Augmentation of the systemic host anti-tumor response through laser excision

This study examines whether primary laser excision results in augmentation of the systemic host anti-tumor response to tumor rechallenge. Single R3230AC mammary tumor implants, (0.5 x 0.5 x 1.0 mm), were grown in 112 female Fisher 344 rats. The animals were randomized. Group S tumors were excised by scalpel. Group E was excised with a Surgistat electrocautery (Valley Labs, Boulder, CO). Group CS was excised with a Sharplan 1100 CO2 laser (Sharplan, Allendale, NJ) at 25 watts (W) continuous wave (CW) (0.2 mm spot size) and the wound was "sterilized" with a 5-mm spot size by gently heating the tissue without blanching. Group K was excised with a KTP/532 laser (Laserscope, San Jose, CA) at 17 W CW using a 400 microns fiber. Group Y was excised with a Sharplan 2100 Nd:YAG laser set at 15W CW using a 0.2 mm clear sapphire tip. A second tumor implant, (0.5 x 0.5 x 1.0 mm), was placed at a remote site 14 days postoperatively. An unoperated control group was implanted. Secondary tumor volumes were measured for 36 days and the mean tumor volumes (MTV) were statistically compared. The MTV in groups CS, K, Y, and E was less than control (P less than 0.01). The MTV in groups CS, K, Y, and E was less than group S, although this was not statistically different. Lasers and cautery appear to increase the host response against subsequent tumor challenge. This study corroborates earlier studies of other modalities. Further studies to determine whether this host sensitization is an immune response and to elucidate the mechanisms of this effect are warranted.