Mass Spectrometry and Tumour Marker Analysis in Oncology

What is mass spectroscopy?

A powerful analytical technique used to identify unknown compounds, determine concentrations of known substances, and study molecular structure and chemical composition.

What are the three main components of a mass spectrometer?

Ionization source, mass analyzer, and ion detection system.

What is the function of the ionization source in mass spectrometry?

To convert molecules into gas phase ions that are manipulated into the mass analyzer.

What types of samples can be analyzed using electron and chemical ionization?

Gases and vapors.

What types of samples can be analyzed using electrospray ionization and matrix-assisted laser desorption/ionization?

Liquid and solid biological samples.

What is the role of the mass analyzer in mass spectrometry?

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

Name two types of mass analyzers.

Time of flight and quadrupole.

What does the ion detection system do?

Measures separated ions and sends data to produce a mass spectrum.

How is mass to charge ratio (m/z) calculated?

By dividing the atomic or molecular mass of an ion by the number of charges that the ion bears.

What is the purpose of the inlet system in mass spectrometry?

To introduce a micro amount of sample into the ion source for ionization.

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

A technique where a solid mixture of analyte and matrix is ionized by laser light to produce gaseous ions.

What is the role of the nitrogen laser in MALDI?

To create photons that vaporize the matrix and lift analyte ions into a gas phase plume.

What is the significance of the MALDI technique being considered an offline ionization technique?

Because the sample is purified, deposited, and dried on the sample plate before analysis.

What does MALDI-TOF stand for?

Matrix-Assisted Laser Desorption Ionization Time of Flight.

How does MALDI-TOF assist in clinical microbiology?

By identifying colonies of bacteria or fungi quickly through protein profile analysis.

What is diagnostic sensitivity in relation to tumor markers?

A measure of how often the assay detects the biomarker when the disease is present.

What is diagnostic specificity?

The probability that a laboratory test will be negative in the absence of disease.

What does a test with 100% specificity indicate?

It 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 is positive or absent when the test is negative.

How is the predictive value for a positive test calculated?

It is related to the number of true positive tests.

What is the importance of understanding sensitivity, specificity, and predictive value?

These terms are crucial for evaluating the clinical usefulness of biomarkers.

What is the typical output of a mass spectrometer?

A mass spectrum showing m/z ratios plotted along the x-axis and relative abundance on the y-axis.

What happens to ions of different masses in the mass analyzer?

They are separated and strike the detector at different times.

What is the role of the detector in mass spectrometry?

To amplify the small ion current produced by the ions striking it.

What is the significance of the time of flight (TOF) in mass spectrometry?

It determines the m/z ratios by measuring how long ions take to travel to the detector.

What is the function of the column retention time in chromatography?

It helps in identifying substances before they are ionized and analyzed by mass spectrometry.

What is the relationship between m/z and abundance in a mass spectrum?

m/z is plotted on the x-axis and abundance on the y-axis to represent the ion distribution.

What is cancer?

A cluster of diseases involving alterations in multiple genes that confer a survival advantage and allow for unchecked proliferation.

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

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

What is a biomarker?

A molecule that can be detected in plasma and body fluids, often associated with malignancy.

How are tumor markers used in cancer diagnosis?

They support diagnosis but are not primarily used for it; they can indicate the need for further testing.

What is the significance of tumor markers in monitoring treatment?

A decrease in tumor markers indicates effective treatment, while an increase suggests treatment failure.

What are some advantages of using tumor markers?

Aid in diagnosis, determine response to therapy, serve as prognostic indicators, and indicate relapse.

What are the disadvantages of tumor markers?

High variability in patient samples, lack of reliability, and they may not be present in early-stage cancer.

What advancements have improved the detection of tumor markers?

Advances in genomic and proteomic technology, including next-generation sequencing and immunoassay technology.

What is the role of enzymes in tumor marker detection?

Early assays used serum enzyme activity levels, which improved with the development of immunoassays.

What is CEA and its clinical usefulness?

Carcinoembryonic antigen (CEA) is elevated in various cancers and is primarily used to monitor therapy and detect recurrence.

What cancers are associated with elevated levels of CEA?

Colorectal, lung, gastric, breast, pancreatic, ovarian, and uterine cancers.

What is Neuron Specific Enolase (NSE)?

A glycolytic enzyme whose serum levels correlate with cancer stages, useful for prognosis.

What cancers are associated with elevated levels of NSE?

Small cell lung carcinoma, neuroblastoma, pheochromocytoma, carcinoid tumors, medullary carcinoma, and pancreatic endocrine tumors.

What is the function of Alkaline Phosphatase (ALP) as a tumor marker?

It dephosphorylates compounds and is elevated in liver cancer and bone-related cancers.

What is the role of Creatine Kinase (CK) in cancer detection?

It plays a role in energy production and is elevated in small cell lung carcinoma and prostate cancer.

What does Lactate Dehydrogenase (LDH) indicate in cancer?

It correlates with tumor mass and helps predict response to treatments.

What is β-human chorionic gonadotropin and its significance?

A hormone secreted by placental tissue, used to monitor treatment and progression of trophoblastic disease.

What cancers are associated with elevated levels of β-human chorionic gonadotropin?

Trophoblastic tumors, nonseminomatous testicular tumors, seminoma, melanoma, breast cancer, GI cancer, lung cancer, and ovarian cancer.

What is the role of calcitonin in cancer monitoring?

A hormone produced by the thyroid, useful for monitoring treatment and detecting disease recurrence.

What is the most common type of bladder cancer?

Transitional cell carcinoma

What hormone is produced by corticotrophic cells of the anterior pituitary gland?

Adrenocorticotropic hormone

Why is early detection of colorectal cancer crucial?

It is crucial for treatment.

What is the primary tumor marker for breast cancer?

CA 15-3

What does CA125 indicate in ovarian cancer?

It is used for monitoring recurrence and differential diagnosis of pelvic masses.

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

It is useful to determine the recurrence of pancreatic cancer.

What is the role of carcinoembryonic antigen (CEA) in colorectal cancer?

It is used to monitor therapy and detect recurrence.

What does the presence of Guanylyl Cyclase C (GC-C) in blood indicate?

It may indicate a cancerous growth in the intestinal mucosa.

What is the function of Nuclear matrix protein-22 (NMP-22)?

It is involved in DNA replication and is elevated in bladder cancer.

What is Neuron Specific Enolase (NSE) used for?

It correlates with the stages of cancer and may provide prognosis.

What is the clinical application of HER2-neu in breast cancer?

It is a prognostic and predictive marker for monitoring response to chemotherapy.

What is the significance of measuring serum levels of CA 72-4?

It is potentially useful for diagnosing and monitoring gastric cancer.

What does Prostate Specific Antigen (PSA) help detect?

It helps detect early stage prostate cancer.

What is Alpha fetoprotein (AFP) used for?

It is a tumor marker for hepatocellular carcinoma and germ cell tumors.

What type of cancer is associated with CA 242 and CA 125?

Gallbladder cancer

What is the role of CYFRA 21-1 in lung cancer?

It is useful for detection, therapeutic monitoring, and prognosis of non-small cell lung carcinoma.

What is the common clinical presentation of gallbladder carcinoma?

Initial clinical presentation is non-specific, making early diagnosis difficult.

What does the term 'carcinoid tumors' refer to?

A type of slow-growing cancer that can arise in several places throughout the body.

What is the significance of measuring serum levels of CA 549?

It is a tumor marker used in breast cancer monitoring.

What is the function of vascular endothelial growth factor (VEGF) in cancer?

It promotes the growth of blood vessels to supply tumors.

What is the primary use of measuring IL-6 and IL-8 in ovarian cancer?

They are investigated as potential biomarkers.

What is the role of Kallikreins in cancer diagnostics?

They are being studied as potential biomarkers for various cancers.

What does the presence of β-hCG indicate in germ cell tumors?

It is used for classifying and staging germ cell tumors.

What is the importance of monitoring serum HER2-neu levels?

It helps in monitoring patients' response to treatment with Herceptin.

What is the significance of serum levels of CA 19-2?

It is used in the diagnosis and monitoring of gastric cancer.

What is the clinical application of measuring SCCA in lung cancer?

It is used for the differential diagnosis of non-small cell lung carcinoma.

What is the primary role of tumor markers in cancer management?

They are used for diagnosis, monitoring treatment response, and detecting recurrence.