Chapter 6
Cancer
Frequency and Significance
• Cancer is the 2nd leading cause of death in the
United States
• Obviously, the term cancer covers many types
of malignant neoplasms
• The treatment and outcome for these various
neoplasms is widely different
Frequency and Significance
• The prognosis of cancer depends on several
items:
– The type of cancer
– The extent of spread at the time of
discovery
– The efficacy of existing therapy
• The incidence of malignant tumors is twice
the mortality rate.
Common Cancers
• The most common cancers are basal and
squamous skin cell carcinomas of the skin.
– These account for 99% of all skin cancers
– However, they are rarely fatal
• Malignant melanoma accounts for 1% of skin
cancers, but is fatal in about 20% of patients!
– This discusses the “type” variable of
prognosis
Common Cancers
• The “treatment” variable of prognosis is
readily evident when discussing colon and
lung cancer
• Colon cancer is cured in 50% of patients by
surgical removal
• Lung cancer treatment on the other hand, is
relatively ineffective—a 13% 5 year survival
rate
Etiology
• Cells must undergo an alteration called
initiation to acquire autonomous growth
potential
• Initiation is stimulated by carcinogens which
may be physical, chemical or biologic agents
Etiology
• Promotion is the step after initiation, and is
the selective growth of the initiated cells
• Progression follows, and is the acquisition of
additional DNA mutations
Oncogenes
• Initiators turn oncogenes “on”, which leads to
the proliferation of the cell through growth
enhancing products
• Oncogenes are supposed to be kept in check
by tumor suppressor genes; however, there
can be mutations in the tumor suppressor
genes that prevent them from functioning
properly
Prevention and Cure of Cancer
• While a grand idea, it is an extremely complex
task that depends on the discovery of:
– Oncogenes
– Tumor suppressor genes
– Other target genes
– Initiating agents
Local and Systemic Manifestations
• Unfortunately, many cancers are
asymptomatic until very late in their course
– This can affect treatment options
• Local manifestations relate to symptoms at
the cancer site—pain for example.
Local and Systemic Manifestations
• Systemic manifestations relate to symptoms
not limited to the cancer site—anemia for
example.
Diagnosis
• Diagnosis can be made by a variety of tests
– Biopsy
– Blood smear
– Cytology
– Radiologic Examination
– Endoscopic Examination
TNM System
• T—tumor, the size and invasion into
surrounding tissue
• N—extent of lymph node metastasis
• M—whether distant metastasis has occurred
• Stage I is localized, Stage IV is metastasis
Treatment
• Surgical Removal
• Radiation Therapy
• Chemotherapy