Introduction to the Oncology Care Unit

- General Overview of Cancer

What is a Tumor in the Body?

A tumor is a mass or group of tissues that results from the accumulation of abnormal cells due to the abnormal growth of tissues. Not all tumors are cancerous; they can be benign or malignant (cancerous). Tumors can spread from one organ to another. The size of tumors varies; they can range from a small lump to a large mass, depending on the type of tumor.

Types of Tumors:
Tumors are divided into three types:

1. Benign Tumor:
Benign tumors are non-cancerous and usually do not spread to other organs, or if they do, it is very slow. These tumors are generally not dangerous, but if they grow large and press against important parts of the body, such as nerves or blood vessels, they may cause pain or damage. Typically, once removed, benign tumors do not return.

Examples of benign tumors include:

Adenomas, treated surgically.

Lipomas, the most common type of benign tumor in adults, growing from fat cells and treated by liposuction in the area.

Myomas, which usually affect the uterus and stomach, treated with medication or surgery.

Nevi (moles), which are skin growths that can be pink, brown, or black. Any change in size, shape, or color requires medical consultation.

Papillomas.

2. Premalignant Tumor:
Premalignant tumors are non-cancerous but have the potential to turn into malignant tumors at any moment, and they must be monitored regularly.

Examples of premalignant tumors include:

Actinic Keratosis, abnormal skin growth usually affecting those with fair skin, with increased risk due to prolonged sun exposure.

Cervical Dysplasia, often detected by a Pap smear, caused by the Human Papillomavirus (HPV). This growth may transform into cancer in 10-30 years, leading to cervical cancer.

3. Malignant Tumor:
Malignant tumors are cancerous and often spread to other organs due to the rapid growth of cells. These tumors are generally life-threatening.

Examples of malignant cancerous tumors include:

Carcinoma, which can affect the stomach, prostate, pancreas, lungs, liver, colon, and breast, being the most common type of malignant tumor.

Sarcoma, which affects cartilage, bones, fat, and nerves.

Germ Cell Tumor, which typically affects the ovaries and testes, and the cells producing sperm and eggs, but can also affect the brain and abdomen.

Blastoma, more common in children, leading to tumors in the brain, eye, and nervous system.

The table below outlines the main distinguishing features of benign and malignant tumors.

Distinguishing Features

Malignant Tumor

Benign Tumor

1. Cell Features

Cells are undifferentiated and often poorly resemble the normal cells of the tissue they originated from.

Cells are well-differentiated and resemble the normal cells of the tissue they originated from.

2. Growth Method

Grows in the periphery, sending out processes that infiltrate and destroy surrounding tissues.

Grows by expansion and does not infiltrate surrounding tissues.

3. Growth Rate

Growth rate varies and depends on the level of differentiation. The more mutated the tumor, the faster its growth.

Growth rate is usually slow.

4. Spread

It reaches blood and lymphatic channels, spreading to other parts of the body.

Does not spread.

5. General Effects

Often causes systemic effects like anemia, weakness, and weight loss.

Usually localized, and does not cause systemic effects unless its location interferes with vital functions.

6. Tissue Destruction

Often causes widespread tissue damage due to tumor growth exceeding blood supply or obstructing blood flow to the area; may also produce substances that damage cells.

Generally does not cause tissue damage unless its location interferes with blood flow.

7. Ability to Cause Death

Usually causes death unless its growth can be controlled.

Does not usually cause death unless its location interferes with vital functions.

Distinguishing Features	Malignant Tumor	Benign Tumor
1. Cell Features	Cells are undifferentiated and often poorly resemble the normal cells of the tissue they originated from.	Cells are well-differentiated and resemble the normal cells of the tissue they originated from.
2. Growth Method	Grows in the periphery, sending out processes that infiltrate and destroy surrounding tissues.	Grows by expansion and does not infiltrate surrounding tissues.
3. Growth Rate	Growth rate varies and depends on the level of differentiation. The more mutated the tumor, the faster its growth.	Growth rate is usually slow.
4. Spread	It reaches blood and lymphatic channels, spreading to other parts of the body.	Does not spread.
5. General Effects	Often causes systemic effects like anemia, weakness, and weight loss.	Usually localized, and does not cause systemic effects unless its location interferes with vital functions.
6. Tissue Destruction	Often causes widespread tissue damage due to tumor growth exceeding blood supply or obstructing blood flow to the area; may also produce substances that damage cells.	Generally does not cause tissue damage unless its location interferes with blood flow.
7. Ability to Cause Death	Usually causes death unless its growth can be controlled.	Does not usually cause death unless its location interferes with vital functions.