UNIT II. UNDERSTANDING CANCER

What is Cancer?

Cancer is a disease characterized by uncontrolled cell growth, loss of normal regulation, and the ability to invade and metastasize. Cancer arises from DNA damage leading to mutations in genes controlling cell division, apoptosis, and differentiation.

Epidemiology

• Higher incidence in individuals above 65 years old

• More common in males

• Increasing global burden to aging, lifestyle factors and environmental exposures

• WHO/IARC(2022): 20 million new cases less then 9.7 million deaths

Benign Tumors

• Slow growing

• Well differentiated

• Encapsulated

• Non invasive

• Non metastic

Malignant Tumors

• Rapid growth

• Poor differentiated

• Irregular boarders

• Invasive

• Metastic

• High occurence

Proliferative patterns?

1. Hyperplasia

2. Metaplasia

3. Dysplasia

4. Neoplasia

5. Carcinoma in SITU

6. Anaplasia

Hyperplasia

an increase in the number of normal cells within a tissue. Though structurally and functionally normal, the increased cell proliferation may require monitoring depending on location and cause (e.g., hormones, chronic irritation).

Metaplasia

is the reversible substitution of one mature cell type with another, often due to chronic irritation. While not cancerous, it increases the risk of dysplasia and neoplasia if the stimulus persists.

Dysplasia

involves abnormal cellular morphology and disorganized tissue structure. It ranges from mild to severe and may progress to cancer, particularly when high-grade. Dysplastic lesions often require surveillance or treatment.

Neoplasia

is uncontrolled, abnormal cell growth that continues without external stimulus. It may be benign (localized) or malignant (invasive and potentially metastatic). Malignant neoplasms exhibit rapid growth and varying cellular atypia.

Carcinoma in SITU

is a high-grade precancerous lesion where atypical cells remain localized, not breaching the basement membrane. It is often referred to as “stage 0 cancer” due to its potential to become invasive.

Anaplasia

 is a hallmark of malignancy, characterized by undifferentiated, pleomorphic cells with abnormal nuclei and high mitotic rates. It signifies aggressive tumor behavior and poor prognosis.

Invasion and Metastasis

Mechanisms include:

• loss of adhesion

• enzymes release

• lymphatic spread

• hematogenous spread

• seeding into body cavities