Surgical therapy for solid tumors of the abdomen and retroperitoneum carries a history replete with dogma and folklore. Concerns of tumors spreading during surgery are often shared by patients and surgeons. Various measures have been devised to minimize contamination and dissemination of neoplastic cells during solid tumor surgery. Minimally invasive approaches to resection of solid tumors are growing exponentially. Along with these new approaches, new anxieties have been expressed regarding oncologic outcomes for these patients, as reports of port-site metastases and widespread tumor dissemination have surfaced.
Fueled by market interests and improvements in technical skills and instrumentation, potential applications for minimally invasive surgery exploded during the 1990s. Interestingly, centers of excellence for tumor surgery did not keep pace with the laparoscopy boom, primarily due to early reports of tumor dissemination and port-site metastases.[1-4] Associations were drawn between CO2 pneumoperitoneum and wound recurrence, and progress stalled. Furthermore, oncologic surgical training was relatively devoid of instructors familiar with minimally invasive methods.
Results of several recent large retrospective series and prospective trials have allayed initial concerns that laparoscopic approaches result in inferior cancer outcome.[5-7] Graduating surgical residents are assisting with more advanced laparoscopic procedures, and momentum for minimally invasive techniques for cancer surgery has grown. This article reviews historical, theoretical, and technical aspects of laparoscopic resection of solid tumors.
Surgery and Cancer: Fact vs Myth
Before examining how laparoscopy impacts cancer outcome, it is necessary to review the associations of standard surgical therapy (ie, laparotomy) and malignancy. It is a common concern that surgery can promote tumor spread. This view is shared both by laypersons and health-care professionals, and is supported by some animal and human data for primary and metastatic disease.
Animal data provide some fascinating examples. Partial hepatectomy can stimulate growth of experimentally delivered hepatic metastases. It is postulated that preexisting micrometastases in the remnant liver, which under normal circumstances remain relatively dormant, are subject to growth factors expressed during liver regeneration and are thus stimulated to multiply.[9-11]
Another example comes from the groundbreaking work of Judah Folkman. Circulating proteins (endostatin and angiostatin) produced by primary flank tumors (Lewis lung carcinoma) in mice, which suppress growth of lung metastases, were identified. In this model, removal of the flank tumor results in growth of lung lesions, which can be reversed by administering exogenous, purified endostatin. While human trials have not confirmed these preclinical findings, the implications of these discoveries are dramatic for cancer surgery.
Human data are less conclusive on the topic of surgery and cancer recurrence. Most reports are retrospective and subject to many confounding variables. For example, a recent report on recurrence following surgical therapy for breast cancer showed that 27% of premenopausal women with node-positive disease experienced recurrence or progression within 10 months of surgery, which was significantly greater than in node-negative or postmenopausal women. The authors of this report conclude that a sudden acceleration of the metastatic process by surgery could explain these risk dynamics.
Several mechanical aspects of operation, the most obvious being careless technique with inadequate tumor handling and incomplete resection, are implicated in promoting tumor growth and recurrence. Dissemination of tumor cells from the primary lesion via lymphovascular channels is associated with reduced survival in many tumor models.[14-16] Furthermore, intraoperative tumor manipulation can increase the number of circulating tumor cells in the bloodstream. As such, several maneuvers have been described to minimize this occurrence. Vascular ligation prior to manipulation of tumor-bearing organs was first proposed in 1967 by Dr. Rupert Turnbull, with his description and retrospective reporting of the "no touch" technique. Although prospective evidence does not support improvement in cancer outcome using the "no touch" technique for colorectal cancer, recent reports recommend similar ideology for pancreatic cancer[18,20] and liver cancer.[21,22]
Other commonly used methods to minimize tumor recurrence include irrigating with sterile water to lyse potentially free-floating cancer cells in the peritoneal cavity, changing surgical instruments after each use to avoid cross contamination, and placing wound protectors for specimen extraction. Table 1 lists several theories on how surgery may negatively influence cancer outcome, as well as measures suggested to improve outcome. Surgeons that routinely treat solid tumors of the abdomen use some or all of these techniques to limit tumor spread during operation, despite a lack of level I evidence supporting the benefit of such practices.
In addition to mechanical factors and circulating growth factors, alterations to the host immune system as a result of surgical stress are thought to negatively impact tumor recurrence. The associations between immune function, cancer, laparotomy, and laparoscopy are discussed later in this article.