We investigated the time course of hematoporphyrin oligomer uptake in squamous cell carcinoma transplanted into C3H mice after intraperitoneal injection by measuring its fluorescence intensity. The intensity peaked 83 hours after the injection. The tumors disappeared after an average of 4.40 days with a single application of photodynamic therapy or microwave hyperthermia 83 hours after hematoporphyrin oligomer injection. However, all the tumors treated with these single modalities regrew within 4 weeks after the treatments. Therefore, we investigated the therapeutic effect of microwave hyperthermia in combination with photodynamic therapy. As a result, the combination effect was strongest when high-dose therapy was used as the first choice, irrespective of the order of the treatments, and no tumor regrowth occurred for 45 days.
Moreover, we applied above-mentioned single and combined modalities to the same carcinoma 48 hours after PH-I126 intravenous injection. The same tendency was observed in the combined condition. However, the antitumor effects were stronger in the single modalities than in the combined modalities, although the tumor regrowth occured after its disappearance.
