A series of syngenetic hamsters were challenged with a lethal tumor. Animals who received either a heat-treated extract of the tumor or an extract made from tumor-challenged lymph nodes had a 30% survival, whereas all control animals died following tumor challenge.
Castillo J, Goldsmith HS. Immunological Competence of Heat-Treated Extracts of Tumor or Lymph Nodes. Arch Surg. 1973;106(3):322-324. doi:10.1001/archsurg.1973.01350150056016