The sodium salt of a mixture of oligomers formed by ether and ester linkages of up to eight porphyrin units with photodynamic activity. Absorbed selectively by tumor cells, porfimer produces oxygen radicals after activation by 630 nm wavelength laser light, resulting in tumor cell cytotoxicity. In addition, tumor cell death may occur due to ischemic necrosis secondary to vascular occlusion that appears to be partly mediated by the release of thromboxane A2. or A drug used to treat some types of cancer. When absorbed by cancer cells and exposed to light, porfimer sodium becomes active and kills the cancer cells. It is a type of photodynamic therapy agent. Also called Photofrin.