Neoplasia and Cancer Basics

Neoplasia (Tumors)

• A tumor is a new growth of tissue, often forming a mass. A malignant neoplasm is cancer.
• Neoplasia means "new growth" (neo-plasia).

Cancer

• Cancer is uncontrolled cell division of genetically abnormal cells that spread locally and to distant sites.
• Cancer development involves an interaction between environmental factors and a susceptible host.
• Normal cells divide as needed, attach to other cells, stay in place, and commit suicide (apoptosis) when no longer needed. Cancer cells do not stop dividing, detach, and can invade other tissues.

Cancer Cell vs. Normal Cell Differences

• Cancer cells lack specialization compared to normal cells.
• Cancer cells ignore programmed cell death (apoptosis) signals.
• Cancer cells impact the surrounding tissue (microenvironment) and may evade the immune system.

Cancer Causes (DNA Damage)

• Environmental factors (e.g., tobacco, radiation, UV rays, viruses).
• Endogenous causes (e.g., reactive oxygen species (ROS), metabolic processes).
• Random DNA Replication Errors
• Protective measures (DNA repair enzymes, apoptosis) are often bypassed in cancerous cells.

Gene Mutations

• Gene mutations permanently alter DNA, leading to abnormal proteins or preventing proper protein formation.
• Acquired mutations are most common, occurring during a person's lifetime. Sporadic cancers result.
• Germline mutations are less common, inheritable (from parent to child), and related to inherited cancers, which account for 5% - 20% of cancers.

Genes Linked to Cancer

• Tumor Suppressor Genes: Protect by monitoring cell division, repairing DNA, and regulating apoptosis. Recessive mutations diminish their function, leading to cancer.
• Oncogenes: Genes that promote cell growth. Dominant mutations increase their function, leading to uncontrolled growth & cancer.

Classification of Tumors

• Behavior: Benign (slow growth, no spread), In Situ (localized), Malignant (uncontrolled, spreads), Unknown.
• Tissue of Origin: Epithelial (cells lining organs, glands), Connective tissue (bone, cartilage, fat).

Microscopic Criteria of Malignant Cells

• Undifferentiated cells (anaplastic): Lacking normal tissue characteristics.
• Atypical/pleomorphic: Varying in size and shape.
• Hyperchromasia: Darker, increased DNA content in the nucleus.
• Increased N/C ratio: Larger nucleus compared to cytoplasm.
• Prominent nucleoli: Larger nucleoli in the nucleus.
• Loss of polarity: Disorganized arrangement.
• Abnormal Mitosis: Irregular cell divisions.

Methods of Spread of Malignant Tumors

• Local invasion: Tumors spread directly into surrounding tissues.
• Blood spread: Tumors enter blood vessels to spread to other parts of the body, forming emboli.
• Lymphatic spread: Tumors travel via lymphatic vessels to regional lymph nodes.

Transcoelomic Implantation

• Spread of tumors through body cavities like the peritoneum.

Cancer Stem Cells (CSCs)

• Stem cells within tumors.
• Drive tumor formation and recurrence.
• Less common but highly tumorigenic.

Important Tumor Characteristics

• Angiogenesis (blood vessel formation) is crucial for tumor growth.
• Tumors secrete factors to promote angiogenesis, bypass the normal regulation, and form new blood vessels to feed the tumor, leading to tumor growth and metastasis.

Papilloma

• Benign epithelial tumors, associated with HPV. Grossly appear as cauliflower-like growths.

Adenoma

• Benign tumor originating from glandular tissue. Present as a rounded or polypoid growth.

Carcinoma

• Malignant epithelial tumor. Grossly appears as a fungating/polypoid mass, or infiltrating or ulcerative.

Teratoma

• Tumor of embryonic germ cells. Consists of tissues from multiple germ layers.

Hamartoma

• Focal malformation with abnormal tissue mixture.

Para-neoplastic Syndromes

• Disorders caused by tumor-produced substances (e.g., hormones, cytokines). Examples include Cushing syndrome and hypercalcemia.

Growth Disturbances

• Hyperplasia: Increased cell number.
• Hypertrophy: Increased cell size.
• Atrophy: Decreased organ size/cell size.
• Metaplasia: Change in one tissue type to another.
• Dysplasia: Abnormal cellular development.

This quiz covers the fundamental concepts of neoplasia and cancer, including the characteristics of tumors and the differences between cancer cells and normal cells. It also explores the causes of cancer, emphasizing the role of environmental factors and DNA damage in its development.