Tumor Terminology: Malignant vs. Benign

• Under normal conditions, new cell production is tightly regulated.
• Occasionally, new cells arise that don't respond to normal growth control, leading to the formation of a clone which expands, producing a tumor or neoplasm.
• Tumor immunology terms and definitions are important for the communication between physician and patient.
• Basic terminology describes the interaction between tumor cells, ie, cancer and the host immune defenses.

Key Terminology

Malignant

• Refers to tumor cells that continue to grow and become invasive.
• Malignant tumors arise from cells undergoing uncontrolled and abnormal growth.
• They can infiltrate nearby tissues, disrupting normal organ function, and metastasize to distant sites.
• Clinical manifestations vary depending on the type and location, common signs may include unexplained weight loss, fatigue, pain, and changes in skin appearance.

Benign

• Refers to tumor cells that do not invade healthy surrounding tissue.
• Benign tumors result from abnormal cell growth but lack the ability to invade or spread.
• They grow slowly and maintain a well-defined capsule.
• May cause symptoms depending on size and location, sometimes compressing nearby structures.

Metastasis

• Refers to malignant tumor cells that dislodge from the tumor and invade the blood or lymphatic vessels and are carried into other tissues where they continue to proliferate on the genes.
• Cancer cells break away from the primary tumor, enter the bloodstream or lymphatic system, and establish new tumors in distant organs or tissues.
• Metastasis involves invasion, intravasation, transport, extravasation, and colonization.
• Metastasis can lead to symptoms specific to the affected organs, such as respiratory symptoms for lung metastases or abdominal pain for liver metastases.

Oncogenes

• Refers to cancer-producing genes.
• Oncogenes are genes that, when mutated or activated, promote the development of cancer.
• Mutations in oncogenes can lead to uncontrolled cell proliferation and resistance to normal regulatory signals.
• Specific clinical manifestations depend on the function of the affected oncogene and the type of cancer.

Malignant Transformation

• Refers to the process of change from a normal cell (wild type) to a tumor cell (mutant).

• Malignant transformation involves genetic and epigenetic changes in normal cells, leading to uncontrolled growth and invasion.

• It results from the accumulation of genetic mutations over time.

• Clinical manifestations include the formation of tumors with invasive and metastatic properties, with symptoms varying by affected organ and cancer stage.

• Tumor cells can detach from the primary tumor and travel through the vasculature to establish metastatic tumor growth throughout the body.

• Malignant tumors or cancers are classified according to the embryonic origin of the tissue.

• Over 80% of cancers originate from endodermal or ectodermal tissues like skin or epithelial linings of internal organs and glands.

Leukemia vs Lymphoma

• Leukemias and lymphomas are tumors of the hematopoietic cells of the bone marrow, representing approximately 9% of cancers in the United States.
• Leukemias proliferate as single cells.
• Lymphomas grow as tumor masses.

Sarcomas

• Sarcomas account for about 1% of cancers in the United States and are derived from mesodermal connective tissues like bone, fat, and cartilage.

Video Summary: Cancer Origin

• The body starts as one cell that divides repeatedly to form tissues, organs, and systems.
• Cell division (growth) is intricate, involving individual and community aspects.
• A mutation in a cell's DNA can lead to errors, but most are corrected or eliminated.
• Mutations can bypass safeguards, causing reckless cell division and tumor formation.
• Cancer treatment strategies depend on the cancer's location and progression.
• Surgery may suffice for slow-growing, localized tumors.
• Radiation or surgery followed by radiation may be used for fast-growing, invasive tumors.
• Chemotherapy or combined treatments are typical for widespread or systemic cancers like leukemia.
• Radiation and chemo work by damaging cell DNA or disrupting copying machinery.
• These treatments affect all cells, especially those that divide frequently.
• Side effects of cancer treatment, such as hair loss, skin rashes, nausea, and fatigue, are due to damage to rapidly dividing healthy cells like hair, skin, gut, and blood cells.
• Cancer hijacks cell division machinery, promoting rapid, reckless growth.
• Chemotherapeutic drugs exploit this aggressiveness, targeting the cells dividing at a fast rate.