Second only to etiology, the most important phase of the practical study of tumors is the determination of the anatomic and biologic factors that facilitate or prevent metastases. The cause of cancer is as yet unsolved, but we know that the disease, regardless of its site of origin, ultimately spreads as metastatic growths throughout the body. The metastases may occur late or early, in nearby tissues or in more remote organs, and they are the important determining factor in cancer—usually bringing about the fatal result. Metastases represent cancer cells that have traveled to the point found and are growing as secondary tumors. Whether these detached tumor cells find their way by "spontaneous movements," by "permeation" or by "forcible dissemination," as has been stated by various writers, is of no particular importance.
There are two general routes of tumor cell dissemination, lymphatic and blood. In most instances cancer metastases occur by
NEAL MP, ROBNETT DA. GENERALIZED OSSEOUS METASTASES SECONDARY TO ATROPHIC SCIRRHOUS CARCINOMA OF LEFT BREAST. Arch Surg. 1927;14(2):529-541. doi:10.1001/archsurg.1927.01130140074002