3. Histological diagnosis
Microscopic tissue examination is the gold
standard of cancer diagnosis.
• The specimen must be adequate,
representative and properly preserved.
Several sampling approaches are available:
• Excision or biopsy
• fine-needle aspiration
• Cytologic (papanicolaou) smears
• Immunocytochemistry
• Flow cytometry
4. Excision or biopsy
• Awareness in selecting appropriate site for biopsy
• In case of large mass: the margins may not be
representative and the center may be largely
necrotic.
• Frozen-section: quick technique permits histologic
evaluation within minutes
– determining the nature of lesion
– Evaluating the margins of an excised cancer to
ascertain that the entire neoplasm has been
removed.
5. Excision or biopsy
• in breast biopsy, frozen-section allows
determination of whether the lesion is malignant
and may require wider excision or sampling of
axillary lymph nodes for possible spread
6. Fine-needle aspiration
• It involves aspiration of cells from a mass,
followed by cytologic examination of the smears.
• Useful for palpable lesions affecting the breast,
thyroid, lymph nodes, and salivary glands
• With modern imaging techniques it can be
extended to deeper structures (liver, pancreas,
and pelvic lymph nodes)
7. Cytologic (papanicolaou) smears
• It is used widely for detecting cervix carcinoma
at an in situ stage.
• It is also used for endometrial carcinoma,
bronchogenic carcinoma, bladder and prostate
tumors.
• Neoplastic cells are less cohesive than others
and so are shed into fluid or secretion
• The shed cells are evaluated for anaplastic
features
8. Immunocytochemistry
tumor markers
• Monoclonal antibodies against cytokeratin
present in epithelial cells (undifferentiated tumor
rather than large cell lymphoma)
• PSA for prostatic metastasis
• Estrogen receptor and Her2 in breast cancer
• Carcinoembryonic antigen (CEA): abnormal
increase are seen in colorectal Ca, Gastric CA,
Pancreatic Ca, Breast Ca.
• Alpha fetoprotein: increased in liver cancer,
colorectal Ca, pancreatic Ca, lung Ca, and
cancer arised from germ cells of testes.
9. Flow cytometry
• Routine classification of leukemias and
lymphomas
• Fluorescent antibodies against cell surface
molecules and differentiation antigens.
• Assessing DNA content of the tumor cell
10. Biochemical assays
• Useful for measuring the levels of tumor
associated enzymes, hormones, and tumor
markers in serum.
• Useful in determining the effectiveness of
therapy and detection of recurrences after
excision
11. Molecular diagnosis
• Polymerase chain reaction (PCR)
example: detection of BCR-ABL transcripts in
chronic myeloid leukemia.
• Fluorescent in situ hybridization (fish)
it is useful for detecting translocation characteristic
of many tumors
• Both PCR and Fish can show amplification of
oncogenes (HER2 and N-MYC)