When might a registrar consider using the "Single Tumor" module?

The "Single Tumor" module is appropriate when there is one tumor with separate microscopic foci, which reflects a scenario where multiple tumor foci exist but are part of a single tumor entity. This means that while there may be multiple areas of cancer within the same tumor (for example, multiple microscopic foci within a single site), they are not classified as distinct tumors because they originate from the same primary site and share the same histological characteristics.

This approach helps maintain consistency in tumor reporting and ensures that data can be utilized accurately for treatment and research purposes. Since the focus is on a single tumor rather than multiple distinct tumors, using the "Single Tumor" module in such instances allows for proper classification and improves the quality of the cancer registry data.

In contrast, separate tumors in different sites would not be accurately classified under this module, nor would cases of metastasis or overlapping tumors, as these represent more complex scenarios that typically require different approaches for data entry and classification.