Final answer:
The notation indicating no known distant metastases in cancer staging is M0, with M signifying metastasis and the number 0 indicating no distant spread has been detected.
Step-by-step explanation:
The notation that means there are no known distant metastases in the context of cancer staging is M0. In medical notation for cancer staging, M stands for metastasis, and the number 0 following the M indicates that no distant spread of cancer has been found. For instance, in the TNM staging system, which is a common system used for describing the extent of cancer spread, T refers to the size and extent of the main tumor, N refers to the spread to nearby lymph nodes, and M indicates whether distant metastasis is present or absent. M0 would indicate that there is no evidence of distant metastases, while M1 would indicate that there are distant metastases.