8. Mass Spectroscopy and Tumor Markers

What is mass spectrometry (MS)?

A powerful analytical technique used to identify unknown compounds and analyze molecular structure.

What are some applications of mass spectrometry?

Detecting drugs, steroids, causes for damaged genes, dioxins, proteins, and metabolites.

What are the three main components of a mass spectrometer?

Ionization source, mass analyzer, ion detection system.

What does the ionization source do in mass spectrometry?

Converts molecules to gas phase ions for analysis.

What are the two main techniques for ionization in mass spectrometry?

Electron and chemical ionization; electrospray and matrix-assisted laser desorption/ionization.

How does the mass analyzer function in mass spectrometry?

Sorts ions based on their mass to charge ratio (m/z).

What is the purpose of the ion detection system in mass spectrometry?

Measures the separated ions and produces a mass spectrum.

What are some separation techniques combined with mass spectrometry?

Gas chromatography, liquid chromatography, capillary electrophoresis.

What is the mass to charge ratio (m/z) in mass spectrometry?

The ratio obtained by dividing the atomic or molecular mass of an ion by its charge.

What does a mass spectrum represent?

Plots mass to charge ratios on the x-axis against relative abundance on the y-axis.

How is pentane ionized in mass spectrometry?

Broken into various cations with specific masses upon ionization.

What is matrix-assisted laser desorption ionization (MALDI)?

A technique where a sample is mixed with a matrix and ionized using laser light.

What is the role of the matrix in MALDI?

Helps to absorb laser energy and assist in the ionization of the sample.

What is the time of flight (TOF) mass analyzer used for?

Determining m/z ratios based on the time it takes ions to travel to the detector.

What is diagnostic sensitivity in the context of tumor markers?

The measure of how often a test detects a biomarker when the disease is present.

What does 100% diagnostic specificity indicate?

The test will always be negative when the patient does not have the disease.

What is the predictive value of a test?

The probability that a disease is present when the test result is positive.

What does Bayes' theorem help calculate?

The probability of an event based on prior knowledge of conditions related to the event.

How does Bayes' theorem relate to medical testing for cancer?

It helps in calculating the likelihood of having cancer given a positive test result.

What are the three main classes of genes altered in cancers?

Proto-oncogenes, tumor suppressor genes, and DNA repair genes.

What are tumor markers?

Molecules that can be detected in plasma and body fluids, associated with malignancy.

What role do tumor markers play in cancer diagnosis?

They support diagnosis but are not primarily used for cancer diagnosis.

What is alkaline phosphatase (ALP)?

An enzyme that dephosphorylates compounds; elevated in various cancers.

What does elevated creatine kinase (CK) indicate?

Potentially indicates small cell lung carcinoma or prostate cancer.

What is lactate dehydrogenase (LDH)?

An enzyme involved in energy production, elevated in many cancers.

How is β-human chorionic gonadotropin utilized in cancer diagnostics?

To monitor treatment and detect recurrence of trophoblastic tumors.

What does elevated calcitonin indicate?

May indicate thyroid carcinoma, carcinoid tumors, and some lung cancers.

What is prostate-specific antigen (PSA)?

A marker used to detect early-stage prostate cancer and assess treatment response.

What is CA 15-3?

A carbohydrate antigen used as a tumor marker in breast cancer.

Why is HER2-neu important in breast cancer?

It is a prognostic marker that can predict treatment response.

What does CA125 indicate?

A glycoprotein used to monitor ovarian cancer recurrence and assist in diagnosis.

What role does carcinoembryonic antigen (CEA) play in colorectal cancer?

It is used primarily to monitor therapy and detect recurrence.

What is the importance of CA 19-9 in pancreatic cancer?

It helps to determine recurrence of pancreatic cancer before clinical symptoms appear.

What are bladder tumor antigen (BTA) and nuclear matrix protein-22 (NMP-22) used for?

Markers for bladder cancer used to measure recurrence.

What type of cancer is most commonly associated with neuron-specific enolase (NSE)?

Small cell lung carcinoma.

What is the significance of measuring CYFRA 21-1 levels?

Useful for detection of non-small cell lung carcinoma and therapeutic monitoring.

What is the role of CA 72-4 in gastric cancer?

A biomarker used for diagnosis and monitoring of gastric cancer.

What can CA 242 indicate regarding gallbladder cancer?

It is a biomarker potentially useful for preoperative evaluation of gallbladder cancer.

What are the advantages of using tumor markers in clinical practice?

Aid in diagnosis, monitor response to therapy, and indicate relapse.

What are the disadvantages of tumor markers?

Patient sample variability, unreliability, and lack of specificity.

What impact do newer technologies have on tumor marker testing?

They provide more powerful assays for better cancer detection and monitoring.