Neovascularization
Link to PubMed Peer-Reviewed Articles
PDT and SPDT both induces three primary effects following treatment in cancer patients. In addition to causing tumor cell damage often an immune response if observed. Additionally, because tumors often stimulate the growth of new vessels (neovascularization) the abnormal new vessels also selectively absorb the sensitizers and following treatment a coagulation and clotting occurs in the 'feeder' vessels. This can be observed commonly follow the treatment of superficial tumors by a dusky dark color showing thrombosis (clotting) of the vessels in and around the tumor.
Lt Breast before PDT
Lt Breast 4 days after PDT with vessel shutdown and purplish discoloration typically observer
The concept of new vessels 'feeding' a tumor was pioneered by Dr. Folkman many years ago. Every cell needs oxygen to grow, including cancer cells. Since oxygen in the body comes from blood, fast-growing tumors couldn't develop without access to blood vessels.
Folkman later figured out that tumors actually recruited new blood vessels by sending out a protein signal. If you could turn off that growth signal, he reasoned, you could starve the tumors and keep them tiny. The surgeon submitted a paper on his experiments to various medical journals, but the article was rejected time and again. That is, until an editor at the New England Journal of Medicine heard Folkman give a lecture and offered to publish it in the Journal's Beth Israel Hospital Seminars in 1971--ironically, the year the War on Cancer began.
Anti-angiogenesis drugs are useful but have their drawbacks because the drugs designed to choke the tumor's blood supply often take a far longer time to work than traditional toxic chemo--time that people with advanced disease and fast-growing cancers may not have.
SPDT can be observing having the neovascular 'shut-down' effect even as the treatment is progressing and this is another major benefit of the SPDT therapy.