Observational (ultrasound)

AIM 1: Participants undergo a breast ultrasound over 15 minutes.~AIM 2: Participants undergo breast ultrasounds over 15 minutes before starting the chemotherapy and/or endocrine therapy, 2 months after start of chemotherapy and/or endocrine therapy, and after the completion of chemotherapy and/or endocrine therapy before surgery. Participants may also undergo breast ultrasounds at 2 weeks after start of chemotherapy and/or endocrine therapy and 1 month after start of chemotherapy and/or endocrine therapy.~AIM 3: Patients with suspicious breast masses or known breast cancer who are scheduled for axillary lymph node biopsy undergo ultrasound over 15 minutes at the same visit of the breast mass study.