Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Tumors and Pregnancy ?
    ### Response:
    Tumors during pregnancy are rare, but they can happen. Tumors can be either benign or malignant. Benign tumors aren't cancer. Malignant ones are. The most common cancers in pregnancy are breast cancer, cervical cancer, lymphoma, and melanoma. Cancer itself rarely harms the baby, and some cancer treatments are safe during pregnancy.
    