Cancer Biology II: Invasion & Tissue Metastasis and Cancer Epidemiology

Tumor spread

Ways tumors spread: distant (lymph nodes, blood stream), implantation (surgical instrument transfer)

Local spread of cancer

Spreads within primary tumor site and nearby tissues, prerequisite to metastasis

Metastasis

Spread from primary tissues to distant organs, involves lymphatic and blood vessel transport

Staging

Determines spread, size, invasion, and metastasis extent; associated with survival and cure rate statistics

Cancer grade

Assigned by pathologist based on tumor rate of growth and response to chemotherapy

Metastatic process

Cancer cells secrete protease, digest extracellular matrix, survive in new environment, undergo epithelial-mesenchymal transition

Angiogenesis

Development of new blood vessels, crucial for cancerous colony growth

Chemotherapy

Use of nonselective cytotoxic drugs to eliminate tumor cells, causing side effects like oral ulcers, hair loss, and bone marrow suppression

Radiation therapy

Kills cancer cells while minimizing damage to normal structures, side effects include skin breakdown and dryness

Induction chemotherapy

Causes shrinkage or disappearance of tumors

Neoadjuvant therapy

Administered before localized treatment to shrink tumor prior to surgical removal

Adjuvant therapy

Administered after surgical removal of tumor to eliminate micro metastases

Surgery

Definitive treatment for cancers not spreading beyond surgical excision limits

Pain in cancer

Associated with fear, anxiety, sleep loss, fatigue, and physical deterioration

Fatigue in cancer

Most frequently reported symptom, includes tiredness, weakness, lack of energy, and depression

Anemia in cancer

Decrease of hemoglobin in the blood, caused by chronic bleeding, severe malnutrition, medical therapies, or malignancy in blood-forming organs

Leukopenia and thrombocytopenia

Caused by direct tumor invasion to bone marrow or toxicity from chemotherapy drugs

Infection risk in cancer

Increases when absolute neutrophil and lymphocyte counts fall

TNM system

Staging system: T = tumor spread, N = node involvement, M = presence of distant metastasis

Environmental risk factors

Tobacco, alcohol, air pollution, lack of fruit/vegetables, processed/red meat, lack of fiber, hyperglycemia, overweight, lack of exercise, infections, ionizing radiation, occupational hazards, reproduction, sun exposure

Cancers linked to smoking

Lung, mouth, lip, nasal cavity, sinuses, larynx, pharynx, esophagus, pancreas, liver, kidney, uterus, cervix, colon, rectum, acute leukemia

Cancers linked to alcohol

Oral cavity, pharynx, larynx, esophageal, liver, colorectal, breast

Occupational hazards

Asbestos (mesothelioma, lung cancer), ionizing radiation (leukemias, thyroid, breast, lung, stomach, colon, esophageal, urinary tract cancers), sexual reproductive behaviors (cervical, anal, vaginal, vulvar, penile, oropharynx)

Infections linked to cancer

HPV (cervical cancer), Hep B and C (liver cancer), Helicobacter pylori (stomach cancer), Epstein-barr (nasopharynx, stomach, Hodgkin disease, non-hodgkin lymphoma), Human herpes virus type 8 (Kaposi sarcoma), Human T-cell lymphotrophic virus type 1 (leukemia, lymphoma)

Impact of UV light, exercise, obesity, and air pollution on cancer

UV light causes skin cancer, exercise reduces risk for breast, colon, and endometrial cancers, obesity increases risk for 13 cancers, air pollution causes lung cancer