[Subrenal capsule assay for chemosensitivity test (II)--Sequential changes in the implanted tumor tissue and histological findings].

We carried out fundamental subrenal capsule assay methodology, using tumor specimens of human cancer xenografts (breast cancer and colon cancer) serially transplanted into nude mice. With regard to sequential changes in the tumor grafts implanted under the renal space of immunocompetent mice, tumor size was largest macroscopically around day 6 after inoculation, and later involuted gradually. Histological findings showed that implanted tumor tissues were preserved to a moderate extent until day 4 after inoculation, but leukocyte infiltration by host reaction had begun by day 4, and tumor tissues were almost replaced by host reactive tissues on day 6. Labeling index scoring did not indicate growth of implanted tumor cells. We found that macroscopic tumor size was largest around day 6 because we measured tumor size with involved leukocyte infiltration, and the macroscopic tumor did not represent the true extent of the tumor tissue.