Comparison of recurrence patterns in human lymphoma and experimental leukemia

Recurrence patterns are reviewed for an experimental murine leukemia (L1210) and for Hodgkin's disease in man. Two distinctive patterns are evident, with recurrence of tumor exposed to ionizing radiations occurring significantly later than for nonirradiated tumor. In the experimental leukemia studies, the prolonged recurrences (survival times) of mice inoculated with irradiated cells was demonstrated to result from a retarded growth rate of sublethally damaged leukemic cells which survived irradiation and continued to proliferate. One can only speculate as to the mechanism of delayed recurrences in irradiated sites of Hodgkin's disease patients as compared to earlier recurrences in nonirradiated regions. However, recognition of these recurrence patterns may assist in the prediction of tumor control probabilities in irradiated versus nonirradiated areas on a differential basis.