The intrinsic fluorescence of synthetic or natural porphyrins is regarded as an attractive
characteristic exploited for assisting early cancer diagnosis and/or tumor localization. Single tumor
cells circulating in the blood stream can be considered a major step in depicting dissemination of primary
tumors, an event of clinical relevance for prognosis, staging or therapy monitoring of cancer.
The third leading cause of cancer death in men is colorectal cancer and the hematogenous spreading of
primary tumor cells is one of the main events in metastasis of this type of cancer. Hidden in the myriad
of circulating blood cells, tumor cells need both a sensitive and affordable detection technique. 5-
(3-methoxy)-4-methoxycarbonylphenyl)-10, 15, 20-tris-(4- methoxycarbonylphenyl) - 21, 23-H porphyne
is a synthetic porphyrin with a noticeable preference of accumulation in peripheral blood mononuclear cells isolated
from cancer patients as assessed by flow cytometry analysis. In addition, we found distinct accumulation of porphyrin
depending on cancer type (cutaneous melanoma versus colorectal cancer). These data lead to the possibility of identifying
circulating cells based on preferential accumulation of this new porphyrin in circulating tumor cells because, even
accumulated in low percentage of cells the registered intensity of fluorescence was high. Selecting the genetic markers for
circulating tumor cells is an option, but high costs and high level of know-how can be somewhat a hurdle for a rapid
evaluation. Thus our approach with a new porphyrin can be developed in an accurate and innovative fast tracking method
for circulating cancer cells, at least in colorectal cancer patients.