Physiology 364 Cancer: Lecture 1 PDF

Physiology 364 Cancer: Lecture 1 Prof A-M Engelbrecht [email protected] Mike de Vries Building, Room 2050  What is cancer? Definitions: – Neoplasm: new growth – Malignant neoplasm: uncontrolled growth (division beyond normal limits),...

Physiology 364 Cancer: Lecture 1 Prof A-M Engelbrecht [email protected] Mike de Vries Building, Room 2050  What is cancer? Definitions: – Neoplasm: new growth – Malignant neoplasm: uncontrolled growth (division beyond normal limits), invasion (intrusion on and destruction of adjacent tissues), and metastasis (spread to other locations in the body via blood or lymph). – Benign neoplasm: self-limited, do not invade and do not metastasize ONCOLOGY: Branch of medicine concerned with the study, diagnosis, treatment and prevention of cancer.  Cancer cells invade Blood surrounding tissue and vessel vessels Cancer cells are transported by the circulatory system to distant sites Cancer cells reinvade and grow at a new location  Aetiology For most patients the cause of illness (disease) is unknown, however, several factors have been identified as being associated with the development of the malignancy: – Cigarette tobacco – Alcohol – Diet – Exposure to ultraviolet light – Infectious agents – Drugs Oestrogens – breast, vaginal and endometrial carcinomas  Causative factors associated with the development of cancer Smokingmouth, pharynx, oesophagus, lung, bladder lip Ultraviolet light skin, lip Alcohol mouth, pharynx, larynx, oesophagus, colorectal Drugs bladder, bone marrow Asbestos lung, mesothelium Oestrogens breast, endometrium, vagina Vinyl chloride liver (angiosarcoma) Polycyclic hydrocarbons skin, lung Aromatic amines bladder Aflatoxin liver  Biological agents: A. Hepatitis B virus liver B. Schistosoma japonicum (paracite) gut, bladder C. Helicobacter pylori (gram-negative bacterium) stomach D. Human papilloma virus (HPV ) – Gardasil vaccine cervical cancer Gram-negative bacteria Parasite enters the body and begin to produce eggs, it uses the hosts' immune system (granulomas) for transportation of eggs into the gut Infection preventable by vaccination Hepatitis B virus DNA viruses  Epidemiology The study of the incidence and distribution of the disease Projected at 17 million deaths in 2030 Account for 13% of all deaths worldwide Cancer is responsible for 1 in 8 deaths worldwide Cancer causes more deaths than AIDS, tuberculosis, and malaria combined – Geographical distribution – Age distribution  Oncology-related terms (1) Tumour: solid neoplasm (neoplasms such as leukemia do not form tumours) Pre-malignancy, pre-cancer or non-invasive tumour: A neoplasm that is not invasive but has the potential to progress to cancer (become invasive) if left untreated. These lesions are, in order of increasing potential for cancer, atypia, dysplasia and carcinoma in situ (stage 0, non- invasive). LSIL – Low Grade Squamous Intraepithelial Lesions CIN – Cervical Intraepithelial Neoplasia Atypical columnar epithelial cells  Oncology-related terms (2) Screening: a test done in healthy people to detect tumours before they become apparent. A mammogram is a screening test. Diagnosis: the confirmation of the cancerous nature of a lump. This usually requires a biopsy or removal of the tumour by surgery, followed by examination by a pathologist. Surgical excision: the removal of the tumour by a surgeon Recurrence: a new tumour that appear at the site of the original tumour after surgery.  Surgical margins the evaluation by a pathologist of the edges of the tissue removed by the surgeon to determine if the tumour was completely removed (negative margins) or if tumour was left behind (positive margins)  Grade A number (usually on a scale of 3) established by a pathologist to describe the degree of resemblance of the tumour to the surrounding benign tissue. Grading systems: Bethesda Gleeson, etc  Grading of cervical intraepithelial neoplasia  Stage A number (usually on a scale of 4) established by the oncologist to describe the degree of invasion of the body by the tumour.  Oncology-related terms (3) Metastasis: new tumours that appear far from the original tumour Transformation: low-grade tumour can transform to a high-grade tumour over time Chemotherapy: treatment with drugs Radiation therapy: treatment with radiation Immunotherapy: Cancer Prac Prognosis: the probability of cure after the therapy. It is usually expressed as a probability of survival five years after diagnosis or it can be expressed as the number of years when 50% of the patients are still alive.  Modes of chemotherapy…the basics Primary chemotherapy Used as the sole anti-cancer treatment in highly sensitive tumour types. Concurrent chemotherapy Given simultaneous to radiation to increase the sensitivity of cancer cells to radiation. Adjuvant chemotherapy Given after surgical removal of tumour to “mop-up” microscopic residual disease in the knowledge that widespread microscopic dissemination occurred. Neoadjuvant chemotherapy Given before surgical removal of tumour to shrink the tumour to increase the chance of successful resection.  Classification (1) Carcinoma: Malignant tumours derived from epithelial cells. Represents the most common cancers, including the common forms of breast, prostate, lung, cervical and colon cancer. Sarcoma: A cancer that arises from transformed cells of mesenchymal origin. Thus, malignant tumors made of cancerous bone, cartilage, fat, muscle, vascular, or hematopoietic tissues are, by definition, considered sarcomas. Lymphoma and leukemia: malignancies derived from hematopoietic (blood-forming) cells Germ cell tumour: Tumours derived from totipotent cells. In adults most often found in testicles and ovaria; in fetuses, babies and young children most often found in the body midline. Blastoma (blastic tumour): A tumour (usually malignant) which resembles immature or embryonic tissue. Many of these tumours are most common in children. Human development begins when a sperm fertilizes an egg and creates a single totipotent cell. In the first hours after fertilization, this cell divides into identical totipotent cells. Approximately four days after fertilization and after several cycles of cell division, these totipotent cells begin to specialize. Totipotent cells have total potential. They specialize into pluripotent cells that can give rise to most, but not all, of the tissues necessary for fetal development. Pluripotent cells undergo further specialization into multipotent cells that are committed to give rise to cells that have a particular function. For example, multipotent blood stem cells give rise to the red cells, white cells and platelets in the blood.  Classification (2) Malignant tumours: usually named using –carcinoma, -sarcoma or –blastoma as a suffix, with the Latin or Greek word for the organ of origin as the root. Eg. Cancer of: liver – hepatocarcinoma; cancer of fat cells - liposarcoma  Classification (3) Epithelia Carcinoma – cancer of epithelial origin Adenocarcinoma – cancer of glandular epithelium Angiosarcoma – cancer of endothelial cells (inner surface of heart and all blood vessels) Mesothelioma – cancers of mesothelium lining the ventral cavities of the body Connective tissue Fibromas – benign tumours of fibroblast origin Lipomas – benign tumours of adipose tissue Liposarcomas – cancer of adipose tissue Leukemias – cancers of blood-forming tissues Lymphomas – cancers of lymphoid tissues Chondromas – benign tumours in cartilage Chondrosarcomas – cancer of cartilage Osteomas – benign tumours of bone Osteosarcomas – cancer of bone  Classification (4) Muscle tissue Myomas – benign muscle tumours Myosarcomas – cancer of skeletal muscle tissue Cardiac sarcomas – cancer of cardiac muscle tissue Leiomyomas – benign tumours of smooth muscle Leiomyosarcomas – cancer of smooth muscle tissue Neural tissues Gliomas – cancer of neuroglial origin Neuromas – cancer of neuronal origin