Final answer:
The cardiovascular system is the least affected by multiple myeloma compared to the skeletal, renal, and nervous systems which are more significantly impacted by the disease.
Step-by-step explanation:
When assessing a patient with multiple myeloma, the body system that is least affected is the D. cardiovascular system. Multiple Myeloma primarily affects the skeletal system, as it is a type of bone marrow cancer that impacts plasma cells and can cause bone damage. It is also known to have significant effects on the renal system due to the high levels of abnormal proteins produced by cancerous cells, which can lead to kidney damage.
The involvement of the nervous system can occur due to the compression of nerves by the growing plasma cells or bone lesions. However, compared to these systems, the cardiovascular system is relatively less impacted in multiple myeloma patients.