Tumor Marker – Part 1 – Definition of Tumor Markers, Staging and Grading
Definition of Tumor Marker
- Tumor markers are the biochemical or immunological counterparts of differentiation state of the tumor.
- Tumor markers represent the expression of the substances produced normally by embryogenically related tissues.
- Tumor markers are the substances found in increased concentration in malignancies in:
- Body fluids.
- Body tissues.
- Tumors markers can be measured:
- Tumors markers can be measured by:
- Chemical methods.
- Immunological methods.
- Molecular biological methods.
- An ideal tumor marker should be both specific and sensitive to detect small tumors in the early stages.
- But unlikely this is not the situation.
- These are found in different tumors even origin from one source.
- These are present in high concentration in malignancies than the benign tissue.
Advantages of tumor marker
- The tumor markers help in the diagnosis, prognosis, and monitoring of the tumor.
- Help in the determination of the progression of the disease.
- Help in the monitoring of the tumor after the treatment.
- It can be used for the Screening of the general population.
- These are helpful for the Clinical staging of the tumors.
- Help for the Evaluation of the success of the treatment.
- Very useful for the Detection of recurrence of the tumor.
- Helpful to decide the immunotherapy.
Staging and Grading
The most common is the TNM classification. This is depending upon the spread of the tumor.
- T = Primary tumor size.
- N = Lymnodal status is the regional lymph nodes involvement.
- M = Metastasis of the tumor describes the distant spread of the tumor.
- Primary tumor size:
- TX = The Main tumor cannot be measured.
- T0 = Main tumor cannot be found.
- T1 = Size, and extent of the tumor.
- T2 = same as above
- T3 = same as above
- T4 = same as above. As the T1 to T4, similarly, the tumor size increases.
- Lymph nodes status:
- N0 = There is no tumor infiltrate in the near regional lymph nodes.
- N1 to N3 = Indicates the number of lymph nodes involved.
- Distant metastasis:
- M0 = No distant metastasis found.
- M1 = Positive for distant metastasis.
- This is the histologic appearance of the tumor cells how abnormal these tumor cells seen under the microscope.
- This will indicate how the tumor will grow and spread.
This is the histologic differentiation of the tumor. This may be:
- When the tumor cells and organization are near the normal cells and the tissue.
- These tumor cells grow and spread at a slow rate.
- Moderately differentiated.
- Poorly differentiated. When the tumor cells are abnormal and fast-growing.
The tumors are graded as:
- Grade 1, when the tumor cells are near to the normal tissue.
- Grade 2, when the tumor cells slightly away from the normal tissue.
- Grade3, when the tumor cells grow rapidly and faster.
- Grade 4, when the tumor cells grow more rapid and abnormal-looking than the normal tissue.
- The grades are:
- G1= Well-differentiated and low grade.
- G2 = Moderately differentiated and are intermediate grade.
- G3 = Poorly differentiated and are high grade.
- G4 = Undifferentiated and are high grade.
- The latest classification is followed given by the College of the Americal pathologist.
TNM classification objectives are:
- This will help in treatment planning.
- This will give the idea about the prognosis.
- This will evaluate the treatment result.
- It will facilitate the exchange of information between the centers.
- It supports cancer control activities, including cancer registries.
- This will contribute to the investigations of human malignancies. (Source = UICC)