Following two decades of evolution, the laparoscopic approach has been well established in the surgical armamentarium. Shorter hospital stay, less postoperative pain, decreased wound infection rate, and faster recovery have been revealed as advantages of laparoscopic surgery [1]. Those benefits are also encountered after laparoscopic colectomy (LC), and despite the initial skepticism, the ambiguous viewpoints regarding port-site tumor recurrence, and the slow expansion of the method, oncologic equivalency with its open counterpart has been well proven in randomized trials [2–5].

Although various aspects of the laparoscopic approach in surgical treatment of benign and laparoscopic colorectal diseases have been extensively studied, sufficient and firm data regarding relative differences in immunologic response between conventional, open colectomy (OC) and LC are still not sufficient to draw definite, useful, and clinically applicable conclusions [6]. Existing studies, though, tend to support better preservation of immunologic function after LC [7]. However, assessment of the systemic inflammatory response and comparison of various inflammatory cytokines between the two approaches in colon cancer surgery by different research groups have been dominated by conflicting results [8]. What is also underexamined is the presence of potential differences with the open procedures at later postoperative days, when the immunologic advantage of laparoscopic surgery would be more demanding to demonstrate, in order for earlier administration of adjuvant treatment to be better justified.

Based on the imperative need to clarify the potential immunologic advantage of LC, especially at later postoperative days, this study attempts to compare the inflammatory response of patients who underwent OC and LC for colorectal cancer up to the end of the first postoperative week. Interleukin 1 (IL-1), interleukin 6 (IL-6), interleukin 8 (IL-8), interferon γ (IFN-γ), and C-reactive protein (CRP) are proinflammatory cytokines with central systemic role and are detected and analyzed in the present comparative study.

Patients and methods

Amongst the 36 patients who were treated by laparoscopic colectomy with therapeutic intent between December 2007 and June 2009 at the 1st Propaedeutic Surgical Department of Athens University, 30 patients elected to enter the study, and were age, sex, stage, American Society of Anesthesiologists (ASA) score, and colectomy type-matched with 30 colorectal cancer patients derived from a cohort of 120 patients who had undergone open colectomy during the same time period and had blood drawn at the defined assessment timepoints of the study. To perform this matched case–control study, we used a matching algorithm based on the type of surgery performed according to tumor location (right colectomy, sigmoidectomy, low anterior resection). Patients were classified and arranged according to colectomy type. An independent reviewer, who was blinded to all clinical data except the matching criteria, matched the patients manually one by one on the basis of the remaining criteria [tumor–node–metastasis (TNM) stage, age, sex, and ASA score] (Table 1).

Table 1 Matching characteristics of patients undergoing open and laparoscopic colectomy
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All patients included had adenocarcinoma of the colon or the rectum confirmed by pathology. Exclusion criteria were age older than 80 years or younger than 18 years, presence of severe comorbidities (ASA score >3), presence of immune compromise, hepatic or renal insufficiency, history of inflammatory bowel disease or inherited colorectal polyposis syndrome, malnutrition, presence of metastatic disease, neoadjuvant treatment, emergency surgery, surgery for complicated cancer (i.e., large bowel obstruction), complications during postoperative course, and conversion at laparoscopic colectomy. Patients in both groups had generally uneventful recovery.

Institutional review board (IRB) approval has been obtained, and informed consent was given by the patients. Preoperative data, such as demographics and medical history, were recorded. All patients received mechanical bowel preparation, and intravenous chemoprophylaxis was also administered. None of the patients received blood transfusion.

Blood from peripheral venipuncture was taken from the patients preoperatively, 24 h after completion of the operation, and at the 7th postoperative day (POD). The blood sample was centrifuged, and part of the collected serum was stored at −20°C whereas the rest was used to measure CRP by immunonephelometry. The stored specimens were assayed by enzyme-linked immunosorbent assay (ELISA) for IL-1a, IL-6, IL-8, and IFN-γ. The concentrations in serum were measured with a commercially available enzyme-linked immunosorbent assay kit (human ELISA kits, Mergenix EASIA®; Immunotech Marseille, France and DSX system Dynex; Magellan Biosciences).

The patients underwent typical segmental colorectal resections, either open or laparoscopic, by surgeons experienced in both techniques. All patients received general anesthesia with standardized anesthetic techniques. A urinary catheter and a nasogastric tube were routinely used. During the conventional procedures, an abdominal midline incision was undertaken and either a stapled or a handsewn anastomosis was created depending on surgeon preference. During the laparoscopic operations, CO2 pneumoperitoneum was created via Hasson technique and maintained intraoperatively at pressure of 12–14 mmHg. Standardized equipment was used in all the laparoscopic operations, including a 30º laparoscope; at the end, small (<10 cm length), transverse or vertical, peri- or infraumbilical incisions were used for specimen extraction and anastomosis (right colectomies). Sites and number of trocars were generally standardized to the corresponding large bowel section removed each time. Oncologic principles were ascertained and preserved in both operational procedures.

All data were collected and statistical analysis was undertaken with SPSS statistical package version 16.0. Nonparametric tests were used for statistical analysis. Changes of examined measured values of inflammatory markers with time were analyzed with Wilcoxon’s signed-rank test comparing follow-up values with baseline, as well as timepoint values in between (i.e., 24 h versus 7 days). Differences between examined subgroups of patients (open versus laparoscopic) were analyzed by Mann–Whitney U tests. Statistical significance was set at p < 0.05.

Results

No significant differences existed between groups in terms of basic demographic and pathologic data (Table 1). Except for length of operation time, which was greater for LC (p < 0.05), body mass index, concurrent illness, number of retrieved lymph nodes, tumor size, etc. did not differ significantly between the two groups.

Examined cytokines and CRP values at the three assessment timepoints (preoperatively, at 24 h, and at the 7th POD) are presented in Table 2. CRP and IL-6 postoperative values at 24 h and at the 7th POD were significantly higher than baseline for both groups (p = 0.001), but the respective values at the 7th POD were less than at 24 h (p = 0.001) (Table 2). Changes in IL-1 and IL-8 levels were not statistically significant between assessment timepoints or between groups of patients (Table 2). Postoperative IFN-γ measurements were significantly higher compared with baseline for the LC group only (p = 0.03).

Table 2 Values (mean ± standard error of the mean, SEM) of measured parameters: IL-1, interleukin-1 (pg/ml); IL-6, interleukin-6 (pg/ml); IL-8, interleukin-8 (pg/ml); IFN-γ, interferon-gamma (relative values); CRP, C-reactive protein (mg/dl)
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Comparing the relative differences of cytokine concentrations (i.e., the difference of INF-γ values between baseline and 24 h versus the difference of IL-1 values between baseline and 24 h), it was found that the IFN-γ increment noted in the laparoscopic group was more accentuated than the respective IL-1 value changes at 24 h and at the 7th POD (p = 0.09 and p = 0.02, respectively). Similarly, IFN-γ levels at 24 h and at the 7th POD were significantly less for the OC group compared with the LC group of patients (p = 0.001) (Table 2; Fig. 1). No correlation was revealed between measured serum values and other parameters such as age, sex, tumor location, or stage of disease.

Fig. 1
figure 1

Significant differences of interferon-gamma (IFN-γ) concentrations between open and laparoscopic colectomy at 24 h and 7 days postoperatively

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Discussion

Operative procedures have major impact on patient homeostasis, expressed mainly by an immune response compromise [9]. The unavoidable inflammatory response involves regional and systemic release of cytokines, hormones, acute-phase proteins, eicosanoids, and other substances by surgical manipulation-activated immune cells. This stress response is responsible for the attenuated cell-mediated immune response and the probable immune compromise which may contribute to postoperative morbidity [9–12]. The impaired immune response has been well appreciated in cancer patients [12–15]. In this sensitive group of patients, fast and uneventful recovery is a prerequisite for timely administration of adjuvant treatment.

Measuring the levels of circulating cytokines at several postoperative timepoints is indicative of the degree of inflammatory response in both conventional and laparoscopic techniques. Initially, better preservation of patient immune status was proved with the conduction of common operations, such as cholecystectomy, by laparoscopic means [16–23]. That was attributed to the CO2 pneumoperitoneum, the less and gentler tissue manipulations, and the smaller surgical wounds [16–23]. While the immunological benefits may be expected to be pronounced in procedures where the access incision constitutes a proportionally large burden of injury, such as in laparoscopic cholecystectomy, in other procedures, where the intra-abdominal insult is more major, such as laparoscopic colectomy, the evidence remains, in many aspects, unclear. This is due to the fact that, although the humoral response after open and laparoscopic colectomies has been the subject of intense investigation, heterogeneity in surgical indications, humoral factors measured, measurement timing, and method of sample analysis do not permit firm conclusions. As a consequence, results are conflicting and opinions remain divided [24–36, 39–44] (Table 3). Applying the methodology of a matched case–control study, we managed to diminish the influence of some potentially immunologically implicated factors and to elucidate whether there are any real differences between some of the known involved cytokines easily measured in patients’ serum.

Table 3 Summary of studies on measured inflammatory cytokines at various timepoints between laparoscopic and conventional colectomies for cancer
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In accordance with our results, the measured CRP was not significantly different between the two approaches in several studies [24–30]. To the contrary, according to other groups, lower CRP values were demonstrated during the early postoperative days after laparoscopic colectomy [31–34].

In the few studies dealing with IL-1, no appreciable differences have been noticed, as in the current study [35, 36]. Nevertheless, IL-1b exhibited significantly higher peak serum levels at 2 h after open surgery compared with laparoscopic surgery for rectosigmoid carcinoma in one study [36]. Without any significant findings in our study, IL-8 remains the least studied interleukin in this setting [28]. IL-8 is a potent chemoattractant for neutrophils and lymphocytes, as well as an angiogenic growth factor that promotes wound healing [37]. Wu et al. [28] are the only other researchers to have comparatively assessed IL-8, in the serum of patients at 2 and 24 h and 4 days postoperatively; only at 2 h was a significant difference ascertained, with lower levels after laparoscopic procedures. Based on the much higher local IL-8 expression than the systematically measured levels, the same group accentuated the idea of compartmentalization of cytokines, pointing out that what is measured systemically represents only a small fragment of what is generated locally [28]. Such observation may render real inflammatory response comparisons even more difficult.

IL-6 is considered to be a major mediator of the acute-phase protein response following injury, and in comparison with other cytokines, the concentration of IL-6 is most consistently increased in the circulation of injured patients [38]. Rationally, this is the most studied serum interleukin after laparoscopic and open colectomies [24, 25, 27–29, 31–36, 39–42]. Although discrepancy still characterizes the results on IL-6, most studies agree on the ameliorated inflammatory response after laparoscopic colectomy in the first few postoperative hours, as far as it concerns lower IL-6 levels. In our study that focused on the end of the first postoperative day, such a difference was not apparent. Even though certain studies support significantly higher IL-6 levels extending to 24 h after open versus laparoscopic colectomy [25, 32, 33, 42, 45], others are in keeping with the results derived from our study [27–29, 34, 39–41, 44]. At later postoperative days no difference between the two procedures has ever been revealed [27, 29, 34].

Excluding a small portion of the studies and our study, the rest have not examined any potential inflammatory differences at the end or after the first week [27, 31, 34]. From that time on, following assurance of well-healed anastomosis and surgical trauma, administration of postoperative chemotherapy could be considered; taking into consideration that oncological outcomes may be improved by laparoscopic techniques as a result of diminished inflammatory response [45], restoration of deranged inflammatory cytokines and of required immunologic adequacy at such potential chemotherapy-induction timeframes may be of paramount importance.

Our principal novel finding, not previously studied, is the significantly higher levels of INF-γ after laparoscopic colectomy, a difference that was also maintained at the 7th postoperative day. IFN-γ is a stimulator of human leukocyte antigen (HLA)-DR expression on the surface of antigen-presenting cells, monocytes, and macrophages, contributing to better presentation of peptide segments of the antigen to T helper lymphocytes so that the processing of the antigens in the cognitive phase of the immune response is adequately preserved [46–48]. In response to antigenic stimulation, naive T cells differentiate into either Th1 or Th2 subsets with relatively restricted profiles of cytokine production. Th1 cells produce IL-2 and INF-γ, which activates macrophages, and they are the principal effectors of cell-mediated immunity and of the delayed-type hypersensitivity reaction [7]. Th2 cells produce IL-4, IL-5, and IL-10, which activate antibody production by B cells and suppress cell-mediated immunity [7]. So, IFN-γ indicates better preserved cell-mediated immune function [7, 30, 46–49]. A study by Fujii et al. [50] showed increased production of INF-γ representing Th1 function and decreased production of IL-4 representing Th2 cell function after laparoscopic distal gastrectomy in gastric cancer patients. The authors concluded that laparoscopic distal gastrectomy contributes to preservation of postsurgical Th1 cell-mediated immune function [50]. The sustained increment of this immunologically beneficial agent in the context of laparoscopic colectomy, as well as its more striking increment in relation to IL-1 value changes in the laparoscopic group, should be taken into serious consideration and merit further exploration, as such effects may provide a theoretically basis for earlier administration of chemotherapy.

In conclusion, this study adds to the accumulating literature data on inflammatory response after laparoscopic and open colectomies, revealing the previously inadequately measured INF-γ as a potentially important indicator, which seems to have a more active presence following laparoscopic colectomy, potentially contributing to an immunologic “advantage” by counteracting “harmful” cytokines such as IL-1. Further work is necessary to further establish an immunologic advantage of laparoscopic colectomy in cancer patients.