Patho ch 3 (Cell Proliferation + Cancer

Tumor

Abnormal tissue growth, can be benign or malignant

Neoplasia

“New growth”; uncontrolled cell proliferation

Cancer

Malignant tumor; can invade and metastasize

Benign tumor

Non-cancerous growth; localized, slow-growing, well-differentiated, encapsulated

Malignant tumor

Cancerous growth; invasive, fast-growing, poorly differentiated, can metastasize

Carcinoma

Malignant tumor of epithelial tissue

Adenocarcinoma

Malignant tumor of glandular epithelium

Sarcoma

Malignant tumor of connective tissue

Lymphoma

Malignant tumor of lymphatic tissue

Leukemia

Malignancy of blood-forming cells

Glioma

Tumor of glial cells in CNS

Oncology

Study of tumors/cancer

Anaplasia

Loss of cell differentiation; hallmark of malignancy

Metaplasia

Reversible replacement of one mature cell type by another

Dysplasia

Abnormal cell growth, variable size/shape; may be precancerous

Carcinogenesis

Process of cancer development

Initiation

DNA damage or mutation in normal cell

Promotion

Proliferation of mutated cells

Progression

Further mutations → invasive and metastatic capability

Proto-oncogenes

Normal genes promoting cell growth and division

Oncogenes

Mutated proto-oncogenes causing uncontrolled growth

Tumor suppressor genes

Genes that normally inhibit cell division/repair DNA (e.g., TP53, RB)

TP53 gene

Codes for p53 protein; halts cell cycle for DNA repair or triggers apoptosis; mutated in many cancers

RB gene

Retinoblastoma tumor suppressor gene controlling cell cycle

Caretaker genes

Maintain genome integrity by repairing DNA damage

Hallmarks of cancer

Sustained proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis, activating invasion/metastasis, reprogramming energy metabolism, evading immune destruction

Telomerase

Enzyme that maintains telomere length; active in cancer cells → immortality

Angiogenesis

Formation of new blood vessels; cancer uses VEGF to supply tumor

Apoptosis evasion

Cancer cells disable apoptosis pathways

Metastasis

Spread of cancer cells to distant sites via lymphatics, blood, or direct seeding

Steps of metastasis

Local invasion → intravasation → survival in circulation → extravasation → colonization in new tissue

Common metastatic sites

Bone, lung, liver, brain

Sentinel lymph node

First lymph node draining primary tumor; biopsy used for staging

Grading of tumors

Microscopic assessment of differentiation and mitotic activity (Grade 1 = well-differentiated, Grade 4 = poorly differentiated)

Staging of tumors

Clinical/pathologic assessment of size, lymph node involvement, metastasis (TNM system)

TNM system

T = tumor size/invasion, N = lymph nodes, M = metastasis

Paraneoplastic syndromes

Symptoms caused by tumor-produced hormones/cytokines, not direct invasion (e.g., hypercalcemia, Cushing syndrome)

Cachexia

Cancer-related wasting syndrome; weight loss, muscle loss, anorexia, anemia

Cancer risk factors

Age, family history, smoking, alcohol, diet, obesity, infections, occupational exposures, radiation

Carcinogens

Substances causing cancer (chemicals, radiation, viruses)

Chemical carcinogens

Tobacco smoke, asbestos, aflatoxin, nitrosamines

Radiation carcinogenesis

UV light → skin cancer; ionizing radiation → leukemia, thyroid cancer

Oncogenic viruses

HPV (cervical), EBV (Burkitt lymphoma), HBV/HCV (liver), HTLV-1 (T-cell leukemia)

Chronic inflammation and cancer

Persistent inflammation → increased cytokines, ROS, DNA damage (e.g., ulcerative colitis → colorectal cancer)

Cancer epidemiology

Study of cancer patterns, causes, control in populations

Screening tests

Pap smear (cervical), mammogram (breast), colonoscopy (colorectal), PSA (prostate), LDCT (lung in smokers)

Biopsy

Gold standard for cancer diagnosis; tissue examined microscopically

Tumor markers

Substances in blood/urine/tissues indicating cancer (e.g., PSA, CA-125, AFP, CEA)

Cancer treatment

Surgery, radiation, chemotherapy, targeted therapy, immunotherapy

Surgery

Removes localized tumors; may be curative or palliative

Radiation therapy

Damages DNA of cancer cells; localized treatment

Chemotherapy

Systemic drugs killing rapidly dividing cells; affects normal fast-dividing cells too

Targeted therapy

Drugs targeting specific molecules in cancer (e.g., tyrosine kinase inhibitors)

Immunotherapy

Boosts immune system to fight cancer (e.g., checkpoint inhibitors, CAR-T cells)

Side effects of cancer therapy

Fatigue, nausea, hair loss, immunosuppression, anemia, mucositis, infertility

Palliative care

Relieves symptoms, improves quality of life; not focused on cure