Five-year survival rates in excess of 20% may be expected following resection of pulmonary metastases if
**Core Concept**
The five-year survival rate for patients undergoing resection of pulmonary metastases is influenced by the primary tumor's location, histology, and the patient's overall health status. The presence of a solitary pulmonary metastasis and a well-differentiated primary tumor often correlates with a favorable prognosis.
**Why the Correct Answer is Right**
The correct answer is related to the principle that patients with a solitary pulmonary metastasis (SPM) and a well-differentiated primary tumor have a better prognosis. This is because SPMs are often amenable to complete resection, which can lead to a significant improvement in survival rates. In contrast, multiple pulmonary metastases and poorly differentiated primary tumors are associated with a poorer prognosis. The 5-year survival rate in excess of 20% may be expected in patients with a solitary pulmonary metastasis from a well-differentiated primary tumor, such as colorectal cancer.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the primary tumor's histology and the number of pulmonary metastases are more significant prognostic factors than the patient's age. While age can influence the patient's overall health status and surgical risk, it is not the primary determinant of survival rates in this context.
**Option B:** This option is incorrect because the presence of lymph node metastases in the primary tumor site is a poor prognostic factor. Patients with lymph node involvement often have a more advanced stage of disease and a poorer survival rate.
**Option C:** This option is incorrect because the primary tumor's location is not the primary determinant of survival rates in patients undergoing resection of pulmonary metastases. While some primary tumor sites may be associated with a better prognosis, the presence of a solitary pulmonary metastasis from a well-differentiated primary tumor is a more significant prognostic factor.
**Option D:** This option is incorrect because the patient's overall health status and performance status are important prognostic factors, but they are not the primary determinant of survival rates in patients undergoing resection of pulmonary metastases.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the presence of a solitary pulmonary metastasis from a well-differentiated primary tumor is a favorable prognostic factor, and patients with this characteristic may expect a 5-year survival rate in excess of 20% following resection.
**Correct Answer: C. A solitary pulmonary metastasis from a well-differentiated primary tumor.**