Temperature-associated regression of walleye dermal sarcoma tumors

A temperature-associated model for tumor regression was established using t he virally induced walleye dermal sarcoma (WDS). In one trial, walleyes Sti zostedion vitreum received a topical application of a cell-free dermal sarc oma tumor filtrate and were allowed to develop grossly visible tumors at 15 degreesC for 5 months. The walleyes were then randomly placed into one of three temperature treatment groups (10, 15, or 20 degreesC) and grossly exa mined at monthly intervals for the presence of tumors. The rates of tumor r egression (calculated as incidence densities) were compared across groups. The regression of WDS tumors was associated with increased temperature over the course of the 10-month study. The incidence of tumor regression was si gnificantly higher in walleyes held at 15 or 20 degreesC than in those held at 10 degreesC. In another trial (which more closely replicated the temper atures of Oneida Lake, New York, during the early spring, when WDS transmis sion is thought to occur), tumors were allowed to develop at 10 degreesC fo r 1 month and then at 1.5 degreesC for 5 months, before the temperature was increased to 20 degreesC. In this trial, walleyes were tagged with transmi tters so that they could be individually identified during the monthly surv ey of tumor status. Rates of regression observed were less than those in th e first trial.