What is the Difference Between Isolated Tumor Cells and Micrometastases?

Isolated tumor cells (ITC) and micrometastases (MM) are both small tumor deposits found in regional lymph nodes, but they differ in size and clinical significance. The American Joint Committee on Cancer defines ITC as tumor cell clusters that are ≤0.2 mm in diameter (denoted as pN0 [i+]), while micrometastases are defined as those that are >0.2 mm in diameter but ≤2 mm (denoted as pN1mi).

The main differences between isolated tumor cells and micrometastases are:

1. Size: Isolated tumor cells are smaller than micrometastases, with a diameter of ≤0.2 mm, while micrometastases have a diameter between 0.2 mm and 2 mm.
2. Clinical Significance: The presence of ITC or MM is not always considered an adverse prognostic factor in certain types of cancer, such as endometrial cancer. However, the presence of ITC/MM can be an independent risk factor for extrapelvic recurrence in some cases. On the other hand, the distinction between ITC and MM in breast cancer may have an impact on the outcome of the disease.

In routine practice, the distinction between isolated tumor cells and micrometastases can be challenging, and the reliability and usefulness of this distinction may vary depending on the type of cancer and the specific clinical context.

Comparative Table: Isolated Tumor Cells vs Micrometastases

The difference between isolated tumor cells (ITC) and micrometastases (MIC) lies in their definition, size, and clinical significance. Here is a table summarizing the differences:

In summary, isolated tumor cells are single tumor cells found in regional lymph nodes or bloodstream, while micrometastases are small tumor deposits in regional lymph nodes with a specific size range. The clinical significance of these entities varies depending on the type of cancer and the specific context.