Increased platelet-derived growth factor (PDGF) release after laparotomy stimulates systemic tumor growth in mice

A meta-analysis to determine the oncological implications of conversion in laparoscopic colorectal cancer surgery

AIM

Laparoscopic colon and rectal cancer surgery is oncologically equivalent to open resection, but the impact of conversion is undetermined. The aim of this study was to assess the oncological outcome and predictive factors associated with conversion.

METHOD

A comprehensive search for published studies examining the associated factors and outcome of conversion from laparoscopic to open colorectal cancer resection was performed adhering to PRISMA (Preferred Reporting Items in Systematic Reviews and Meta-analyses) guidelines. Only randomized control trials and prospective studies were included. Each study was reviewed and the data extracted. Random effects methods were used to combine data.

RESULTS

Fifteen studies, including 5293 patients, met the inclusion criteria. Of these 4391 patients had a completed laparoscopic resection and 902 were converted to an open resection. The average conversion rate of the studies was 17.9 ± 10.1%. Meta-analysis showed completed laparoscopic surgery favoured lower 30-day mortality (OR 0.134, 95% CI 0.047-0.385, P < 0.0001), lower long-term disease recurrence (OR 0.634, 95% CI 0.421-0.701, P < 0.023) and lower overall mortality (OR 0.512, 95% CI 0.417-0.629, P < 0.0001). Factors negatively associated with completion of laparoscopic surgery were male gender (P = 0.011), rectal tumour (P = 0.017), T3/T4 tumour (P = 0.009) and node-positive disease (P = 0.009). Completed laparoscopic surgery was also associated with a lower body mass index (BMI; mean difference -0.93 kg/m(2) , P = 0.004).

CONCLUSION

The results suggest that conversion from laparoscopic to open colorectal cancer resection is influenced by patient and tumour characteristics and is associated with an adverse perioperative outcome. Although confounding factors such as advanced tumour stage and elevated BMI are present, unsuccessful laparoscopic surgery appears to be associated with an adverse long-term oncological outcome.

Immunologic and oncologic implications of laparoscopic surgery: what is the latest?

Laparoscopic surgery has been associated with many short-term benefits such as a shorter time to recovery, return of bowel function, less pain, and a decrease in wound infection rate. Several animal and human experiments have demonstrated an immunologic and oncologic benefit of minimally invasive surgery. Whether these results will translate into similar results in human settings is unclear. Although the first published prospective randomized clinical trial suggests better long-term outcomes for patients undergoing laparoscopic surgery, results from other ongoing randomized, controlled clinical trials are needed to verify this controversial result.

Platelet-derived growth factor (subtype BB) is elevated in patients with colorectal carcinoma

PURPOSE

Platelet-derived growth factor-BB plays a role in the development of vascular and lymphatic vessels in tumors. In this study plasma levels of platelet-derived growth factor-BB were assessed preoperatively in patients with adenomas and colorectal cancer to determine whether platelet-derived growth factor-BB is a useful marker or prognostic indicator.

METHODS

Patients with adenomas and colorectal cancer undergoing resection were assessed. Clinical and pathologic data and preoperative blood samples were collected. Plasma platelet-derived growth factor-BB levels (median, 95 percent confidence interval for median) were determined and the Kruskal-Wallis test and Mann-Whitney U test were used for analysis.

RESULTS

One hundred seventy-nine patients were studied (91 with colorectal cancer, 88 with adenomas). Preoperative colorectal cancer platelet-derived growth factor-BB levels were higher (1,771.1 pg/ml; confidence intervals, 1,429-2,065) than in the benign neoplasm group (1083 pg/ml; confidence intervals, 933-1,192, P < 0.001). In patients with colorectal cancer, a direct relationship was noted between platelet-derived growth factor-BB levels and disease severity. Despite the increase in platelet-derived growth factor-BB noted with increasing stage, the differences between the Stages 1, 2, 3, and 4 groups were not significant.

CONCLUSION

Platelet-derived growth factor-BB levels were greater in patients with colorectal cancer (vs. patients with adenoma) and rose with increasing disease severity. Unfortunately, however, the modest differences between categories do not permit accurate stage determination.

Significant reduction of laparotomy-associated lung metastases and subcutaneous tumors after perioperative immunomodulation with flt3 ligand in mice

Laparotomy has been associated with increased rates of tumor establishment and metastasis formation postoperatively in animal models. The purpose of this study was to determine the impact on postoperative tumor growth of perioperative upregulation of immune function via fetal liver tyrosine kinase 3 (Flt3 ligand). Two murine studies were carried out: the first utilized a lung metastases model, and the second involved a subcutaneous tumor model. Each study included four groups: anesthesia control (AC), AC plus Flt3 ligand (ACFlt3), sham laparotomy (OP), and OP plus Flt3 ligand (OPFlt3). Flt3 ligand was administered by daily intraperitoneal injection (10 mug/dose) beginning 5 days preoperatively and continuing for 1 week postoperatively. In study 1, A/J mice were given tail vein injections of 1.5 x 10(5) TA3Ha cancer cells on the day of surgery. The mice were sacrificed 14 days after surgery, the lungs processed, and the surface metastases counted by a blinded observer. In study 2 C3H/He mice were given a dorsal subcutaneous injection of 10(4) MC-2 cancer cells on the day of surgery. The mice were sacrificed 31 days after surgery, and the injection sites were evaluated for subcutaneous tumors grossly and histologically. In study 1, the median number of surface lung metastases per mouse was 166 in the OP group and 38 in the OPFlt3 (P = .021). Mice in the AC group developed a median 50 lung metastases per animal compared with mice in the ACFlt3 group who had a median of 10 metastases per mouse (P = .001). The OP group had significantly more metastases than the AC group (P = .048). In study 2, the percentage of animals that developed tumors in the AC, OP, ACFlt3, and OPFlt3 groups was 43, 80, 0, and 20, respectively. The incidence of tumors in the OPFLt3 group and the ACFlt3 group was significantly less than their respective control groups (P < .01). The difference between the OP and AC groups was not significant (P > .05). Perioperatively administered Flt3 ligand was associated with significantly fewer lung metastases and a lower incidence of subcutaneous tumor formation after laparotomy and anesthesia alone. Perioperative immunomodulation may limit untoward surgery-related oncologic effects.

The heparins and cancer

Heparin, and particularly low molecular weight heparin, is widely used for the treatment of patients with deep vein thrombosis (DVT) and the prevention of DVT that commonly accompanies malignancy. Malignant growth has also been linked experimentally to the function of heparin-like glycosaminoglycans (HLGAGs). In addition to the voluminous general literature on this subject, the heparin-cancer link has been the theme of at least three entire journal issues in recent months. These include the June 15, 2001 issue of Thrombosis Research, the November 2001 Supplement to Haemostasis, and the February 2002 issue of Seminars in Thrombosis and Hemostasis. Previous reviews have documented the historical development of this link that includes evidence from basic biochemistry and cell biology, studies in experimental animal model systems, and clinical trials. This concise review updates recent basic and clinical data on the heparin-cancer link that clarify mechanisms by which HLGAGs regulate the malignant behavior of cells. Electronic access to information that is increasing geometrically has become indispensable. Evidence for control of tumor cell growth by heparin-binding growth factors, tumor cell invasion by heparin-inhibitable enzyme systems, tumor cell metastasis by heparin-binding cell surface selectins, tumor angiogenesis, and tumor matrix formation related to deposition of fibrinogen/fibrin provides a secure theoretical foundation for systematic testing of this class of compounds in patients with cancer. HLGAGs may be a fundamental intermediate in the abnormal growth regulation characteristic of neoplasia that is susceptible to targeted intervention.

Plasma from patients undergoing major open surgery stimulates in vitro tumor growth: Lower insulin-like growth factor binding protein 3 levels may, in part, account for this change

BACKGROUND

Plasma from laparotomized mice has been shown to stimulate in vitro tumor growth when compared to results with preoperative plasma. This study assessed the effect of plasma from patients who underwent major open (OS) or laparoscopic surgery (LS) on in vitro tumor cell growth.

METHODS

Eighty-four patients undergoing major abdominal surgery were studied (45 OS, 39 LS). Peripheral blood was collected preoperatively (PreOP) and on days 1 (POD1) and 3 (POD3) after operation. HT29 human colon cancer cells were plated with samples of the plasma. Proliferation was assessed by cell counts and the bromodeoxyuridine incorporation assay. Insulin-like growth factor binding protein 3 was detected in plasma by Western blot analysis.

RESULTS

Increased mitogenic activity was noted in POD1 OS plasma when compared to PreOP OS plasma results (P <.005). This increase correlated with the length of incision (r = 0.58, P <.01). No differences were noted when the PreOP LS and POD1 LS results were compared or for any of the POD3 versus PreOP comparisons.

CONCLUSIONS

Major OS is associated with alterations in plasma composition that promote HT29 tumor cell proliferation in vitro. As shown, this effect was due, at least in part, to surgery-related depletion of insulin-like growth factor binding protein 3 in peripheral blood.

Laparotomy, laparoscopy, cancer, and beyond

The fate of laparoscopic methods for the treatment of cancer remains uncertain. Published middle-range oncologic results from nonrandomized studies demonstrate that laparoscopic methods are associated with an outcome comparable with results after open resection. The world awaits the 3- and 5-year oncologic results of the ongoing randomized and prospective trials. There is a possibility that laparoscopic methods may be associated with a survival benefit. Port tumors remain a concern. However, results at this writing suggest that these recurrences take place at a frequency similar to that of incisional recurrences following open cancer resection. Port tumors currently are viewed as local recurrences. Traumatization of the tumor at the time of resection is thought to be the most important surgery-related risk factor. The demonstration of a survival benefit in a randomized trial would likely have a tremendous impact on the surgical world. Avoidance of laparotomy-related immunosuppression and tumor stimulation, both of which have been well demonstrated in animal studies, theoretically, might account for differences in cancer outcome. The early postoperative period may be a critical time during which the fate of many cancer patients is determined. It is possible that this may be an ideal time frame for antitumor immunotherapy because the tumor burden is at its lowest, and because immunotherapy, unlike conventional chemotherapy, is unlikely to have a negative impact on wound and anastomotic healing. Perioperative nonspecific upregulation of immune function via pharmacologic means may improve long-term oncologic results. Similarly, preoperative tumor vaccines might provide patients with a specific means of combating any remaining tumor cells after curative resection. The results of several recently completed murine studies support both of these ideas. Finally, early postoperative administration of monoclonal antitumor antibodies might provide patients with specific means of combating any remaining tumor cells after curative resection. The introduction of advanced minimally invasive techniques nearly a decade ago has led to new methods of approaching malignant tumors that have the potential to have an impact on the oncologic outcome of cancer patients. This decade-long journey also has led to new insights regarding the impact of surgery on the patient. It also has alerted us concerning the importance of the immediate postoperative period in the patient's ongoing struggle against the tumor. These insights hopefully will lead to better surgical methods and new perioperative adjuvant therapies that will increase the rate of survival and reduce the recurrence rates for cancer patients.