Cancer: Diagnosis

1. Frozen Section

• the sample is quick frozen and sectioned, permitting histological evaluation within minutes

• useful for determining the nature of a breast lesion or in evaluating the margins of an excised cancer during surgery to see if the entire neoplasm has been removed

2. Immunohistochemistry

• Powerful adjunct to routine histology

• Detection of cytokeratin by specific monoclonal antibodies labeled with peroxidase points to a diagnosis of undifferentiated carcinoma rather than large cell lymphoma

3. Fine Needle Aspiration

• Aspiration of cells from a mass, followed by cytologic exam of the smear

• Commonly used with readily palpable lesions affecting the breast, thyroid, lymph nodes, and salivary glands

4. Cytology ~ Papanicolaou Smear

• Used widely for the discovery of carcinoma of the cervix, often at an in situ stage, but also used with endometrial carcinoma, bronchogenic carcinoma, bladder and prostate tumors, and gastric carcinomas

• Neoplastic cells are less cohesive than others, and are shed into fluids and secretions ; the shed cells are evaluated for features of anaplasia indicative of their origin in cancer

5. Flow Cytometry

• Used routinely in the classification leukemias and lymphomas

• Fluorescent antibodies against cell surface molecules and differentiation antigens are employed to obtain the phenotype of malignant cells

• Also useful in assessing DNA content (ploidy) of tumor cells

6. Tumor Markers ~ CEA, PSA

• Biochemical assays for tumor associated enzymes, hormones, and other tumor markers in the blood cannot be construed as modalities for the diagnosis of cancer, but can contribute to finding cases (screening) and in some instances are useful in determining the effectiveness of therapy

• PSA

  • prostatic carcinoma can be suspected with elevated blood levels

  • PSA levels may also be elevated in benign prostatic hyperplasia

  • Elevations in PSA are not diagnostic of an underlying cancer

• CEA

  • Radioimmunoassay for circulating hormones may point to the presence of tumors in the endocrine system

  • CEA, normally produced in the embryonic tissue of the gut, pancreas, and liver, is a complex glycoprotein that is elaborated by many different neoplasm

  • The level of elevation is correlated with the body burden of tumor so that the highest levels are found in patients with advanced metastatic disease

  • CEA elevations have been reported in may benign disorders, thus CEA assays lack specificity and sensitivity required for the detection of early cancers

  • Most useful in providing presumptive evidence of the possibility of colorectal carcinoma because this tumor yields the highest levels and is useful in the detection of recurrences after excision

7. Molecular Profiling

   • DNA microarray analysis allows simultaneous measurements of the expression levels of several thousand genes

   • Process begins by extraction of mRNA from any two sources (ex. normal and malignant, normal and preneoplastic, or of the same histological type) and cDNA copies of the mRNA are synthesized in vitro with fluorescently labeled nucleotides

   • For each sample, the expression level of thousands of genes is obtained, and by using bioinformatics tools, the relative levels of gene expression in different samples can be compared

   • Basically, a molecular profile is generated for each tissue analyzed

Category: Pathology Notes