NEOPLASIA II - Characteristics of Tumors

By Dr. Eric Po Lasala, DPSP

 

1. Differentiation

 

  • Refers to the parenchymal cells of the neoplasm
  • It is the extent to which parenchymal cells resemble normal cells whether morphologically or functionally
  • May range from well differentiated to undifferentiated
  • Moderately differentiated cells are in between the spectrum

 

2. Anaplasia

 

  • Lack of differentiation
  • This is the hallmark of a malignant transformation
  • Means to “form backwards” ,that is reversion from a higher differentiation to lower
  • Markers of anaplasia:

Ø       Pleomorphism- variation in size and shape of the cell and its nuclei

Ø       Hyperchromatic nuclei

Ø       Reversion of the  nucleo-cytoplasmic ratio

Ø       Presence of a nucleoli

Ø       Formation of giant tumor cells

Ø       Loss of normal polarity

 

3. Dysplasia

 

  • Disordered growth
  • Encountered in the epithelial cells
  • Include any of the following changes:

Ø       Loss of uniformity of individual cells

Ø       Loss of architectural orientation

Ø       Pleomorphism

Ø       Hyperchromatic nuclei

Ø       Reversed nucleo-cytoplasmic ratio

Ø       Abundant mitotic figures

 

4. Rate of Growth

 

  • Most benign tumors grow slowly over a period of years, whereas most cancers grow rapidly sometimes at an erratic phase to eventually spread and kill the host

 

  • Factors That Affect Rate of Growth

Ø       Hormones

Ø       Adequate blood supply

Ø       Degree of differentiation

 

5. Local Invasion

 

  • Nearly all benign tumors grow as a cohesive expansile masses that remain localized to their site of origin and do not have capacity to infiltrate, invade or metastasize to distant sites as do malignant tumors

 

 

6. Metastasis

 

  • Tumor implants that are discontinuous with the primary tumor
  • Unequivocal mark of a malignant tumor
  • All cancers metastasize
  • Nearly 30% of patients diagnosed with solid tumors present with metastasis
  • Pathways of Metastasis

Ø       Direct seeding of body cavities

Ø       Lymphatic spread

Ø       Hematogenous spread

 

Epidemiology of Cancer

 

v      In the US, 546,000 died of cancer in 1998

v      There is an increasing incidence of cancers of the lungs in both sexes

v      Decreasing cancer of cervix in women due to early detection

 

Factors That Affect Incidence of Cancer

 

v      Geographic and environmental factors

v      Age

v      Heredity

v      Biology of Tumor Growth

v      Kinetics of Tumor Cell Growth

v      Growth Functions