not always painful)
Evidence of organ dysfunction (neurologic, icterus, diarrhea, can’t urinate)
Diagnosis: Plan
CBC, Chem, UA (evaluate all organs)
Chest radiographs (common place for metastisis and many things can hide in chest)
Ultrasound, CT, MRI
Note: presence of a mass does NOT diagnose cancer (could be a cyst, granuloma, abcess)
Diagnosis: Cytology
Aspiration and/or tattoo (move needle around while in the mass)
Not always diagnostic
Before sending slide off make sure there are cells on the slide
Diagnosis: Cytology
Criteria for Malignancy
Anisokaryosis Anisocytosis Multiple, irregular, large nucleoli Multinucleation Mitotic figures Altered/variable N:C ratio
Diagnosis: Cytology
3 Basic Cell Types
Epithelial Cells
Mesenchymal Cells
Round Cells
Diagnosis: Cytology
Epithelial Characteristics
Adenomas, Adenocarcionomas
Exfoliate in clumps
Cell-to-cell attachments
Cell walls visible
Diagnosis: Cytology
Round Cells Characteristics
Lymphosarcoma, Mast cell, TVT, some Melanomas
Exfoliate singly
Cell walls easily visible
Round cells with round nuclei
Diagnosis: Cytology
Mesenchymal Characteristics
Soft tissue sarcomas, Osteosarcoma
Exfoliate poorly
Cell borders indistinct
Cells elongate and spindle-shaped (banana)
Nucleus elongated
True or False: A definitive diagnosis can be made from a cytology
False
True or False: It is okay to poke the bladder for cytology if there is a mass present
True
Do not worry about seeding
We take samples from spleen and liver and exit through the peritoneum so why not the bladder
Diagnosis: Histopathology
Incisional
Removal of a small portion of the tumor
Important when treatment would be altered by knowing tumor type or other characteristics
Diagnosis: Histopathology
Excisional
Removal of entire tumor in one procedure
Incisional Biopsy
Advantages
Try and get a bigger piece
Does not require anesthesia (maybe a local block)
Provides diagnosis to next step; planning
Less likely to contaminate clean tissue
Incisional Biopsy
Disadvantages
Requires a second procedure for treatment
Could end up being non-diagnostic
Excisional Biopsy
What is it?
Removal of entire tumor however extent of tumor must be known prior to surgery (typing can help with this) - cytology could give type
Mast cell tumors and sarcomas: large resection needed
Benign or low grade tumors do not require large resection area
Excisional Biopsy
Advantages
Biopsy and therapy can be achieved in a single procedure
Excisional Biopsy
Disadvantages
Anesthesia needed
Requires careful planning to avoid a second surgery or an angry owner; if not all debulked can come back with avenges
What neoplasia is diagnostic via cytology?
Lymphoma
