Differences Between Tumours
Definition
Tumour
A tumour is an abnormal mass of cells resulting from uncontrolled cell division.
- Not all tumours are the same.
- They differ in their growth rates, ability to spread, and potential to cause cancer.
You do not need to memorise the term "apoptosis," just understand what it means.
Benign Tumours Are Localized and Non-Cancerous
- Growth Characteristics:
- Slow-growing and often remain localized.
- Cells are usually well-differentiated, resembling normal cells.
- Invasion and Metastasis:
- Do not invade nearby tissues or spread to other parts of the body.
- Encapsulated by a fibrous tissue, which keeps them contained.
- Health Impact:
- Generally harmless unless they press on vital organs or nerves.
- Can often be removed surgically with a low risk of recurrence.
Don’t assume all tumours are cancerous. Only malignant tumours cause cancer, while benign tumours do not.
Primary vs. Secondary Tumours
- Primary Tumour
- The original site where abnormal cell division begins.
- Can be benign or malignant.
- Secondary Tumour
- Formed when malignant cells spread from the primary tumour to other parts of the body.
- Always malignant and indicate metastasis.
- Secondary tumours retain the characteristics of the primary tumour.
- For example, breast cancer cells in the liver are still breast cancer cells, not liver cancer cells.
Not All Tumours Cause Cancer
- The key difference lies in the ability to invade and spread:
- Benign tumours: Do not cause cancer.
- Malignant tumours: Cause cancer due to their invasive and metastatic nature.
Remember: Benign = Non-cancerous, Malignant = Cancerous.
The Mitotic Index is Used to Observe Cell Division
Definition
Mitotic index
The mitotic index is the ratio of the number of cells in mitosis to the total number of cells observed.
- The mitotic index measure the proportion of cells undergoing mitosis in a tissue sample.
- This helps assess the growth rate of tumours.
How to Calculate the Mitotic Index
- Count the number of cells in mitosis.
- Count the total number of cells.
- Use the formula:
$$\text{Mitotic Index} = \frac{\text{Number of cells in mitosis}}{\text{Total number of cells}}$$
Self review- What is the difference between a primary and a secondary tumour?
- How does the mitotic index help differentiate between benign and malignant tumours?
