Chapter 16: Cancer
Cancer encompasses a broad range of diseases of multiple causes that can arise in any cell of
the body capable of evading regulatory controls over proliferation and differentiation.
Two major dysfunctions present in the process of cancer are (1) defective cellular proliferation
(growth) and (2) defective cellular differentiation.
Cancer cells usually proliferate at the same rate of the normal cells of the tissue from which they
arise. However, cancer cells divide indiscriminately and haphazardly and sometimes produce
more than two cells at the time of mitosis.
Protooncogenes are normal cellular genes that are important regulators of normal cellular
processes. When these genes become mutated, they can begin to function as oncogenes
Tumors can be classified as benign or malignant.
o Benign neoplasms are well-differentiated.
o Malignant neoplasms range from well-differentiated to undifferentiated.
The stages of cancer include initiation, promotion, and progression.
o The first stage, initiation, is the occurrence of a mutation in the cell’s genetic structure,
resulting from an inherited mutation, an error that occurs during DNA replication, or
following exposure to a chemical, radiation, or viral agent.
o Promotion, the second stage in the development of cancer, is characterized by the
reversible proliferation of the altered cells.
o Progression, the final stage, is characterized by increased growth rate of the tumor,
increased invasiveness, and spread of the cancer to a distant site (metastasis).
Since cancer cells arise from normal human cells, the immune response mounted against cancer
cells may be inadequate to effectively eradicate them.
The process by which cancer cells evade the immune system is termed immunologic escape.
Tumors can be classified according to anatomic site, histologic (grading), and extent of disease
o In the anatomic classification of tumors, the tumor is identified by the tissue of origin,
the anatomic site, and the behavior of the tumor (i.e., benign or malignant). o In histologic grading of tumors, the appearance of cells and the degree of differentiation
are evaluated pathologically. For many tumor types, four grades are used to evaluate
abnormal cells based on the degree to which the cells resemble the tissue of origin.
o The staging classification system is based on a description of the extent of the disease
rather than on cell appearance.
The biopsy procedure is the only definitive means of diagnosing cancer.
The goal of cancer treatment is cure, control, or palliation.
o When cure is the goal, the treatment offered is expected to have the greatest chance of
disease eradication and may involve local therapy (i.e., surgery or radiation) alone or in
combination with or without periods of adjunctive systemic therapy (i.e.,
o Control is the goal of the treatment plan for many cancers that cannot be completely
eradicated but are responsive to anticancer therapies and, as with other chronic
illnesses such as diabetes mellitus and heart failure, can be managed for long periods of
time with therapy.
o With palliation, relief or control of symptoms and the maintenance of a satisfactory
quality of life are the primary goals rather than cure or control of the disease process.
Modalities for cancer treatment with all three goals include surgery, chemotherapy, radiation