Introduction:  Immunohistochemistry for Cancer Diagnosis

We have covered the introduction to IHC here

In this post, we will cover in brief  typical IHC profiles for common tumor types in Kenya.

A. Breast Cancer:

1. Cytokeratin 8/18 (CK8/18): Positive in most breast carcinomas, helps identify epithelial origin.
2. Estrogen Receptor (ER) and Progesterone Receptor (PR): Positive in hormone receptor-positive breast cancers, guiding hormonal therapy.
3. HER2/neu (ERBB2): Positive in HER2-positive breast cancers, guiding targeted therapy.
4. Ki-67: Indicates the proliferation rate, helps assess tumor aggressiveness.
5. Epithelial Membrane Antigen (EMA): Positive in adenocarcinomas, confirming epithelial differentiation.

B. Colon Cancer:

1. Cytokeratin 20 (CK20): Positive in colorectal adenocarcinomas, assists in differentiation from other tumors.
2. CDX2: Transcription factor expressed in intestinal epithelium and colorectal adenocarcinomas.
3. Mismatch Repair Proteins (MLH1, MSH2, MSH6, PMS2): Assessing MMR deficiency in Lynch syndrome and sporadic colorectal cancers.
4. CD44v6: Implicated in colon cancer metastasis and invasion.
5. CEA (Carcinoembryonic Antigen): Often elevated in colon cancer, can be used for monitoring.

D. Lung Cancer:

1. TTF-1 (Thyroid Transcription Factor-1): Positive in lung adenocarcinomas, helps distinguish from other lung cancers.
2. P40 or P63: Positive in squamous cell carcinoma of the lung.
3. ALK (Anaplastic Lymphoma Kinase) or ROS1: Detecting gene rearrangements, guiding targeted therapy.
4. PD-L1 (Programmed Death-Ligand 1): Indicates potential response to immune checkpoint inhibitors.
5. Napsin A: Present in lung adenocarcinomas, assists in diagnosis.

E. Prostate Cancer:

1. Prostate-Specific Antigen (PSA): Elevated in prostate cancer, used for detection and monitoring.
2. Androgen Receptor (AR): Expressed in prostate cancer, plays a role in disease progression.
3. P504S (AMACR): Overexpressed in prostate cancer, assists in distinguishing from benign conditions.
4. CK5/6 and p63: Negative in prostate adenocarcinomas, useful for differentiation from basal cell hyperplasia.
5. ERG: Frequently involved in gene fusions in prostate cancer.

F. Gastric (Stomach) Cancer:

1. Hereditary Diffuse Gastric Cancer (HDGC) Markers (CDH1, p120, and others): Indicate hereditary predisposition to diffuse gastric cancer.
2. HER2/neu (ERBB2): Used to guide targeted therapy in HER2-positive gastric adenocarcinomas.
3. CK7 and CK20: Differential expression pattern helps in distinguishing between gastric and colorectal adenocarcinomas.
4. EBV (Epstein-Barr Virus) In situ Hybridization: Detects EBV presence in a subset of gastric cancers.
5. Mucin Markers (MUC1, MUC2, MUC5AC): Assist in identifying different subtypes of gastric adenocarcinomas.

G. Liver Cancer (Hepatocellular Carcinoma):

1. Hepatocyte Paraffin 1 (Hep Par-1): Positive in hepatocellular carcinoma, distinguishes from metastatic tumors.
2. Alpha-Fetoprotein (AFP): Elevated in some cases of hepatocellular carcinoma, used for diagnosis and monitoring.
3. Glypican-3 (GPC3): Expressed in hepatocellular carcinoma, can help differentiate from benign liver lesions.
4. Arginase-1: Expressed in hepatocellular carcinoma and certain other liver tumors.
5. Cytokeratin 7 (CK7): Negative in hepatocellular carcinoma, can aid in differentiation from cholangiocarcinoma.

H. Ovarian Cancer:

1. Wilms Tumor 1 (WT1): Positive in many serous ovarian carcinomas.
2. CA-125 (Cancer Antigen 125): Elevated in some ovarian cancers, used for monitoring and follow-up.
3. PAX8: Expressed in ovarian serous, endometrioid, and clear cell carcinomas.
4. Inhibin: Positive in granulosa cell tumors and some sex cord-stromal tumors.
5. ER and PR: Positive in some ovarian tumors, including low-grade serous carcinomas.

I. Pancreatic Cancer:

1. CK7 and CK20: Used to differentiate between pancreatic and ampullary adenocarcinomas.
2. CA19-9: Elevated in pancreatic cancer, useful for diagnosis and monitoring.
3. CDX2: Positive in ampullary adenocarcinomas, aiding in differentiation from pancreatic cancer.
4. Ki-67: Indicates proliferative activity and can help assess tumor aggressiveness.
5. SMAD4 (DPC4): Loss of expression is associated with poor prognosis in pancreatic cancer.

As always, the choice of markers depends on the specific characteristics of the tumor and the clinical context. The field of cancer pathology is continuously evolving, so the use of IHC markers may change over time based on new research and diagnostic practices.

If you need any clarification or want to discuss your tumor  marker profile, be sure to contact Us for a free consultation