Targeting intralymphatic tumor cells in cancer patients. When a patient is diagnosed with cancer, the primary tumor and metastatic lymph nodes are routinely removed in surgery (blue). However, tumor cells (green) in transit in the lymphatic vessels are left behind as a putative source of local tumor relapse, such as in-transit metastasis in melanoma. Photodynamic therapy (PDT) (red) allows for the destruction of tumor-draining lymphatic vessels and the intralymphatic tumor cells. For details on the inset image please see the caption above. This image relates to an article that appeared in the Feb. 9, 2011, issue of Science Translational Medicine, published by AAAS. The study, by Dr. Tuomas Tammela at Institute for Molecular Medicine Finland, in Helsinki, Finland and colleagues, was titled, "Photodynamic Ablation of Lymphatic Vessels and Intralymphatic Cancer Cells Prevents Metastasis."