Incidence of lymph node metastases after piecemeal laser-surgical and en bloc cold steel resection of auricular VX2 carcinoma. A comparative study.

The CO2 laser surgery has become a widely used clinical treatment in otorhinolaryngology. In advanced neoplastic disease of the head and neck it is often difficult and even impossible to expose well the whole tumor through the surgical laryngoscope. In such cases the tumor is usually divided with the CO2 laser in several parts, which are excised separately. This approach seems opposed to the basic principles of oncologic surgery, where the tumor should not be touched in order to avoid local recurrences or metastatic spread. The proponents of the piecemeal resections refer back to few morphological and clinical studies, which show no evidence of increased incidence of metastases after the piecemeal resection. On this background the aim of the present study was to compare the piecemeal laser surgical complete (R0) resection with cold steel complete (R0) en bloc resection of tumors in an animal model. For both surgical approaches the incidence of local recurrences, regional and distant metastases had to be compared. After randomization to the both study arms in 143 male New Zealand White rabbits a VX2 squamous cell carcinoma was induced on the auricle. On day 8 a complete resection of the tumour was performed: for the first group - with cold steel resection en bloc; for the second group the cancer was transected by the CO2 laser following which it was removed in two pieces - piecemeal laser-surgical resection. On the 42nd postoperative day all animals were sacrificed and subjected to evaluation of the tumoral spread. Compared on the incidence of LN metastases the two therapeutic groups showed significant differences. Twenty-five percent of the animals with en bloc cold steel had metastases to regional lymph nodes, whereas forty-seven percent of the laser piecemeal group had metastatic nodal involvement. The incidence of distant metastases was similar for both study groups - 12.3% for the en block resection group and 7.7% for the piecemeal laser resection group. In this experimental setting the piecemeal laser surgical resection achieved better local results, but lead to more metastases (mainly lymphatic ones), than the cold steal en bloc resection. However, it is unlikely that tumor cells disseminated from the resection line itself caused this difference, as the vessels here were occluded by the laser. Mechanisms, which could explain the observed difference include dissemination through the walls of the intratumoral or peritumoral lymphatics. Piecemeal laser resection may decompress intratumoral pressure and release intra and peritumoral lymphatics, causing a flood of tumor emboli. Changes in the permeability and the lymph/blood flow caused by the local laser heat could have similar effect. Additionally mechanical trauma to the tumor mass itself or explosion-like tumor cell spread into the lymphatic network due to the applied laser energy could also precipitate metastases