In colorectal cancer staging, what does stage III indicate?

Stage III colorectal cancer is characterized by lymph node involvement, indicating that the cancer has spread beyond the primary tumor but is still contained within the local area. This stage typically means that the cancer has invaded nearby lymph nodes but not yet metastasized to distant organs. The presence of cancerous cells in lymph nodes is a critical factor in staging because it suggests a higher risk of the disease progressing and affects treatment decisions.

In this context, local tumors without spread, as noted in another choice, would correspond to earlier stages of cancer (such as stage I). The option regarding metastasis to other organs describes stage IV disease, highlighting that the cancer has advanced significantly beyond the original site. Similarly, invasion of adjacent organs is indicative of advanced local disease, potentially classified as stage II or stage III depending on lymph node involvement, but does not solely delineate stage III. Therefore, the defining characteristic of stage III is its association with lymph node involvement, making it a crucial aspect in the prognosis and management of colorectal cancer.