Laboratory Diagnosis of Cancer

1. Histological methods

2. Cytopathology - FNAC/Exfoliative

3. Immunohistochemistry/ EM

4. Molecular diagnosis

5. Tumor Markers

Histological methods - Frozen

SectionUsed per-operatively

• To determine nature of mass lesion - whether inflammatory / benign / malignant• To evaluate sentinel node status, margins of excised cancer

Cytological Methods - Fine Needle Aspiration Cytology

• Using regular small bore needle : readily palpable sites – breast, lymph node, thyroid

• Using special needle: prostate• Using ultrasound/CT guidance: deep seated

structures also

Cytological Methods - Exfoliative

Cytology

• Pap smears : Carcinoma cervix

• Ascitic / pleural fluid cytology

• Cerebrospinal fluid

Immunohistochemistry

• Categorizing undifferentiated malignancies

• Categorizing leukemia / lymphomas

• Determining site of origin of metastasis

• Detecting molecules of prognostic / therapeutic significance

Immunohistochemical stains Carcinomas: Cytokeratin, EMA, CEA

Sarcomas: Vimentin Muscle derived sarcomas: Desmin, Actin Tumors of endothelium: Factor VIII, CD31

Leukocyte malignancies1. CD 45: LCA (Leukocyte common antigen) - almost all except mature RBCs2. CD 19, 20: B Cell Lymphoma3. CD 3, 5, 7, 4, 8: T cell Lymphoma4. CD 15+, CD30+ : Hodgkin’s Lymphoma

Neural crest derived tumors: S100 +ve 1. Neuroendocrine tumors(carcinoid) : S 100 & Chromogranin 2. Neural tumors (neuroblastoma) : S-100 & NF +ve 3. Melanoma : S-100 & HMB45 +ve 4. Small cell carcinoma : S100 & NSE

Miscellaneous: Mesothelioma: Calretinin, Medullary carcinoma of thyroid: Calcitonin, Myeloma: kappa/lambda light chains, Prostate carcinoma: PSA, Hepatocellular carcinoma: AFP, Trophoblastic tumors: HCG, Gastrointestinal stromal tumors: CD117 (c-Kit), Mantle cell lymphoma: Cyclin D1

7CD 19

1. Lymphoma

2. Neuroblastoma

3. Rhabdomyosarcoma

4. Melanoma

A 49-year-old man complains of pain in his left thigh for 3 months. On physical examination his thigh is increased in size, compared to the right. A plain film radiograph reveals the presence of a 15 cm solid mass that does not appear to arise from bone, but it does have infiltrative margins. A biopsy of this mass is taken, and on microscopic examination the mass is composed of highly pleomorphic spindle cells. Which of the following immunohistochemical markers is most likely to be demonstrated in the cells of this mass?

A Cytokeratin B Factor VIII C Alpha fetoprotein D Lambda light chain E Vimentin

9

S100

If also positive for

1. NF - ?

2. Chromogranin - ?

3. HMB45 - ?

Molecular diagnosis

• Cytogenetic analysis• PCR assays ( polymerase chain reaction)• FISH ( fluorescent in-situ hybridisation)• Tissue arrays

Useful in diagnosis, prognosis Minimal residual disease, To detect hereditary predisposition to cancer

Flow Cytometry

• Rapid quantitative analysis of cell features like membrane antigens, DNA content

• Identification of cell surface antigens in leukemias/lymphomas

• Ploidy analysis in solid tumours

TUMOR MARKER ASSOCIATED CANCER

AFP Hepatocellular carcinoma, yolk sac tumor (endodermal sinus tumor) of ovary or testis

Bence Jones protein

Multiple myeloma, Waldenström's macroglobulinemia (represent light chains in urine)

CA 15-3 Breast carcinoma

CA 19-9 Pancreatic, colorectal carcinomas

CA 125 Surface-derived ovarian cancer (e.g., serous cystadenocarcinoma; helpful in distinguishing benign from malignant tumors)

CEA Colorectal and pancreatic carcinomas (monitor for recurrences)

LDH Malignant lymphoma (prognostic factor for response to standard therapy)

PSA Prostate carcinoma (also increased in prostate hyperplasia)

CEA (Carcinoembryonic Antigen)

• Glycoprotein, produced by embryonic tissue of gut/pancreas/liver

• Increased in Cancer of Colon, Pancreas, Breast • Also increased in benign disorders – alcoholic cirrhosis,

hepatitis, ulcerative colitis• Useful in postoperative detection of residual disease /

recurrence of colon cancer, monitoring treatment of breast cancer

AFP (Alpha Feto-Protein)

• Glycoprotein, produced by yolk sac/fetal liver/GIT• Increased in Cancer of liver / germ cell tumors of testes• Also increased in benign disorders – alcoholic cirrhosis,

hepatitis, toxic liver injury, pregnancy• Useful in post-therapy measurement – index of response

to therapy / recurrence

Electron microscopy in cancer• Carcinomas: Tonofilaments, desmosomes• Neuroendocrine tumors: Secretory granules• Malignant melanoma: Melanosomes• Langerhan cell histiocytosis: Birbeck granules• Insulinoma: Crystal containing granules

Required reading: Robbins Basic Pathology 9E, p207-213

Recommended reading: Robbins and Cotran Pathologic Basis of Disease 8E, p323-327