Long process and due to strict deadline, project was stopped.

This will be a pilot study involving 5 patients diagnosed with colorectal carcinoma and treated with pre-operative chemotherapy and external beam radiation therapy at the Jewish General Hospital, whom will very soon undergo surgery. Participants will be sensitized by the instillation of a 250 mL enema containing 1.6 mmol of HAL. The enema will be administered with a plastic tube with an inflatable blocking balloon to prevent leakage of the enema. Fluorescence sigmoidoscopy will be performed with white light then blue excitation light after retention of the enema for 60 minutes, followed by a rest time of up to 30 minutes before rectoscopy. Red fluorescence should be induced by illumination with blue light. Pictures with and without fluorescence will be taken. The patients will undergo a colectomy (partial or complete) within the next 2-3 days and the surgical specimens will be collected for further fluorescence microscopy studies and pathological correlation of fluoresce with malignant pathology/histology as the gold standard. The total concentration of porphyrins in the patients' urine and serum will be recorded before sensitization, immediately after sensitization (instillation of the enema), and approximately 24 hours after sensitization. The patients' pre-and-post operative liver function tests will be measured. Adverse events will be reported by direct questioning of all patients with regards to photosensitivity and gastrointestinal symptoms (nausea, vomiting), and by measuring blood pressure and heart rate. Our objectives and endpoints are: 1) to determine if fluorescence with photodynamic diagnostics is selective for colorectal cancer, 2) to determine if photodynamic diagnostics has the potential to improve the detection of malignant cell after neoadjuvant chemotherapy and radiation, and 3) to determine if photodynamic diagnostics can provide an accurate depiction of the extent of disease burden not visible with normal white light sigmoidoscopy to the naked human eye.

Inclusion Criteria:

• Patients older than 18 years of age with diagnosed colorectal cancer.
• Colorectal cancer patients treated with Chemotherapy and external beam radiation therapy

Exclusion Criteria:

• 1) Liver cirrhosis
• 2) Acute or chronic hepatitis
• 3) Elevated liver function tests of unknown etiology with elevation of transaminases of more than 3 times normal levels
• 4) Known porphyria
• 5) Pregnancy
• 6) Expected lack of compliance