Laser-induced endogenous fluorescence as possible response predictor of neoadjuvant treatment of rectal cancer

Summary form only. Response to neoadjuvant treatment (radiochemotherapy: RCT; radiochemotherapy with hyperthermia: HRCT) can not be monitored precisely by present clinical diagnostic tools. It was observed previously that autofluorescence spectra of tumors recorded ex vivo or in vivo exhibit strong porphyrin fluorescence bands. Following a prospective, randomized protocol to compare hyperthermic radiochemotherapy with radiochemotherapy alone for treating regionally advanced rectal cancer, we have recorded time-gated autofluorescence spectra and evaluated changes in PpIX fluorescence intensity of primary tumors and surrounding mucosa. Our aim is to demonstrate that laser-induced fluorescence intensity of endogenous porphyrins can be used as marker for biological tumor response.