Correct Answer: C

Rationale: Avoiding spicy or acidic foods can help prevent irritation of the mucosa, which is already sensitive during mucositis.

Correct Answer: D

Rationale: Chemotherapy drugs are designed to target and destroy rapidly dividing cells, which include cancer cells. Cancer cells often divide more quickly than normal cells, and chemotherapeutic agents exploit this characteristic to inhibit their growth and promote cell death. While chemotherapy can also affect other rapidly dividing normal cells (such as those in the bone marrow, gastrointestinal tract, and hair follicles), the primary goal is to target cancerous cells.

Correct Answer: C

Rationale: Prophylactic surgery refers to the preventive removal of tissues or organs at high risk for developing cancer, even when no cancer is currently present. In this case, the patient has a positive breast tumor marking test and a significant family history of breast cancer, which places her at increased risk for developing the disease. A bilateral mastectomy is performed to significantly reduce this risk by removing both breasts, thereby preventing the potential future occurrence of breast cancer.

Correct Answer: B

Rationale: In the case of lung cancer that has metastasized to the bones and liver, lymphatic circulation is a key mechanism by which cancer cells spread from the primary tumor site to distant organs. Cancer cells can invade nearby lymphatic vessels and travel through the lymphatic system, eventually reaching lymph nodes and spreading to other tissues and organs. This route is significant in the metastasis of many types of cancer, including lung cancer.

Correct Answer: C

Rationale: Patients preparing for hematopoietic stem cell transplantation (HSCT) undergo intensive chemotherapy and/or radiation, which significantly suppresses their immune system. This immunosuppression leads to a heightened risk for infection, making it the most critical nursing diagnosis for these patients. As the body's ability to fight off pathogens is compromised, close monitoring and interventions aimed at preventing infections are essential for their safety and recovery.