Cancer Nomenclature
…oma: benign
…carcinoma: malignant epithelial tumor
…sarcoma: malignant mesenchymal tumor
Blastoma: malignant tumor of embryonic cell of origin (mostly in pediatrics)
Polyps-
- Sessile polyp: broad base
- Pedunculated polyp: has a stalk at the base
- Papillary: rose bud appearance around a central core of fibrous/vascular tissue
Exophytic: extend above epithelial surface
Key Features of Squamous Cell Tumors
Intercellular bridges: present in normal epithelium, variable to not evident in cancer
Keratinization: variable to non-existent, hyperkeratotic on surface of whorls, keratin pearls
Dyskeratotic cells: keratinized individual malignant cells, dense eosinophilic staining cytoplasm
Key Features of Adenomatous Neoplasms
Benign neoplasms arising from glandular tissue
Colonic adenoma is a polyp, thyroid adenoma is enclosed in a fibrous capsule, hepatic adenoma forms a small irregular mass that is not encapsulated
Hypercellularity and dark staining (hyperchromatic), increased N/C ratio, loss of polarity
Key Features of Adenocarcinomas
- Glandular: acinar, well to moderate differentiation, glands vary in number and size/shape
- Nests: poor differentiation, can be linear cords
- Sheets of cells: poor differentiation
- Trabecular: poor differentiation
- Papillary: variable differentiation, fibrovsscular core
- Signet ring: poor differentiation, large cytoplasmic mucin vacuole that pushes the nucleus to the periphery
Cancer Grading and Stage
Grade: describes potential aggressiveness, well differentiation is low grade, tumor can contain multiple grades but judge by worst
Stage: describes spread/extent, localized to one area is low stage
Staging is better predictor since considers more far reaching factors
Type of Cancers that Heavily Rely on Grading
Prostate
Breast
Ovarian
Renal
Astrocytomas and other types of brain cancer
B cell lymphomas
Gleason Grade and Score
Take the two most common tumor grades and add scores together, low of 2 and max of 10
Based on gland formation and architecture
1-2: fairly uniform glands with little stroma between, well differentiated
3: moderately differentiated and still see glands, start to spread out more
4-5: glands grow in back to back fashion and appear as large blobs, tumors can also grow as tiny dots
Bloom-Richardson Grading Scale
Grades breast carcinoma
Variables: nuclear grade, mitotic count, tubule formation percentage
Graded from 1-3
Low grade: 3-5
Intermediate grade: 6-7
High grade: 8-9
Cancer Stage
- Size of the primary lesion (T): T1-4 (T0 is no evidence of tumor), size and local extent of primary lesion measured in cm
- Extent of spread to lymph nodes (N): increases as more nodes are involved
- Presence/absence of blood borne metastasis
Mesenchymal Tumors
- Lipoma:circumscription at gross examination, can but don’t have to look different from fat, more eosinophilic between fat drops
- Liposarcoma: bunch of ground substance with spindle shaped cells, have lipoblasts that are like fetal fat cells
- Fibroma: well circumscribed gray-white tumors on gross examination, hypercellular with spindle shaped nuclei, minimal pleomorphism, and few mitotic figures
- Fibrosarcoma: hypercellular, pleomorphic, and increased mitotic figures
- Leiomyoma: smooth muscle like in myometrium, hypercellular, spindle shaped cells/nuclei, few mitotic figures and pleomorphism
- Leiomyosarcoma: pleomorphism and increased mitotic figures
- Chondroma: look similar to normal hyaline cartilage, hypercellularity and some pleomorphism, single or small clusters in blue cartilaginous matrix,have Capillaries while normal hyaline cartilage is avascular
- Chondrosarcoma: high N/C ratio, pleomorphism nuclei, hypercellularity and can be within same lacunae, bluish white on gross examination
- Osteoid Osteoma: discrete oval on X-ray, reddish brown tissue on gross examination, surrounded by Zone of sclerotic bone
- Osteosarcoma: cloudy X-ray, extends into adjacent soft tissue, pleomorphism
Glioblastoma Multiforme
Highly pleomorphic tumor that arises from astrocytes, has necrosis
Increased vascularity, leaky blood vessels give rise to cerebral edema
Germ Cell tumors
Most often in gonads but can be elsewhere
Teratoma: has tissue of all three germ layers, can be squamous epithelium, sebaceous glands, and cartilage
Can have hair and teeth
Case control study
Start in present time, look back to find exposure knowing outcomes like case (diseased) and control (not diseased)
Incident cases are preferred over prevalent cases since prevalence has risk factors that may be more related to survival than disease development
Returns in statistical efficiency diminish dramatically by increasing the control:case ratio beyond 4 or 5
Case Control: Matching
Makes sure that cases and controls are similar on certain characteristics
Individual and group matching
Case Control: Biases
- Selection Bias: need well-defined inclusion/exclusion criteria and sound selection methods to ensure that exposure of cases/controls match exposure from source cohort
- Information Bias-
A. Recall Bias: participants may not be able to accurately exposure info, some cases/controls could be misclassified as exposed/unexposed
B. Interviewer Bias: interviewers might not be blinded to participant status during talks
Exposure status should not be known when a case/control is selected for the study
- Confounding Bias: association between exposure and outcome is distorted by the presence of another variable, of confounding is in the source cohort then should be in the study sample to be representative
Case Control: Strengths and Weaknesses
Strengths: great for rare diseases (prospective cohort for rare exposures), quick and cheap compared to cohort study, can estimate a causal parameter under certain conditions
Weaknesses: hard to select appropriate controls, info bias, not ideal for rare exposures, hard to establish temporality between exposure/disease
