Small numbers of hepatoma cells were transplanted intradermally in the flanks of strain-2 guinea pigs to study the course of growth when the size of the transplant was comparable to an early stage of spontaneous cancer. The incidence of positive transplants and the time for the appearance of the tumor were related to the number of cells transplanted. When 40,000 or 80,000 cells were transplanted, tumor developed at 98-100% of the sites, but only 60% of the sites that received 5,000 cells developed tumors. When 40,000 or 80,000 cells were injected, a measurable tumor appeared within 10 to 12 days, whereas when 20,000 cells were injected, 20 days were required. The size of the tumor was determined by measuring the average diameter, (length + width)/2, of the tumor. The growth rate of the developed tumor is independent of the number of cells transplanted. The initial growth rate of the tumors was 0.32 mm/day. When the diameter of the tumor was between 14 and 20 mm, the growth rate decreased to 0.26 mm/day; and regression began when the tumor diameter reached 20 mm.

Related Articles