Operative blood loss and use of blood products after full robotic and conventional low anterior resection with total mesorectal excision for treatment of rectal cancer

Previous studies have already supported the feasibility and oncologic safety of robotic LAR, although their results were limited by the small number of cases representing the early phase of the learning curve [13]. Since the first reports of robot-assisted rectal cancer surgery, the advantages of the robotic approach were focused on better early postoperative outcomes compared with conventional open analogue procedures, including earlier recovery, less postoperative pain due to smaller incisions, and a shorter postoperative hospital stay [14]. Blood loss has not been investigated in depth until now, in spite of immunosuppression, an untoward effect of allogenic transfusion, which has been postulated to result in decreased tumor surveillance and detrimental outcome. In 1982, Burrows and Tartter first linked perioperative allogenic blood transfusion to the prognosis of colorectal malignancy [15]. More recently (2006), a Cochrane Collaboration Review [16] confirmed in an updated meta-analysis the hypothesis that perioperative blood transfusions have a detrimental effect on the recurrence of curable colorectal cancers; the authors concluded that carefully restricted indications for allogenic blood transfusion are necessary in this clinical setting, although a causal relationship cannot be claimed, due to the heterogeneity detected and the not yet completely defined impact of surgical technique [17].

To date, there is no uniform consensus on the relative blood loss when patients undergo low anterior resection for cancer using an open or a robotic approach, and that is true also for laparoscopic low anterior resection. While some studies found that EBL during minimally invasive colorectal resections was significantly lower than during analogue open procedures [18‐21], others found the loss to be comparable [22, 23]. A possible reason could be the fact that most of these studies used EBL as the sole measure of blood loss during surgery, a parameter previously reported to be an inconsistent estimate of real blood loss [24, 25]. We used two additional measures to precisely define the blood loss related to surgery: postoperative hemoglobin level drop and overall use of blood products. Hemoglobin drop was much less in the robotic group, thus confirming a significant superiority of robot-assisted LAR in this clinical setting, whereas overall use of blood products showed a trend in favor of the R-LAR patients (12 vs. 1 units of packed red blood cells, P = 0.051). In both univariate and multivariate analyses, conventional open surgery was confirmed as the sole variable significantly associated with blood loss; moreover, it was confirmed as a prognosticator of blood loss when a preoperative clinical predictive model was built.

Interestingly, oncology outcomes were also in favor of the robotic group, as witnessed by a higher number of harvested lymph nodes and a higher extent of free distal margin in the surgical specimens, thus confirming previous observations of our and other groups [13]. These results have been obtained while maintaining a comparable rate of surgical peroperative complications and a much lower hospital stay in the R-LAR group.

There are several limitations of this study that deserve some mentions. First, this is not a randomized trial, and therefore it could suffer from the typical limitations of observational-descriptive studies. Nevertheless, this is the first study specifically addressing the topic of blood loss and use of blood products in robotic low anterior resection, by means of a comparison between two quite large series of case-matched patients undergoing the same oncology procedure (low anterior resection) by the same surgical team, using a conventional open and a full robotic approach in the same institution and in a consecutive period of 6 years (three per group). During this study period, practice of care, perioperative management, and, in particular, transfusional policies did not change in our institution.

Another point to be noted is matching, since a potentially important difference between the groups was the higher prevalence of ASA class 3 in the open surgery one. This could reflect possible changes in the attitude and judging of attending anesthesiologists, to whom patients’ ASA classification is routinely given, as the anesthesiology team differed during the study periods, unlike the surgical one. However, our multivariate analysis is adjusted for all patients and tumor characteristics of prognostic relevance, and it excluded ASA class as a variable possibly associated with blood loss.

The higher prevalence in the robotic arm of patients who underwent preoperative neoadjuvant treatment (73.5% vs. 52,4%, P = 0.013) is worth of further comment. Use of preoperative neoadjuvant chemo-radiation therapy became a standard option in our institution for locally advanced disease, preoperatively staged as any T, N positive or ≥ T3, any N, and this explains the higher prevalence of these cases in the second group (R-LAR), treated since 2007. A large previous trial, using a conventional open approach, reported that patients randomly assigned to preoperative radiation therapy lost more blood than those assigned to surgery alone (median blood loss 1,000 vs. 900 mL; P < 0.001) [26]. Our data do not confirm these results: firstly, no differences were detected between preoperative chemo-radiation and immediate surgery groups in terms of EBL; moreover, median EBL for open surgery was only 100 mL, and zero mL for the robotic group. These findings probably reflect a significant and general improvement in surgical techniques, since these reference surgical data come from a national study concluded in the late 1990s; moreover, they underline the superiority of the robotic technique applied to LAR also in “difficult” patients, such as those who underwent chemo-radiation neoadjuvant treatment. With respect to this issue, it is noteworthy to point out that we always applied—in both groups—one or more sheets of regenerated oxidized cellulose (Tabotamp^® or Tabotamp Fibrillar^®, Johnson & Johnson, Pratica di Mare, Rome, Italy) in case of residual bleeding after mesorectal excision, usually coming from small sacral and coccygeal interrupted venules. This is a fairly common finding in pretreated rectal cancer patients, where the presacral Waldayer’s fascia is frequently involved in a thick, fibrous post-radiation tissue, and sacro-coccygeal venules cannot be easily identified.