Porth's Essentials of Pathophysiology, 4e

155

Neoplasia

C h a p t e r 7

the highest radiation doses are most likely to have subsequent cognitive difficulties. 73–75 Growth hormone deficiency in adults is associated with increased preva- lence of dyslipidemia, insulin resistance, and cardiovas- cular mortality. 77 Moderate doses of cranial radiation therapy (CRT) are also associated with obesity, particu- larly in female patients. For many years, whole-brain radiation or cranial radiation was the primary method of preventing CNS relapse in children with acute lym- phocytic leukemia. Because of cognitive dysfunction associated with CRT, other methods of CNS prophy- laxis are now being used. Delayed sexual maturation in both boys and girls can result from chemotherapy with alkylating agents or from irradiation of the gonads. Cranial irradiation may result in premature menarche in girls, with subsequent early closure of the epiphyses and a reduction in final growth achieved. Data related to fertility and health of the offspring of childhood cancer survivors is just becoming available. Vital organs such as the heart and lungs may be affected by cancer treatment. Children who received anthracyclines (i.e., doxorubicin or daunorubicin) may be at risk for developing cardiomyopathy and conges- tive heart failure. Pulmonary irradiation may cause lung dysfunction and restrictive lung disease. Drugs such as bleomycin, methotrexate, and busulfan also can cause lung disease. ■■ Although most adult cancers are of epithelial cell origin, most childhood cancers involve the hematopoietic system, nervous system, or connective tissue. ■■ Heritable forms of cancer tend to have an earlier age of onset, a higher frequency of multifocal lesions in a single organ, and bilateral involvement of paired organs or multiple primary tumors. ■■ The early diagnosis of childhood cancers often is overlooked because the signs and symptoms mimic those of other childhood diseases. ■■ With improvement in treatment methods, the number of children who survive childhood cancer is continuing to increase. As these children approach adulthood, there is continued concern that the life-saving therapy they received during childhood may produce late effects, such as impaired growth, cognitive dysfunction, hormonal dysfunction, cardiomyopathy, pulmonary fibrosis, and risk for second malignancies. SUMMARY CONCEPTS

R E V I EW E X E R C I S E S 1. A 30-year-old woman has experienced heavy menstrual bleeding and is told she has a uterine tumor called a leiomyoma. She is worried she has cancer. A. What is the difference between a leiomyoma and leiomyosarcoma? B. How would you go about explaining the difference to her? 2. Among the characteristics of cancer cells are the lack of cell differentiation, impaired cell–cell adhesion, and loss of anchorage dependence. A. Explain how each of these characteristics contributes to the usefulness of the Pap smear as a screening test for cervical cancer. 3. A 12-year-old boy is seen in the pediatric cancer clinic with osteosarcoma. His medical history reveals that his father had been successfully treated for retinoblastoma as an infant. A. Relate the genetics of the retinoblastoma (RB) gene and “two hit” hypothesis to the development of osteosarcoma in this boy. 4. A 48-year-old man presents at his health care clinic with complaints of leg weakness. He is a heavy smoker and has had a productive cough for years. Subsequent diagnostic tests reveal he has a small cell lung cancer with brain metastasis. His proposed plan of treatment includes chemotherapy and radiation therapy. A. What is the probable cause of the leg weakness and is it related to the lung cancer? B. Relate this man’s smoking history to the development of lung cancer. C. Explain the mechanism of cancer metastasis. D. Explain the mechanisms whereby chemotherapy and irradiation are able to destroy cancer cells while having less or no effect on normal cells. 5. A 17-year-old girl is seen by a guidance counselor at her high school because of problems in keeping up with assignments in her math and science courses. She tells the counselor that she had leukemia when she was 2 years old and was given radiation treatment to her brain. She confides that she has always had more trouble with learning than her classmates and thinks it might be due to the radiation. She also relates that she is shorter than her classmates and this has been bothering her. A. Explain the relationship between cranial radiation therapy and decreased cognitive function and short stature. B. What other neuroendocrine problems might this girl have as a result of the radiation treatment?