Therapeutic gain of local and radical resection combined with postoperative radiation for murine fibrosarcomas.

Resection of 8-mm fibrosarcomas (FSaII) growing in the right leg of syngeneic C3H/Sed mice was performed under a dissecting (x8) microscope. Local and radical resection achieved 20% (5/25) and 48% (12/25) tumor control, respectively. TCD80s (average dose expected to control 80% of irradiated tumors) for radiation alone given as one fraction per day for 5 consecutive days were 73.1 and 118.0 Gy for the microscopic and 8-mm tumors, respectively. Radiation therapy started at 4 or 7 days following local or radical resection enhanced both the local tumor control and the treatment-related morbidity represented by leg shortening. From enhancement ratios (ERs) for tumor control (TCD80 for radiation alone/TCD80 for postoperative radiation) and for leg shortening (dose for 5-mm leg shortening for radiation alone/postoperative radiation) values, therapeutic gain factors (TGFs) were derived as ER tumor/ER leg shortening. These were 1.3 and 1.4 for local and radical resection followed by radiation started on the 7th postoperative day, respectively. Corresponding figures for radiation started on the 4th postoperative day resulted in 1.2 for both resection procedures.