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
Definitions
Benign Tumors
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Small
Slow-growing
Non-invasive
Well-differentiated
Stay localized
• Stay where they are.
• Can’t invade or
metastasize.
Malignant Tumors
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Large
Fast-growing
Invasive
Poorly-differentiated
Metastasize
• Infiltrate, invade, destroy
surrounding tissue.
• Then metastasize to other
parts of body.
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
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 welldifferentiated ones.
• Growth is dependent on:
1. Blood supply
2. Hormonal factors
3. Emergence of aggressive sub-clones
Carcinoma in situ
Invasive carcinoma
Invasive carcinoma
Metastasizing 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
Metastasis
Three ways tumors metastasize
1. Seeding
2. Lymphatic spread
3. Hematogenous spread
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
• 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
1. Chemicals
2. Radiation
3. Bugs/viruses
Carcinogenic Agents
1- Chemicals
• 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)
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
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HTLV-1: T-cell lymphoma
Human papilloma virus: Cervical cancer
Epstein Bar virus: various lymphomas
Hepatitis B and C: hepatocellular carcinoma