In the second half of the 19th century, most cancer patients were cared for by surgeons who exerted ascesis and limited their operations to 1 or 2 specific areas. To assist surgeons and other physicians in caring for their patients, pathologists described newly discovered entities, refined the microscopic classification of tumors, and introduced the grading of cancers. The discoveries of Rontgen and the Curies revolutionized the diagnosis and treatment of cancers. The search for the cause of cancers extended to infectious organisms, chemicals, and radioactive materials. The 50 years covered in this review formed the groundwork for the coordinated, specialized care of cancer patients at institutions dedicated to render the most promising treatment. Cancer 2012. © 2012 American Cancer Society.