Final answer:
Less than 10% of nipple discharge is associated with underlying malignancy.
Step-by-step explanation:
The best estimate for the percentage of nipple discharge associated with underlying malignancy is less than 10%.
This means that of all cases of nipple discharge, less than 10% are linked to malignancy.
It is important to note that nipple discharge can have various causes, including benign conditions. Therefore, it is always recommended to consult a healthcare professional for an accurate diagnosis.