1. Department of Surgery, Ohara General Hospital, Fukushima, 960-8611.
2. Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
3. Department of Pathology, Ohara General Hospital, Fukushima, 960-8611.
4. Second Department of Surgery, Fukushima Medical University 960-1295, Japan.