The Basics

An overview of the basics of what you need to know about neoplasia and cancer pathology before you dive into the more detailed sections on specific neoplasia subtypes.

Neoplasia: An abnormal, uncontrolled growth of cells; can be benign or malignant.

What is Neoplasia?

As described above neoplasia is an abnormal and uncontrolled growth of cells. Depending on where it occurs in the body this may appear different but, it will often lead to the formation of a tumour.

Benign tumours are localized and non-invasive (they’re not spreading). Malignant tumours, on the other hand, are invasive and attempt to metastasize (spread throughout the body).

If neoplasia progresses far enough it will become cancer. (1)

(2)

Naming Neoplasia

To the right are some common names you may see when dealing with neoplasia. (1)

Adenoma

benign tumour of gland tissue

Lymphoma

malignant tumor of lymph tissue

Melanoma

malignant tumor of melanocytes (pigment producing cells in epithelium)

Papilloma

benign tumor forming finger-like projections

Carcinoma

malignant tumor of epithelial cells

Sarcoma

malignant tumor of mesenchymal tissue (muscle, bone, fat)

Predisposing Factors Leading to Cancer

Geographic

Some countries have higher rates of certain cancers.

Environmental

Exposure to carcinogens

Age

Due to the accumulation of genetic damage that occurs throughout the life time, most cancers happen in older adults.

Genetics

Accumulation of mutations over time can lead to cancer development

Chemical carcinogens - examples: tobacco smoke, asbestos

Radiation carcinogens - example: UV radiation

Infectious carcinogens - example: HPV

(1)

Tumour suppressor genes

Genes that normally regulate cell growth and proliferation.
Loss of function mutations in these can lead to cancer.

Oncogenes

Genes that normally support cell growth and proliferation.
Gain of function mutations in oncogenes can lead to cancer.

(1)

(3)

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Tumor Grading and Staging

Grading

Refers to the degree of tumor differentiation.

Low Grades
- more differentiated; tumour cells resemble the surrounding tissue
High Grade
- poorly differentiated; tumour does not resemble surrounding tissue and will likely display invasive behaviour into other layers.

(1)

Staging

Refers to the extent of tumor spread based on the TNM system.

T - size and extent of the primary tumour

refers to the origin of the neoplasm

N - Involvement of the regional lymph nodes.

has the tumour spread to lymph nodes nearby?

M - Presence of metastasis

has the tumour spread to other (distant) parts of the body?

(1)

6 Hallmarks of Cancer

These six signs indicate that a neoplasm is cancerous:

Sustaining proliferative signals

(continuously receiving signals to grow and divide)

Evading growth suppressors

Avoiding apoptosis (cell death)

Enabling replicative immortality (able to divide forever without consequence)

Inducing angiogenesis (creating new blood vessels)

Invasive and metastasizing

(1)