Effect of tumour location on selective uptake and retention of phthalocyanines.

The effect of anatomical site of tumour growth on selective uptake and retention of chloro-aluminium sulphonated phthalocyanine (ClAlSPc) was determined using the murine colorectal carcinoma (Colo 26). Tumours were established in the liver, spleen, kidney, lung, thoracic cavity and s.c. flank region of syngeneic BALB/c mice and animals received 10 mg/kg ClAlSPc by i.v. injection. Colo 26 growths at s.c., intra-pulmonary, intra-thoracic or intra-renal sites took up and retained greater amounts of ClAlSPc than did adjacent normal tissues. Such selective retention of ClAlSPc by neoplastic tissue was not observed when Colo 26 was grown in the spleen, where tumour and normal tissue took up about the same amounts, or the liver, where normal tissue took up more ClAlSPc than either directly implanted or metastatic tumours. ClAlSPc ratios found in tumour/adjacent tissue may vary for a single tumour growing at different anatomical sites and such variability could have a distinct effect on the efficacy of photodynamic therapy of cancer.