Neoplasia and Oncology Overview

Neoplasia

• Neoplasia is a critical pathology topic. Neoplasms are common and serious diseases.
• A neoplasm is new growth of cells, marked by uncontrolled tissue proliferation.
• Neoplasia (Neo= new; plasia= growth) means new growth.
• A neoplasm involves abnormal and excessive tissue growth.
• The growth of a cancer is uncoordinated with normal surrounding tissue. This growth continues even after the initial cause is removed.

Oncology

• Oncology is the branch of science studying neoplasms (tumors).
• Proto-oncogenes: normal cellular genes that drive cell proliferation.
• Oncoproteins: proteins produced from oncogenes, they drive increased cell proliferation.
• Oncogenes: mutated forms of proto-oncogenes. Changes cause excessive copies or increased activity, leading to uncontrolled cell growth.

Nomenclature

• All tumors (benign or malignant) have two key parts:
• Neoplastic cells: the tumor's core tissue.
• Supportive stroma: fibrous connective tissue and blood vessels, providing structure for the neoplastic cells.

Classifications of Neoplasms

• Benign tumors: slow-growing, localized, and do not spread.
• Malignant tumors: rapidly growing, spread throughout the body, and can cause death.
• Benign tumors are often named with the suffix "-oma".
• Malignant tumors derived from epithelial cells are called carcinomas.
• Malignant tumors derived from mesenchymal cells are called sarcomas.

Examples of Tumors

• Melanoma: carcinoma of the melanocytes.
• Hepatoma: carcinoma of the hepatocytes.
• Lymphoma: malignant tumor of lymphoid tissue.
• Seminoma: malignant tumor of the testis.
• Leukemia: cancer of blood-forming cells.

Characteristics of Tumors

• Rate of growth: is a key difference between benign and malignant tumors.
• Cancer phenotype and stem cells: important for distinguishing benign and malignant tumors.
• Clinical and gross features: visible characteristics.
• Microscopic features: characteristics of cell structure seen with microscopic examination.
• Local invasion: direct spread of cancer into neighboring tissue.
• Metastasis: spread of cancer to distant sites.

Differentiation vs Anaplasia

• Differentiation: extent to which tumor cells resemble normal cells.
• Well-differentiated cancer means the tumor cells look similar to the cells from the area they are found.
• Poorly-differentiated cancer means the tumor cells don't look anything like the cells from the area they're found.
• Anaplasia: lack of differentiation, a hallmark of malignant tumors.

Grading of Tumors

• Tumor differentiation degree is a measure of how similar the cells of the tumor are to the cells they came from.
• Grading: microscopic and gross investigation of tumor types and grades.
• Grade I: well-differentiated.
• Grade II: moderately differentiated.
• Grade III: moderately undifferentiated/anaplastic.
• Grade IV: poorly differentiated/undifferentiated/highly anaplastic.

Staging of Tumors

• Staging: determining how far the cancer has spread in the body.
• TNM staging: assessing the primary tumor size (T), regional lymph node involvement (N), and distant metastasis (M).
• AJC staging: A separate staging system to assess the cancers' stage.

Tumor Angiogenesis

• Angiogenesis is the formation of new blood vessels.
• Solid tumors need angiogenesis to get larger than a few millimeters.
• Tumor cells require a blood supply for growth and metastasis.

Mechanisms of Invasion and Metastasis

• Invasion and metastasis are key characteristics of malignant tumors.
• Loss of adherence: detachment of tumor cells from each other.
• Invasion of extracellular matrix (ECM): tumor cells invade surrounding tissue.
• Migration of tumor cells through ECM: cytokines promote migration.
• Vascular dissemination and homing: spread through circulatory system.