In the context of colorectal surgery, what is the key indicator that systemic therapy is appropriate based on pathology?

In colorectal surgery, the presence of lymph node involvement is a critical indicator for determining the appropriateness of systemic therapy. When the pathology report reveals that cancer has spread to the lymph nodes, it indicates that the cancer has potentially progressed beyond the primary tumor site. This finding is significant because it can suggest a higher risk of metastasis, which is when cancer spreads to other parts of the body.

In such cases, systemic therapy—like chemotherapy—may be recommended to help eradicate undetected cancer cells and reduce the risk of recurrent disease. The decision to initiate systemic therapy hinges on this involvement, as it signals that the disease is more advanced and warrants aggressive treatment to improve overall patient outcomes.

The other options, while relevant to the overall picture of the disease, do not serve as strong indicators for systemic therapy. For example, tumor size can play a role in staging but does not directly correlate with the need for systemic treatment. The location of the tumor might affect surgical decisions but is less influential in determining the need for adjunct systemic therapy compared to lymph node status. Patient age is considered in treatment plans but is not a direct indicator of the cancer's spread or the appropriateness of systemic therapy.