Final answer:
During pregnancy, breast cancer can spread to the regional lymph nodes, which are more likely to contain tumor cells.
Step-by-step explanation:
When breast cancer is diagnosed during pregnancy, regional LN are more likely to contain tumor cells. Pregnancy hormones can stimulate the growth and spread of cancer cells in the lymph nodes near the breast. This is why it is important for pregnant women to receive prompt medical evaluation and treatment if breast cancer is detected.