Chapter 6 Cancer

Frequency and Significance Cancer is the 2 nd 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