18 years of age or older

Diagnosis of soft tissue sarcoma and breast cancer patients scheduled for a lumpectomy or mastectomy.

Subjects must be scheduled for surgical resection of a tumor at least 1 cm in size.

Performance status of 0 or 1

Able to read, understand and sign an informed consent form

Must be able and willing to follow study procedures and instructions including a possible overnight stay before surgery

Otherwise healthy except for the diagnosis of cancer

ALT, AST, and total bilirubin within 1.5x institutional upper normal limits; and alkaline phosphatase within 2.5x institutional upper normal limits

Serum creatinine of 1.5 mg or less; creatinine clearance greater than 30 ml/min

May have previously received pre-operative external beam radiation therapy for this sarcoma

Cathepsin Activatable Fluorescent Probe