Plasma extracellular cold inducible RNA-binding protein levels are elevated for 1 month post-colectomy which may promote metastases

Abstract

BACKGROUND

Cold-inducible RNA-binding protein (CIRP) is related to a family of stress-induced RNA-binding proteins. It is primarily found in the nucleus, where it regulates transcription. Under stress, CIRP translocates to the cytoplasm where it modulates translation; a subset is secreted as extracellular CIRP (eCIRP) which is a damage-associated molecular pattern (DAMP) molecule that stimulates the production of inflammatory mediators. Elevated blood eCIRP levels may foster immune tolerance and facilitate tumor growth. Increased CIRP levels have been noted in various malignancies including colorectal cancer (CRC). This study’s objective was to determine plasma eCIRP levels before and after minimally invasive colorectal resection (MICR) for CRC.

AIM

To assess plasma eCIRP levels prior to and following minimally invasive colorectal resection in the context of cancer pathology.

METHODS

MICR patients from an IRB-approved data/tissue bank for whom plasma samples were available were eligible. Plasma specimens were obtained preoperatively (preop) and at least 3 time’s postop [between postoperative day (POD) 1-41]; late samples were grouped into 7-day blocks and were considered separate time points. eCIRP levels were assessed via enzyme-linked immunosorbent assay (pg/mL) and results presented as mean ± SD, analysis with Wilcoxon paired t-test).

RESULTS

A total of 83 CRC patients who underwent MICR [colon 66%, rectal 34%; laparoscopic-assisted (LA), 70%; hand-assisted laparoscopic (HAL), 30%] were studied. The mean preop eCIRP level was 896.8 ± 757.0 pg/mL. Elevations in mean plasma levels (P = < 0.001) were noted on POD1 (2549 ± 2632 pg/mL, n = 83), POD3 (1871 ± 1362 pg/mL, n = 77), POD7-13 (1788 ± 1403 pg/mL, n = 57), POD14-20 (1473 ± 738.8 pg/mL, n = 30), and POD21-27 (1681 ± 1375 pg/mL, n = 21). No significant differences were noted at POD 28-41. Higher values were noted in the HAL’s (vs LA) group, however, there were more rectal cancers in the former.

CONCLUSION

Elevated plasma eCIRP levels persist for a month post MICR for CRC (change from baseline, 77%-184%); highest values seen on POD1. The initial surge may be due to the acute inflammatory response while later elevations may be related to wound healing and remodeling. The higher levels noted in the HAL’s group (with greater IL and more rectal cases) suggest the extent of surgical trauma impacts eCIRP levels. Further investigations are needed.

Key Words: Effects of surgery; Plasma extracellular cold-inducible RNA-binding protein levels; Colorectal resection; Colorectal cancer; Angiogenesis

Core Tip: Our findings have substantiated that plasma collected during the second and third weeks post minimally invasive colorectal cancer resection (MICR) possesses the capacity to stimulate endothelial cell proliferation, invasion, and migration, which are essential prerequisites for neovascularization. This study, investigating perioperative plasma extracellular cold-inducible RNA-binding protein (eCIRP) levels in the context of MICR, evaluated six postoperative time points and unveiled that blood levels remain significantly elevated above preoperative baseline for a month after surgery. eCIRP and acts as a damage-associated molecular pattern molecule that promotes an inflammatory response (including TNF-α, IL-6 and HMGB production in macrophages, neutrophils, lymphocytes and dendritic cells. Elevated levels of eCIRP together with other elevated angiogenic proteins including T cell immunoglobulin and mucin domain-3 and monocyte chemo-attractant protein-1 may enhance macrophage activity and promote immune tolerance, potentially facilitating tumor growth and progression.

INTRODUCTION

While the 5-year relative survival rate for colorectal cancer (CRC) has been improving over the last two decades, metastatic CRC remains a deadly disease with only a 14% 5-year survival rate[1]. Surgical resection is the primary treatment modality for CRC, but there is increasing evidence that resection may alter the biology of residual tumor deposits[2,3]. As a response to the trauma caused during resection, the increase of pro-inflammatory and pro-angiogenic proteins that are associated wound healing and tissue remodeling may in fact be tumorigenic and promote growth in the immediate postoperative period[3-11]. Given that chemotherapy is typically held for at least 4 to 6 weeks postoperatively to allow for wound healing, this may be a dangerous period for cancer patients with residual tumor deposits.

Plasma from the 2^nd and 3^rd weeks after minimally invasive colorectal resection (MICR) for CRC has been shown to promote endothelial cell migration and invasion in vitro[3,6]. Further, there is considerable evidence that plasma levels of a sizable group of proteins with pro-angiogenic effects are elevated after MICR for 3-5 weeks. It is possible, though unproven, that these persistent changes might promote tumor angiogenesis and, thus tumor growth early after surgery, Research regarding blood composition after surgery continues.

Cold-inducible RNA-binding protein (CIRP) is a protein similar to a class of stress-induced RNA binding proteins. CIRP was discovered in the 1990s while studying cold stress adaptation in hibernating mammals and studies since have expanded our understanding of its function as regards stress adaptation in inflammation, sepsis, and cancer[12,13]. In the normal state, CIRP resides in the nucleus where it acts as an RNA chaperone that regulates RNA transcription and processing; it also impacts cell proliferation, cell survival, the circadian clock, and telomerase maintenance[12-16]. In stressful conditions, particularly those related to hypoxia such as hypothermia, sepsis, and hemorrhagic shock, CIRP moves to the cytoplasm where it regulates mRNA translation[15,17-19]. Further, during periods of stress a small amount of CIRP moves from the cytoplasm to the extracellular space where it becomes extracellular-CIRP (eCIRP) and acts as a damage-associated molecular pattern (DAMP) molecule that promotes an inflammatory response (including TNF-α, IL-6 and HMGB production)[12] in macrophages, neutrophils, lymphocytes and dendritic cells. It activates NF-κB pathways and necroptosis of macrophages via mitochondrial DNA damage[20]. The physiologic states that result in eCIRP generation involve low oxygen delivery and inflammation. Elevated eCIRP levels may promote macrophage function and induce immune tolerance that promotes tumor growth and progression. In healthy patients, plasma levels of eCIRP are undetectable. This study’s purpose was to measure plasma levels of eCIRP before MICR and for up to a month postoperatively in a population of CRC patients undergoing a “curative” operation.

MATERIALS AND METHODS

Study population

The study population was comprised of CRC patients who had undergone MICR and were enrolled in an Institutional Review Board-approved tissue and prospective data bank. Patients from the following institutions are included in this study: New York Presbyterian Hospital, New York (Columbia campus); Mount Sinai West (previously known as Roosevelt Hospital), New York; and the Ferguson Clinic, Grand Rapids, Michigan. The principal objective of the tissue banking effort was to evaluate the physiological, immunological, and oncological ramifications of major abdominal surgery. Blood specimens were collected preoperatively and at various postoperative time intervals from consenting CRC patients. The cohort chosen for the present study consisted exclusively of patients who underwent surgical intervention alone, without receiving novel pharmacological agents or other treatments in the perioperative period. Individuals who were immunosuppressed or had undergone chemotherapy in the preceding 30 days were excluded. Likewise, those who received perioperative blood transfusions or were subjected to emergency surgical procedures were also excluded. Data related to resection type, demographics, surgical procedure details, pathological findings, and early outcomes were extracted from the prospective database. Only patients for whom preoperative and multiple postoperative blood samples, including one from postoperative day (POD) 1 and at least one sample from POD 7 onwards, were available were eligible for the study.

Blood sampling and processing

The great majority of study patients had blood samples taken on POD 1 and 3. The late samples were taken at a wide variety of timepoints during the first 5 weeks after surgery and were aggregated into 7-day blocks (POD 7-13, 14-20, 21-27, 28-34) that were considered as individual time points for analysis. Because some patients refused late blood samples or had fewer postoperative office visits the “n”s for later time points are decreased.

Blood specimens were collected in heparin containing tubes and were processed within a 6-hour timeframe. Plasma was separated by centrifuging the samples at 450 G, and aliquots were stored at -80 °C until eCIRP analysis was carried out via enzyme-linked immunosorbent assay (ELISA) using a commercially sourced ELISA kit (R and D Systems, Minneapolis, United States), following the protocol stipulated by the manufacturer. eCIRP levels are reported in picograms per milliliter (pg/mL).

Statistical analysis

Data are presented as mean ± SD. Statistical comparisons were made using the Wilcoxon signed-rank test. The correlation between postoperative plasma eCIRP concentrations and variables such as incision size and surgery duration was assessed using Spearman’s rank correlation coefficient (rs). Differences in postoperative plasma eCIRP levels between the hand-assisted and laparoscopic MICR groups were examined using the Mann-Whitney U test. All statistical analyses were executed with SPSS version 15.0 software (SPSS, Inc., Chicago, IL). Due to the fluctuating sample sizes at the later time points (POD 7-13, POD 14-20, POD 21-27, and POD 28-34), a distinct preoperative results bar is incorporated for each time point in Figure 1.

Figure 1 Enzyme-linked immunosorbent assay determined preoperative and postoperative plasma levels of cold-inducible RNA-binding protein in patients with colorectal cancer. Extracellular cold-inducible RNA-binding protein (CIRP) levels are reported as mean ± SD. Preoperative (Preop) vs post-operative day (POD) 1 (n = 83, ^aP < 0.001); Preop vs POD 3 (n = 77, ^aP < 0.001); Preop vs POD 7-13 (n = 57, ^aP < 0.001); Preop vs POD 14 -20 (n = 30, ^aP < 0.001); Preop vs POD 21-27(n = 21, ^aP < 0.001); POD 28-41 time point (n = 19, ^bP = not significant). Statistical significance is expressed as ^aP < 0.001. POD: Post-operative day; Preop: Preoperative; eCIRP: Extracellular cold-inducible RNA-binding protein.

RESULTS

A cohort of 83 CRC patients [colon, 55 (66%); rectal, 28(34%)]; 46 males and 37 females; mean age of 65.02 ± 14.26 years) fulfilled the study inclusion criteria. The majority underwent laparoscopic-assisted (LA) procedures (58, 70%) while the remaining patients had a hand-assisted laparoscopic (HAL) resection (25, 31%). The most common operation was right colectomy, followed by sigmoid and low anterior (LAR) or anterior resection (AR) (Table 1). The mean incision length (IL) for the entire population was 7.8 ± 4.1 cm; for the LA cases it was 6.9 ± 4.1 cm and for the HAL cases it was 10.05 ± 2.93 cm. There were 2 conversions from LA to the HAL’s method and a total of 3 conversions to open surgical methods (LA to open, 1; HAL’s to open, 2). The mean duration of surgery was 336.2 ± 134.0 minutes, and the average hospital stay was 6.7 ± 3.43 days. There were no perioperative deaths or reoperations. There were 2 superficial SSI's (2.2%) but no deep or organ space SSI’s (anastomotic leaks or abdominal abscesses). Other complications noted were urinary tract infections (8), diarrhea (5), and ileus (3). The cancer stage distribution was as follows: Stage I (n = 25, 30%), Stage II (n = 26, 31%), Stage III (n = 29, 35%), and Stage IV (n = 3, 4%).

Table 1 Demographic and clinical characteristics of the study population, n (%)/mean ± SD.

Characteristic
Age, years	65.02 ± 14.26
Male	46 (55.0)
Female	37 (45.0)
Incision length (entire patient population), (cm)	7.8 ± 4.1
Incision length (lap procedure group), (cm)	6.9 ± 4.1
Incision length (hand procedure group), (cm)	10.1 ± 2.9
Operative time, (minutes)	336.2 ± 134.0
Length of stay, (days)	6.7 ± 3.43
Type of resection
Right	29 (35.0)
Sigmoid/recto-sigmoid (8/3)	11 (13.0)
LAR/AR (16/2)	18 (22.0)
Transverse	8 (10.0)
Total/subtotal (7/3)	10 (12.0)
Left	4 (5.0)
APR	3 (3.0)
Surgical method
Laparoscopic-assisted	58 (70)
Hand-assisted/hybrid laparoscopic	25 (30)

LAR: Low anterior resection; AR: Anterior resection; APR: Abdominoperineal resection.

The mean preoperative (preop) eCIRP concentration was 896.8 ± 757.0 pg/mL across the cohort. Markedly elevated mean plasma eCIRP levels (P < 0.0001) were observed at the following time points: POD1 (2549 ± 2632 pg/mL, n = 83), POD3 (1871 ± 1362 pg/mL, n = 77), POD7-13 (1788 ± 1403 pg/mL, n = 57), POD14-20 (1473 ± 738.8 pg/mL, n = 30), and POD21-27 (1681 ± 1375 pg/mL, n = 21, P < 0.001 for all). No significant difference was noted at the POD 28-41 time point (n = 19,P = 0.12) (Figure 1). The percentage increase in eCIRP from baseline at each time point was calculated and found to be as follows: 184% at POD1, 106 % at POD3, 100% at POD7-13, 77 % at POD14-20, 130% at POD21-27, and 24.3% at POD28-41.

To evaluate a possible relationship between IL and postoperative (postop) eCIRP levels, comparisons were made between the LA and HAL (with longer incisions) surgical method groups. Notably, higher mean eCIRP levels were observed in the HAL group for the first 5 postoperative time points (POD1- POD 21-27) and the difference reached statistical significance for the POD 1, POD 3, and POD 14-20 time points (P = 0.02-0.04). Percentage differences from mean eCIRP levels between the LA and HAL groups at each time point were as follows: 43.5% at POD1, 45.9% at POD3, 73.0% at POD7-13, 47.6% at POD14-20 and 53.8% at POD21-27.

No significant correlation was identified between eCIRP concentrations and case length at any post-operative time points. Also, there were no correlation was noted between cancer stage and preoperative eCIRP plasma levels.

DISCUSSION

This study assessed perioperative plasma levels of eCIRP in patients undergoing bowel resection for CRC. Significant and sizable elevations from the preoperative baseline level were noted to persist for the first month after surgery. Because most surgery related plasma protein changes are short lived, lasting hours to days, the eCIRP findings are notable. The percent change in mean values of eCIRP was prominent and ranged from 77%-186% for the first 5 postop time points. To what patient or procedure related factors are the plasma elevations related? The complication rates were low and there were no reoperations or major complications such as anastomotic leaks or abscesses. Therefore, there is no reason to suspect that the elevated plasma eCIRP levels were related to complications. Unfortunately, it is impossible to determine the cause of the persistent plasma increases from the data provided by this study. Possible contributing elements include: The cancer diagnosis, surgery related tissue trauma, anesthesia, and the wound healing process. It is not logical or likely that, after curative resection that the tumor could be responsible for the increases. Anesthesia related eCIRP effects, if contributory, would be short lived and would not account for elevations noted after the first 1-4 days. Surgical trauma itself certainly might influence the generation of eCIRP, however, wound healing, a process that extends for at least 4-6 weeks, may also contribute to the persistent elevations. In previous similar studies concerning more than 12 proteins whose postoperative plasma levels were found to be similarly elevated for 3-5 weeks after MICR, it was noted that the levels of these proteins in fluid from the wounds of these patients were 3 to 30 times higher than plasma levels at each time point. The increase in these protein levels within wounds facilitates the movement of macrophages to sites of inflammation and contributes to the process of angiogenesis. Angiogenesis is essential for wound healing, a prolonged process that typically spans a minimum of 6 to 8 weeks[21]. The authors plan to assess eCIRP levels in both wound fluid and plasma in a future study to determine if wound levels are increased.

Interestingly, when the LA and HALS group’s postop plasma eCIRP levels are compared the latter were higher at several time points. Might this difference be related to the increased abdominal wall trauma associated with gaining access to the abdomen in HALS procedures (mean IL 3.1 cm longer than LA group). It is logical to assume that the degree of eCIRP plasma elevation is related to the extent of surgical trauma which determines the scale and extent of the subsequent wound healing process. However, in addition to the abdominal wall access trauma, one must also take into consideration the intraabdominal trauma incurred during the operation. Since rectal resections require mobilization of the extra-peritoneal rectum and more extensive dissection, greater surgical trauma is usually incurred vs that associated with colectomy. In this study, the proportion of rectal resections (AR, LAR, and Abdominoperineal Resection) done using HAL’s method was 36% where as for the LA it was 21%. Therefore, it is not unreasonable to assume that the degree of surgical trauma was greater in the HAL’s group (longer incisions and more rectal cases). Having made this statement it should be noted that, as regards mean eCIRP levels at each postop time point, there were no significant differences noted between the rectal and colon cancer patients in this study although the rectal group mean levels were non significantly elevated at 3 time points. Also, importantly, no correlation was found between IL and postop eCIRP levels in this study. Thus, we cannot account for the differences noted between the HAL’s and LA groups. Perhaps in a larger study differences would be noted between rectal vs colon cases and a correlation between IL and plasma levels would be observed.

What is the clinical impact, if any, of this persistent increase in plasma eCIRP levels? As mentioned in the introduction, eCIRP is a DAMP molecule that can stimulate macrophages, dendritic cells, PMN’s, and lymphocytes to elaborate, among other mediators, TNF-α, IL-6 and HMGB and, by so doing, induce an inflammatory response. Since hypoxia, which is commonly found in tumors, stimulates eCIRP release, elevated eCIRP levels may promote macrophage function and lead to immune tolerance that supports tumor growth. Unfortunately, the clinical and oncologic impact, if any, of persistently elevated plasma eCIRP levels is unknown at this time. This study does not include any long term oncologic results and was not designed to address this issue.

As regards intracellular CIRP in the cancer setting, CIRP has been implicated in both tumor suppression and promotion[13]. Intracellular CIRP has been shown to slow cell growth by prolonging the G1 phase of the cell cycle[22]. In a model of rectal cancer, its levels in tumor tissue are upregulated in response to DNA damage to promote the translational efficiency of DNA damage response genes[23] whereas in endometrial and ovarian cancer, CIRP appears to slow proliferation[24,25]. CIRP is overexpressed in prostate, breast and colon cancer[26-28]. It promotes the transition from epithelial to mesenchymal cell lines and inhibits apoptosis via the ERK1/2 signaling pathway[16,29]. Given that most solid tumors develop a hypoxic core, it follows that CIRP will respond to these conditions and promote cellular growth and proliferation. CIRP may also be a marker for cancer progression as well; higher tumor levels of CIRP correlate with worse prognosis in oral squamous cell carcinoma, more aggressive tumor biology in pituitary adenoma and with the progression from DCIS to invasive breast cancer[30,31]. Unfortunately, in our cohort of patients undergoing elective MICR for CRC tumor expression of eCIRP was not determined. Also, as mentioned, presently, the ramifications of elevated eCIRP level in cancer patients post tumor resection are unknown.

There is a possibility that this plasma alteration might promote tumor growth in patients with residual tumor deposits after resection of the primary tumor. eCIRP’s long duration pattern of increased plasma levels after CRC similar to that noted for 12 other proteins previously found to be elevated for 3-5 weeks postop. These persistent increases are unique since the great majority of surgery related blood protein changes last, at most, 3-5 days. Almost all of the proteins with long duration increases have proangiogenic effects and it is hypothesized that they may promote tumor angiogenesis during the first month after MICR. Included in this group of proteins are VEGF, angiopoietin-2, soluble vascular adhesion molecule-1, monocyte chemotactic protein-1, chitinaise-3 Like protein, chemokine ligand 16, interleukin-8, Matrix metalloproteinase-2, Matrix metalloproteinase-3, Matrix metalloproteinase-7, Placental growth factor, Hepatocyte growth factor, Urokinase-type plasminogen activator-1 and Plasminogen activator inhibitor-1[3-11,32-34]. The endothelial cell culture studies, cited above, that showed that postop plasma from weeks 2 and 3 after MICR was associated with increased endothelial cell proliferation, migration and invasion (all important steps early in the process of angiogenesis), supports the general concept that postoperative plasma may be tumor promoting[3,6]. The oncologic significance of the eCIRP alterations remains uncertain, as previously mentioned.

As regards the just discussed proangiogenic long duration plasma protein increases, the first month after cancer resection may be a dangerous period since the systemic conditions may be conducive to the accelerated growth of residual cancer deposits. This fear has led to a search for anti-cancer agents that could safely be given during the early postoperative time frame. As regards eCIRP, assuming, without evidence presently, that elevated plasma eCIRP levels may contribute to the plasma’s protumor makeup after surgery it would make sense to consider and assess eCIRP targets/decoys that were developed for hemorrhagic shock and sepsis, including a neutralizing antibody and recombinant eCIRP that bind to receptors without activation[14,35-37]. To the author’s knowledge, these eCIRP targets have yet to be studied in cancer models.

Personalized cancer treatment is gaining significant attention in clinical practice, particularly in the context of CRC, as it acknowledges the distinct nature of each patient's cancer[38]. It is increasingly evident that the established and standardized treatment protocols for CRC may often prove ineffective, as individual differences in tumor characteristics, genetic factors, overall health status, and lifestyle choices can greatly affect treatment responses and outcomes. Personalized approaches to the treatment of CRC that are informed by elevated plasma levels of eCIRP remain a subject of ongoing investigation and have not yet been integrated into standard clinical protocols because there is little data presently. To determine the impact and potential import of postop sustained plasma eCIRP elevations in CRC patients it will be necessary to gather long term oncologic outcome data and also to increase the size of the CRC population being followed. In addition, the CRC population needs to be sub categorized as regards the extent and duration of the postop elevation in those patients whose levels rise after surgery. In order to have enough patients to determine if periop eCIRP levels correlate with or are associated with worse outcome a multi-center study might be needed. Unfortunately, this is beyond the capability of our lab and research team, at this moment. Nevertheless, the existing knowledge regarding the function of eCIRP in CRC indicates promising possibilities for the development of tailored treatment strategies in the future.

The overall health of a patient, which encompasses their nutritional condition, immune system functionality, and the existence of comorbidities, as well as any immune system impairments, can significantly influence the management of tumor growth and metastasis through the use of adjuvant therapies, even in cases where eCIRP levels are within the normal range. Poor nutritional status can hinder the healing process of wounds and recovery, potentially worsening the impact of increased plasma eCIRP-mediated inflammation and immune suppression, thereby necessitating more vigilant postoperative monitoring. Additionally, factors such as age, genetic predisposition, lifestyle choices including smoking and obesity, as well as existing medical conditions such as diabetes, cardiovascular disease, and chronic inflammatory diseases, must be assessed for patients exhibiting elevated eCIRP levels. These elements significantly impact the systemic inflammatory state in patients with elevated eCIRP and may necessitate adjustments in their therapeutic regimens to optimize treatment outcomes. The degree and nature of surgical resection, along with the pathophysiological factors associated with eCIRP, such as the presence of advanced tumor stages, tumor localization, and specific mutations like KRAS and BRAF, as well as the status of tumor microsatellite stability, should be taken into account alongside eCIRP levels when determining personalized treatment strategies.

Post-surgical interventions, including chemotherapy, radiotherapy, and immunotherapy, may require modifications due to the fact that these therapies typically elicit cellular stress responses, which could enhance the effects of eCIRP. Taking these factors into account, along with an understanding of the current eCIRP levels of the patents, clinicians can advance towards a more individualized strategy for CRC treatment, customizing approaches to align with the specific circumstances of each patient.

As regards eCIRP and cancer there is little data presently, thus we cannot recommend making treatment changes based on the height of the eCIRP elevation or the duration of the elevation. In order to determine the impact and potential import of postop sustained plasma eCIRP elevations in CRC it will be necessary to gather long term oncologic outcome data and also to increase the size of the CRC population being followed. In addition, the CRC population needs to be sub categorized as regards the extent and duration of the postop elevation in those patients whose levels rise after surgery. In order to have enough patients to determine if periop eCIRP levels correlate with or are associated with worse outcome a multi-center study might be needed. Unfortunately, this study was not designed to and is not capable of addressing these issues.

Authors would also like to suggest that the plasma eCIRP findings are best considered in light of the changes noted for the other 14 or so proteins whose plasma levels have been shown to also be elevated significantly over preop baseline for 3 to 5 weeks after CRC resection. All of these proteins play roles in angiogenesis, wound healing or some aspect of cancer growth. It is far more likely that the collective impact of these proangiogenic plasma changes might impact early postoperative tumor growth rather than the elevation of a single protein. Also, it is important to remember that the eCIRP and other protein changes noted postop are not related to the specific tumor types but to the surgical trauma and the subsequent wound healing. Certainly, the impact of these changes may vary from tumor to tumor, however, the general import is to create an environment conducive to angiogenesis, be in the wound or tumor deposit.

Significantly elevated plasma concentrations of eCIRP have been observed in patients diagnosed with CRC. Additionally, a higher expression of eCIRP in CRC tissues, as compared to adjacent normal tissues, has been noted, with these findings further validated by immunohistochemical analysis. Elevated eCIRP levels likely impact extracellular tissue levels which is inclusive of the tumor microenvironment. As regards the latter, we believe that because plasma eCIRP levels are elevated that eCIRP levels in the extracellular space will likewise be increased (we offer no supportive data in this report for this hypothesis). Further, increased eCIRP in the extracellular space is likely to be pro-tumorigenic in that eCIRP has been shown to impact cell differentiation, proliferation and growth. Further studies are needed to explore these concepts.

This study has several important limitations. The overall size of the study is limited and, therefore, larger studies are needed. In addition, a variety of different large bowel resections were considered and the surgical trauma associated with each varies which is not ideal. Also, because, after hospital discharge, it was not possible to restrict late blood sampling to set days, we bundled samples gathered over 7 days periods which is unfortunate. Further, the ‘N” for the late time points is notably less than the starting number; patient refusal and limited postop office visits are the reasons for this attrition. Also, tumor expression of CIRP was not assessed: It would have been useful to know whether the tumors removed overexpressed CIRP in relation to normal colonic mucosa. Thankfully, a study underway will address this deficiency. The final criticism is that we have no oncologic outcome data.

CONCLUSION

In patients undergoing minimally invasive colectomies for CRC, levels of eCIRP postoperatively have been demonstrated to be persistently and impressively elevated for at least one month. While the cause of these elevations cannot be determined from the current study, the author’s hypothesize that these long duration increases are related to wound healing and tissue remodeling. Together with MCP-1, CHI3 L-1 and IL8, which have been previously shown to be persistently elevated postoperatively, eCIRP may promote macrophage recruitment and the growth of residual deposits early postoperatively. eCIRP may be a future target for anti-cancer therapies in this vulnerable period.