Chapter 12: Cancer Biology

Which statement characterizes radiation therapy? (a) Radiation is used to kill cancer cells while minimizing damage to normal structures. (b) Effective killing of cancer cells using radiation requires poor local delivery of oxygen. (c) Radiation blocks the normal growth pathways in cells. (d) Radiation can cause reversible changes in normal tissues.

(a) Radiation is used to kill cancer cells while minimizing damage to normal structures. Radiation is used to kill cancer cells while minimizing damage to normal structures. Effective cell killing using radiation also requires good local delivery of oxygen. Radiation produces slow changes in most cancers and irreversible changes in normal tissues as well. Antimetabolite chemotherapy blocks normal growth pathways in cells.

When in its normal state, which gene negatively regulates proliferation? (a) Oncogenes (b) Tumor-suppressor genes (c) Proto-oncogenes (d) Telomeres

(a) Tumor-Suppressor Genes Tumor-suppressor genes encode proteins that, when in their normal state, negatively regulate proliferation. Oncogenes are mutant genes that, when in their normal nonmutant state, direct the synthesis of protein that positively accelerate proliferation. A proto-oncogene is an oncogene in its nonmutant state. Telemeres are protective ends or caps on each chromosome.

Which statement regarding tumors is true? (a) All neoplasms are cancerous. (b) Cancer refers to a malignant tumor. (c) Benign growths are cancerous. (d) Malignant tumors have slow growth.

(b) Cancer refers to a malignant tumor. The term cancer refers to a malignant tumor with rapid growth, a loss of differentiation, and the absence of normal tissue organization. Neoplasm generally refers to new growth and may be benign or cancerous. Benign growths, which are not referred to as cancers, may retain some normal tissue structure and do not invade the capsules surrounding them or spread to regional lymph nodes or distant locations.

Which statement is true regarding metastasis? (a) Metastasis is a highly efficient process. (b) Metastasis occurs through the vascular and lymphatic systems. (c) Metastatic cancer cells suppress proteases. (d) Most cancer cells are able to metastasize to new areas.

(b) Metastasis occurs through the vascular and lymphatic systems. Two distinct mechanisms give rise to patterns of distant spread. First, cancer cells spread through vascular and lymphatic pathways, as well as natural tissue planes. Metastatic cells are very heterogeneous, and some of these cells have new abilities that can facilitate metastasis. Metastasis is highly inefficient; to metastasize, a cancer cell must surmount multiple physical and physiologic barriers. Many metastatic cells secrete proteases and protease activators to digest the extracellular matrix and basement membrane, enabling cells to move. Only rare cells in a cancer are able to metastasize.

Which statement is true regarding the staging of cancer? (a) Localized cancer is considered a high stage. (b) Benign tumors are stage 4. (c) Cancers that have spread regionally are stage 3. (d) Stage 1 has the poorest prognosis.

(c) Cancers that have spread regionally are stage 3. Cancer confined to the organ of origin is stage 1; cancer that is locally invasive is stage 2; cancer that has spread to regional structures, such as lymph nodes, is stage 3; and cancer that has spread to distant sites, such as a liver cancer spreading to the lung or prostate cancer spreading to bone, is stage 4. The prognosis generally worsens with increasing tumor size, lymph node involvement, and metastasis. Benign tumors do not spread to distant regions.

Which marker is used to evaluate a tumor of the adrenal gland? (a) Prostate-specific antigen (PSA) (b) Alpha-fetoprotein (AFP) (c) Catecholamines (d) Adrenocorticotropic hormone (ACTH)

(c) Catecholamines Catecholamines are secreted by the adrenal medulla and are found in excess if a tumor exists. PSA levels are used to detect prostate cancer. AFP is used to detect liver and germ cell cancers. ACTH is the marker used to detect pituitary adenomas.

Which is a characteristic of a malignant tumor? (a) It is encapsulated. (b) It does not invade local tissues. (c) It is well differentiated. (d) It is able to spread far from the tissue of origin.

(d) It is able to spread far from the tissue of origin. Malignant tumors have no capsule, which allows them to spread readily. They have rapid growth rates and specific microscopic alterations. They are poorly differentiated and spread to distant tissues.

What is the term for cancers originating in connective tissue? (a) Sarcoma (b) Leukemia (c) Lymphoma (d) Carcinoma

(d) Sarcoma Cancers arising from connective tissue usually have the suffix sarcoma. Cancers of lymphatic tissue are called lymphomas, whereas cancers of blood-forming cells are called leukemias. Carcinoma is a cancer of epithelial tissue.

Which statement is true regarding caretaker genes? (Select all that apply.) O Caretaker genes encode proteins that repair damaged deoxyribonucleic acid (DNA). O Loss of function results in increased mutation rates. O Loss of function can cause increased rates of cancer. O Mutations that disrupt caretaker genes are not inherited. O Loss of function causes chromosome instability.

O Caretaker genes encode proteins that repair damaged deoxyribonucleic acid (DNA). O Loss of function results in increased mutation rates. O Loss of function can cause increased rates of cancer. Caretaker genes are repair mechanisms responsible for maintenance of the genetic code. Loss of function of caretaker genes leads to increased overall mutation rates and is responsible for the increase in rates of cancer. Inherited mutations can disrupt the caretaker genes that protect the integrity of the genome. The underlying mechanism of chromosome instability is not clear but may be caused by malfunctions in the cellular machinery that regulates chromosome segregation at mitosis.

Which are characteristics of cachexia? (Select all that apply.) O Increased Appetite O Weight Gain O Early Satiety O Altered Metabolism

O Early Satiety O Altered Metabolism Cachexia includes anorexia, early satiety, weight loss, anemia, asthenia, taste alterations, and altered metabolism. Clinical manifestations of cancer include cachexia.

Which virus is linked to the development of cancer? (Select all that apply.) O Hepatitis A O Hepatitis B O Hepatitis C O Epstein-Bar Virus O Human Papillomavirus

O Hepatitis B O Hepatitis C O Epstein-Bar Virus O Human Papillomavirus Hepatitis B and C have been linked to the development of liver cancer, which is usually caused by chronic inflammation. Epstein-Barr virus can lead to B-cell lymphomas in those individuals who are immunosuppressed. Human papillomavirus has been linked to cervical, anogenital, oral-pharyngeal, and penile cancers. Hepatitis A has not been linked to the development of cancer.