TUMORS and NEOPLASM

Neoplasia and Neoplasm Neoplasm is an abnormal mass of tissue as a result of neoplasia Neoplasia (new growth in Greek) is the abnormal proliferation of cells.

Definitions Neoplasm is mass of tissue that grows excessively, and keeps growing even if you remove the stimulus that started it off Types: Benign tumor and Malignant tumor

Benign Tumors Malignant Tumors Definitions Large Small Fast-growing Invasive Poorly-differentiated Metastasize Infiltrate, invade, destroy surrounding tissue. Then metastasize to other parts of body. Small Slow-growing Non-invasive Well-differentiated Stay localized Stay where they are. Can’t invade or metastasize.

Benign versus Malignant

1- Benign Tumors Usually designated by adding “-oma” to cell type Adenoma – benign tumor arising from glandular cells Leiomyoma – benign tumor arising from smooth muscle cells Chondroma – benign tumor arising from chondrocytes Other benign tumor names Papilloma – has finger-like projections Cystadenoma – has hollow spaces (cysts) inside

A- Carcinomas – arise in epithelial tissue 2- Malignant Tumors A- Carcinomas – arise in epithelial tissue Adenocarcinoma – malignant tumor of glandular cells Squamous cell carcinoma – malignant tumor of squamous cells B- Sarcomas – arise in mesenchymal tissue Chondrosarcoma – malignant tumor of chondrocytes Angiosarcoma – malignant tumor of blood vessels Rhabdomyosarcoma – malignant tumor of skeletal muscle cells Mesenchymal tissue are capable of developing into connective tissue, bone, cartilage, the lymphatic system, and the circulatory system

Tumor Characteristics Differentiation and Anaplasia Differentiation is how much the tumor cells resemble their cells of origin. well-differentiated – closely resembles moderately-differentiated – sort of resembles poorly-differentiated – doesn’t resemble Benign tumors are usually well-differentiated Malignant tumors can’t show any level of differentiation.

Rate of Growth Generalizations Malignant tumors grow faster than benign ones. Poorly-differentiated tumors grow faster than well-differentiated ones. Growth is dependent on: Blood supply Hormonal factors Emergence of aggressive sub-clones

Metastasizing carcinoma Carcinoma in situ Invasive carcinoma Metastasizing carcinoma Invasive carcinoma

Metastasis Metastasis is development of secondary tumor in distant tissues Half of all patients with malignancies have meets at the time of diagnosis!! Metastasis depends on: Type of tumor Size of tumor Degree of differentiation of tumor

Three ways tumors metastasize Metastasis Three ways tumors metastasize Seeding Lymphatic spread Hematogenous spread

Three ways tumors metastasize Metastasis Three ways tumors metastasize 1. Seeding Tumor invades body cavity Bits break off and implant on peritoneal surfaces Ovarian cancer 2. Lymphatic spread Tumor spreads to local lymph nodes Sentinel lymph node first Moves through thoracic duct Empties into subclavian vein Carcinomas of the breast

Metastasis 3. Hematogenous spread Veins are easier to invade than arteries Liver and lungs are most common metastatic destinations eg. Sarcomas

Cancer Incidence Decrease in death rates for Most common cancers Men: Prostate Women: Breast Deadliest cancers Men: Lung Women: Lung Decrease in death rates for Colon cancer (earlier detection) Breast cancer (earlier detection) Lung cancer in men (less smokers) Some types of leukemia (new treatment) Increase in death rates for: Lung cancer in women (more smokers)

Carcinogenic Agents Chemicals Radiation Bugs/viruses

1- Chemicals Carcinogenic Agents Direct-acting agents Indirect-acting agents Require conversion to become carcinogenic Examples: hydrocarbons (in tobacco, charred meats) aflatoxin B (from Aspergillus-infected grains, nuts) nitrites (food preservative)

Causes chromosome breakage, translocations Carcinogenic Agents 2- Radiation Ionizing radiation Causes chromosome breakage, translocations Examples: Unprotected miners: lung cancer Atomic bomb survivors: leukemia, other cancers Therapeutic head/neck radiation: thyroid cancer

Carcinogenic Agents 3- Bugs HTLV-1: T-cell lymphoma Human papilloma virus: Cervical cancer Epstein Bar virus: various lymphomas Hepatitis B and C: hepatocellular carcinoma