The Natural History of the Lakeland Sarcoma (Leiomyosarcoma)

Summary

A transplantable tumor which originated in the uterus of a Sprague-Dawley rat and appears to be a leiomyosarcoma is described. The tumor has been studied through fourteen transplant generations. After the fifth generation, the tumor grew more rapidly, became more anaplastic, and metastasized more frequently. The rate of growth was linear during the first 8 weeks, and no regressions have been observed. The transplants made by the trocar method grew in 94 per cent of females and 75 per cent of males. In the tumor-bearing animals, 91 per cent developed metastases; the axillary and pelvic lymph nodes were involved in 82 and 57 per cent of cases, respectively. The lungs were involved in 50 per cent of cases. In 127 tumor-bearing animals, no metastases have been found in any tissue except muscle, lymph nodes, and lungs. After the fifth generation, the average survival time has been 10 weeks, with a range of 6–19 weeks.