Cancer an Overview

Question 1

What causes cancer?

Answer 1

Cancer is a disease where mutations to genes promote abnormal cellular proliferation. Tumors result when suppression genes fail, allowing unrestrained growth.

Question 2

What are proto-oncogenes and oncogenes?

Answer 2

Proto-oncogenes: Normal genes that regulate growth and differentiation.

Oncogenes: Mutated forms of proto-oncogenes that cause cancer by promoting uncontrolled cell division.

Question 3

What is the role of tumor suppressor genes in cancer development?

Answer 3

Tumor suppressor genes (anti-oncogenes) normally control cell growth. When mutated or turned off, they allow the malignant process to flourish.

Question 4

During which phases of the cell cycle are cells most sensitive to radiation?

Answer 4

Cells are most sensitive to radiation during the G2 and M phases of the cell cycle.

Question 5

What factors influence tumor growth?

Answer 5

1. Tumor growth is influenced by damaged genes (oncogenes)
2. Blood supply: tumors can establish their own blood vessels through a process called angiogenesis. Angiogenesis: Tumors stimulate the formation of new blood vessels. Vasculogenic mimicry: Tumor cells form blood vessels themselves. Blood vessel co-option: Tumors take over existing blood vessels.
3. The absence of programmed cell death (apoptosis).

Initially, growth is exponential but slows as the tumor outgrows its nutrient supply.

Question 6

How are tumors classified?

Answer 6

Tumors are classified by their:

Anatomic site (e.g., head, neck, breast, lung, digestive, respiratory, integumentary, bone & cartilage, soft tissue, CNS, Urinary, lymphatic, endocrine)

Cell of origin (e.g., epithelial aka carcinomas, connective tissue aka sarcomas, leukemias from white blood cells, lymphomas from lymphocytes, )

Biologic behavior (benign or malignant).

Question 7

What are the main types of carcinomas?

Answer 7

Squamous cell carcinoma: Arises from cells that form linings (e.g., skin, respiratory tract).

Adenocarcinoma: Arises from glandular epithelial cells, common in colorectal and lung cancers.

Question 8

What is the TNM staging system?

Answer 8

T: Tumor size

N: Lymph node involvement

M: Metastasis
Each component is graded from 0 to 4, with higher numbers indicating more advanced disease.

Question 9

What is the purpose of radiation therapy?

Answer 9

Radiation therapy is a local treatment, using external beam or internal brachytherapy to kill cancer cells. It is also used for palliation, providing relief when a cure is no longer possible.

Question 10

What are radiosensitizers and radioprotectors?

Answer 10

Radiosensitizers: Drugs that enhance the effects of radiation by making cancer cells more sensitive to treatment.

Radioprotectors: Agents that protect normal cells from the damaging effects of radiation.

Question 11

1. Knowledge of cancer dates back to which of the following?
   a. 1600 BC Egypt
   b. 1600 AD England
   c. 400 BC Greece
   d. 1900 AD Germany

Answer 11

ANS: A
The first known observations of cancer date back to 1600 BC Egypt.