Abstract. The therapeutic effect of radiotherapy using linear accelerators for relatively large tumors of more than several centimeters in diameter is reduced to one third due to a large number of hypoxic tumor cells and a significant amount of anti-oxidative enzymes including peroxidase/catalase. The most effective method by which to inject hydrogen peroxide into tumor tissue was examined. This proved difficult as 3% w/v hydrogen peroxide solution (Oxydol) is an antiseptic agent for skin lesions. Thus, injection into an affected lesion may result in hydrogen peroxide soaking into a body cavity, possibly causing an intra-arterial oxygen embolism. This study aimed to identify the most effective combination of drugs containing hydrogen peroxide in order to relieve local pain at the injection site and preserve high intratumoral oxygen concentration. Hyaluronate-hydrogen peroxide was identified as the most effective combination of drugs containing hydrogen peroxide for the preservation of high intratumoral oxygen concentration for 24 h following intratumoral injection with the agent. Based on the results, the clinical application of a novel enzyme-targeting radiosensitization treatment, Kochi Oxydol-Radiation Therapy for Unresectable Carcinomas (KORTUC), was initiated for malignant tumors including advanced breast cancer, soft tissue sarcoma and cervical lymph node metastasis. Moreover, we have developed KORTUC III for locally advanced hepatocellular carcinoma and KORTUC IV for locally advanced pancreas cancer (stage IVa).

We introduced non-surgical therapy with a novel enzyme-targeting radiosensitization treatment, Kochi Oxydol-Radiation Therapy for Unresectable Carcinomas, Type II (KORTUC II) into early stages breast cancer treatment. The purpose of this study was to examine changes in tumor shadows and microcalcifications on mammography (MMG) following KORTUC II for elderly patients with breast cancer. We also sought to determine whether MMG was useful in evaluating the therapeutic effect of KORTUC II. In addition to MMG, positron emission tomography-computed tomography (PET-CT) was performed to detect both metastasis and local recurrence. In all 10 patients, tumor shadows on MMG completely disappeared in several months following the KORTUC II treatment. The concomitant microcalcifications also disappeared or markedly decreased in number. Disappearance of the tumors was also confirmed by the profile curve of tumor density on MMG following KORTUC II treatment; density fell and eventually approached that of the peripheral mammary tissue. These 10 patients have so far have also shown neither local recurrence nor distant metastasis on PET-CT with a mean follow-up period of approximately 27 months at the end of September, 2010. We conclude that breast-conservation treatment using KORTUC II, followed by aromatase inhibitor, is a promising therapeutic method for elderly patients with breast cancer, in terms of avoiding any surgical procedure. Moreover, MMG is considered to be useful for evaluating the efficacy of KORTUC II.

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