The ancient view regarding
breast cancer as a
metastasis has not been supported so far by experimental evidence. We have implanted
nephroblastoma tumor cells resulting in a rat metastatic kidney
capsule-parathymic lymph node (PTN) model.
India ink implantation confirmed the lymphatic connection between the primary
tumor of the kidney and PTNs. (18)F-FDG
glucose analog distribution provided further evidence that the first metastatic sites of distant
tumor progression are PTNs.
Tumor invasion caused disruptions in the tissue of the primary renal
tumor, releasing
cancer cells into the peritoneal cavity. Colloidal particles, among them bacteria and
India ink, crossed transdiaphragmatic channels drained from the peritonel cavity to the thoracic lymphatics and entered not only in the parathymic lymph nodes but also in the anterior mammary lymph nodes. The kidney
capsule-PTN complex is reflecting a so far unknown mechanism of
tumor development and suggests a similar
tumor progression directed towards mammary lymph nodes. The mammalian
tumor model provides a reasonable explanation for
breast cancer development viewed as a
metastasis, rather than a primary
tumor.