Retrospective Study
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Surg. Jun 27, 2016; 8(6): 452-460
Published online Jun 27, 2016. doi: 10.4240/wjgs.v8.i6.452
Critical appraisal of laparoscopic vs open rectal cancer surgery
Winson Jianhong Tan, Min Hoe Chew, Angela Renayanti Dharmawan, Manraj Singh, Sanchalika Acharyya, Carol Tien Tau Loi, Choong Leong Tang
Winson Jianhong Tan, Min Hoe Chew, Angela Renayanti Dharmawan, Manraj Singh, Carol Tien Tau Loi, Choong Leong Tang, Department of Colorectal Surgery, Singapore General Hospital, Singapore 169856, Singapore
Sanchalika Acharyya, Centre for Qualitative Medicine, DUKE NUS Graduate Medical School, Singapore 169857, Singapore
Author contributions: Tan WJ, Chew MH, Dharmawan AR, Singh M, Acharrya S, Loi CTT and Tang CL designed the study; Tan WJ, Dharmawan AR, Singh M and Loi CTT collected data for the study; Tan WJ, Chew MH, Dharmawan AR, Singh M, Acharrya S and Tang CL performed statistical analysis for the study; Tan WJ, Chew MH, Dharmawan AR, Singh M, Acharrya S, Loi CTT and Tang CL drafted the manuscript and were involved in the final approval of the manuscript.
Institutional review board statement: This study was approved by the Singhealth Institutional Review Board.
Informed consent statement: Waiver granted by Institutional Review Board in view of Retrospective nature of study.
Conflict-of-interest statement: There are no conflicts of interest.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Min Hoe Chew, Consultant, MBBS, M. Med, FRCS, Department of Colorectal Surgery, Singapore General Hospital, 20 College Road, Academia, Singapore 169856, Singapore. chew.min.hoe@sgh.com.sg
Telephone: +65-63214677 Fax: +65-62273787
Received: February 2, 2016
Peer-review started: February 2, 2016
First decision: March 1, 2016
Revised: March 5, 2016
Accepted: March 24, 2016
Article in press: March 25, 2016
Published online: June 27, 2016

Abstract

AIM: To evaluate the long-term clinical and oncological outcomes of laparoscopic rectal resection (LRR) and the impact of conversion in patients with rectal cancer.

METHODS: An analysis was performed on a prospective database of 633 consecutive patients with rectal cancer who underwent surgical resection. Patients were compared in three groups: Open surgery (OP), laparoscopic surgery, and converted laparoscopic surgery. Short-term outcomes, long-term outcomes, and survival analysis were compared.

RESULTS: Among 633 patients studied, 200 patients had successful laparoscopic resections with a conversion rate of 11.1% (25 out of 225). Factors predictive of survival on univariate analysis include the laparoscopic approach (P = 0.016), together with factors such as age, ASA status, stage of disease, tumor grade, presence of perineural invasion and vascular emboli, circumferential resection margin < 2 mm, and postoperative adjuvant chemotherapy. The survival benefit of laparoscopic surgery was no longer significant on multivariate analysis (P = 0.148). Neither 5-year overall survival (70.5% vs 61.8%, P = 0.217) nor 5-year cancer free survival (64.3% vs 66.6%, P = 0.854) were significantly different between the laparoscopic group and the converted group.

CONCLUSION: LRR has equivalent long-term oncologic outcomes when compared to OP. Laparoscopic conversion does not confer a worse prognosis.

Key Words: Rectal cancer, Laparoscopic, Outcomes, Conversion, Prognosis

Core tip: Laparoscopic rectal resection (LRR) remains controversial in view of concerns over its long term oncological outcome and the adverse impact conversion may have on survival. Our retrospective study has demonstrated that LRR has equivalent long-term oncologic outcomes when compared to open surgery. Conversion was also found not to confer a worse prognosis.



INTRODUCTION

Surgical management for rectal cancer remains challenging. With the advent of total mesorectal excision (TME) in rectal cancer surgery, local recurrence rates have improved significantly and there is an increasing rate of sphincter-saving surgery when technically and oncologically feasible. However, despite the use of pre- or post-operative adjuvant chemoradiotherapy, local and distant tumor recurrence remains a concern.

While laparoscopic colectomy has established its oncologic equivalence compared to open surgery (OP) in colon cancer, laparoscopic rectal resection (LRR) for rectal cancer remains controversial. Although LRR has been shown to confer short-term benefits, in terms of blood loss, length of stay, recovery of bowel function, and cosmesis, concerns about the long-term oncologic outcomes persists[1-5]. The necessity for a TME creates a more difficult learning curve for LRR compared to a laparoscopic colectomy. There is also the need to achieve a balance between sphincter preservation without compromising the adequacy of the distal resection margin[6]. These challenges induce a higher rate of conversion compared to colonic resection[2] and a recent Cochrane review has noted that conversion rates in LRR can be as high as 35%[7]. This is an important concern as it has been suggested that conversion to OP after attempted LRR not only has higher morbidity, but may also adversely affect long-term oncologic outcomes[2,8-11]. Several publications have attempted to address this issue but the study populations often consisted of a mixture of patients with colon and rectal cancer[12-14]. This is suboptimal as the prognosis and recurrence pattern of colon and rectal cancer are distinctly different. There are few publications that address the long-term outcomes of laparoscopic conversion specifically in the context of rectal cancer[10,15,16].

Therefore, the objective of this study is to evaluate the long-term clinical and oncological outcomes of LRR as well as the impact of laparoscopic conversion on the long-term oncological outcomes of patients with rectal cancer.

MATERIALS AND METHODS

An analysis of a prospectively maintained database of 633 consecutive patients with rectal cancer who underwent surgical resection from January 2005 to December 2009 in the Department of Colorectal Surgery at Singapore General Hospital was performed. Patients who presented with recurrent cancer, Inflammatory Bowel Disease, Familial Adenomatous Polyposis, or other polyposis syndromes were excluded. Data on patient demographics, pre-operative, operative, and post-operative course were collected prospectively and maintained in a database by a research assistant.

All cases were performed by consultant surgeons within the department. The decision for laparoscopic or open approach was left to the discretion of the individual surgeon.

For the laparoscopic approach, we preferred the medial approach with early mobilization, ligation and division of the inferior mesenteric artery at its origin after the ureter has been identified. The inferior mesenteric vein was ligated and divided at the inferior border of the pancreas. This was followed by mobilization of the left colon from the lateral sidewall, with mobilization of the splenic flexure if deemed necessary to achieve a tension free anastomosis. Total meso-rectal excision or wide meso-rectal excision up to at least 2 cm distal to the tumor was performed for all cases when feasible. Distal transection was performed using articulating staplers. The specimen is exteriorized via extension of the port sites with proximal transection performed extra-corporeally. Pneumoperitoneum is then re-established and intra-corporeal circular stapled anastomosis performed under direct vision.

OP was performed via a midline laparotomy or left iliac fossa incision as described in a previous publication[17].

Patients were compared in three groups: OP, laparoscopic surgery (LS), and converted laparoscopic surgery (CON) with their definitions as follows: (1) OP: Completion of surgical resection and anastomosis via midline laparotomy or left iliac fossa incision; (2) LS: Surgery accomplished using the laparoscopic technique as described above. Patients analyzed under the LS group included patients who underwent laparoscopic-assisted surgery as described in a previous publication by our department[18]. These were patients who had vascular ligation and the majority of bowel mobilization was accomplished intra-corporeally via the laparoscopic approach with the following modifications: (a) extension of one port site wound or the utilization of a new wound to complete colonic mobilization and bowel transection for reasons such as the presence of adhesions, excessive tumor fixation, or uncertain tumor location; (b) extracorporeal rectal anastomosis due to technical difficulties such as a narrow pelvis, bulky tumor, or defective equipment; and (c) extension of wounds to repair the anastomosis due to leaks on testing after completion of a pure laparoscopic resection; (3) CON: The laparoscopic approach is aborted after insertion of ports and initial bowel mobilization. This can be due to the presence of dense adhesions, undiagnosed tumor invasion of surrounding organs, or trouble-shooting complications such as uncontrolled bleeding, bowel perforation, or injury of adjacent viscera such as ureters or small bowel. Conversion is also defined if the anastomosis requires a complete takedown and revision.

Pre-operative staging

All cases were evaluated preoperatively by plain chest radiograph/computed tomography (CT) of the thorax and CT of the abdomen and pelvis. T-staging with an endo-rectal ultrasound was performed pre-operatively in clinical T1 and T2, mid and low rectal tumors. Magnetic resonance imaging (MRI) of the pelvis was performed for all lower rectum tumors. Upper rectum is defined as 11-15 cm, middle rectum as 6-10 cm, and lower rectum as 0-5 cm from the anal verge. These measurements were recorded by the consultant surgeon after digital rectal examination and endoscopy. Disease staging according to the American Joint Committee Cancer (AJCC) Cancer Staging Manual 7th Edition was adopted[19].

Neoadjuvant/adjuvant therapy

In our institution, a selective neoadjuvant chemoradiation policy is adopted based on data from previous publications that have consistently shown low local recurrence rates with oncologically adequate surgery alone[20-22]. If sphincter preservation with good margins can be performed after initial evaluation, neoadjuvant treatment is usually not routinely recommended in our local population. Neoadjuvant treatment is mainly performed in patients who present with a threatened circumferential resection margin, defined as within 2 mm of the circumferential resection margin based on pre-operative staging.

The neoadjuvant regimen consisted of long-course preoperative radiotherapy (45-50 Gy in 25-28 daily fractions over 5 wk) combined with 5-fluorouracil or oral capecitabine. Patients proceeded with surgical resection 6 to 8 wk after completion of neoadjuvant chemoradiotherapy. Decision for adjuvant chemotherapy was decided after discussion at a multi-disciplinary tumor board meeting.

Perioperative care for all patients was standardized using existing clinical care pathways.

Follow-up details

Post-operatively, the patients were followed-up at three monthly intervals for the first two years, six monthly for the next three years, and then yearly thereafter. At each consultation, carcinoembryonic antigen (CEA) levels were measured and full history and physical examination (including digital rectal examination) were performed. Colonoscopy was performed within six months of surgery if initial complete evaluation was not possible pre-operatively due to tumor obstruction or stenosis. Those who had an initial complete evaluation underwent colonoscopy at the first year follow up, and again at 3-yearly intervals post-operatively. Patients with suspicious symptoms and signs of rising CEA trend on follow-up will be evaluated earlier with colonoscopy and/or radiological imaging (including computerized tomography of the chest, abdomen, and pelvis, bone scan, and positron emission tomography scans if applicable).

Local recurrence was defined as the first clinical, radiologic, and/or pathologic evident tumor of the same histological type, within the true pelvis, at the anastomosis or in the region of the anastomosis. Distant recurrence was defined as similar evidence of spread outside the primary tumor at sites including but not limited to the liver, lungs, bone, brain, and para-aortic region. Patients who were first diagnosed with local recurrence but later developed distant metastasis were classified under the local recurrence group. Mortality data and the cause of death were obtained from the Singapore Cancer Registry.

Short-term outcomes assessed included wound infections, post-operative ileus, anastomotic leaks, pneumonia, peri-operative cardiac events, duration of hospitalization, and 30-d mortality.

Long-term outcomes assessed included the occurrence of intestinal obstruction, incisional hernias, and the oncologic outcomes of local/distal recurrence.

Survival analysis was performed via the comparison of progression free survival and overall survival (OS).

Statistical analysis

All statistical analysis was performed by a qualified biostatistician. Demographic and clinicopathological characteristics of the patients were compared across the 3 groups using χ2 and t tests for categorical and continuous variables respectively. Distribution of selected short- and long-term outcomes among the patients undergoing surgery was compared using Fisher’s exact test. Comparison of the median duration of hospitalization was performed using the Kruskal-Wallis nonparametric test as it deviates from the Normality assumption.

OS was calculated from the date of diagnosis to the date of death or last follow-up. Cancer-free survival (CFS) was calculated from the date of diagnosis to the date of disease progression (local or distant relapse) or last follow-up. The 5-year OS and CFS were estimated using Kaplan Meier method and the survival curves were compared using log-rank tests. Multivariate Cox proportional hazards models, using variables found to be significant on univariate analysis, were used to estimate hazard ratios with their 95%CI. A significance level of 0.05 was chosen throughout. All analyses were performed using R 3.1.1 (2014, Vienna, Austria).

RESULTS

Six hundred and thirty-three patients underwent surgical resection for primary rectal cancers during the study duration. The demographic characteristics of the study population are illustrated in Table 1. Two hundred and twenty-five patients (35.5%) underwent attempted laparoscopic resection of the rectal tumor. Among these, 200 patients had successful laparoscopic resection with 77 patients (34.2%) requiring a laparoscopic-assisted approach, predominantly due to anatomic difficulties during the LS (50 out of 77 patients). Patients in the OP group were older [66 years old (OP) vs 59 years (LS), P < 0.001] and had slightly higher proportion of patients with ASA 3 and 4 [13.5% (OP) vs 10% (LS), P = 0.002]. The proportion of patients who underwent neoadjuvant chemotherapy and radiotherapy was also higher among patients in the OP group compared to LS group [3.4% vs 2.5% (chemotherapy) and 2.9% vs 1.5% (radiotherapy) respectively]. The laparoscopic conversion rate was 11.1% (25 out of 225) with the reasons for conversion illustrated in Table 2. All conversions to OP were unplanned pre-operatively. Close to half (12 out of 25) of the patients were converted due to the presence of excessive adhesions. The oncologic and peri-operative outcomes of the entire study cohort are presented in Table 3. Duration of surgery was significantly longer in the LS compared to the OP group [162 min (LS) vs 119 min (OP), P < 0.001]. Length of hospitalization was shorter in the LS group compared to OP group (7 d vs 8 d, P < 0.001).

Table 1 Demographic characteristics of study cohort.
VariablesLap (%) n = 200Converted (%) n = 25Open (%) n = 408P value
GenderMale128 (64)15 (60)243 (60)0.570
Female72 (36)10 (40)165 (40)
Median age (yr)596366< 0.001
Ethnic groupChinese172 (86)22 (88)352 (86.3)0.368
Malay9 (4.5)019 (4.7)
Indian4 (2)2 (8)18 (4.4)
Others15 (7.5)1 (4)19 (4.7)
ASA175 (37.5)4 (16)84 (20.6)0.002
2105 (52.5)20 (80)267 (65.4)
320 (10)1 (4)55 (13.5)
4002 (0.4)
Location of tumorLower rectum68 (34)8 (32)131 (32.1)0.381
Middle rectum90 (45)10 (40)212 (52)
Upper rectum42 (21)7 (28)65 (15.9)
Type of surgeryHAR30 (15)4 (16)24 (5.9)0.067
LAR (w/stoma)27 (13.5)4 (16)82 (20.1)
LAR (w/o stoma)32 (16)5 (20)76 (18.6)
ULAR98 (49)12 (48)193 (47.3)
APR13 (6.5)033 (8.1)
Neo-adjuvant therapy statusChemo-therapy5 (2.5)014 (3.4)< 0.001
Radio-therapy3 (1.5)012 (2.9)< 0.001
Adjuvant therapy statusChemo-therapy65 (32.5)15 (60)134 (32.8)0.071
Radio-therapy28 (14)7 (28)82 (20.1)0.271
Table 2 Reasons for laparoscopic conversion to open surgery.
Reason for conversionNo. of patients (% within converted patients)
Excessive adhesions12 (48)
Advanced tumor or excessive tumor fixation3 (12)
Difficult anatomy3 (12)
Intraoperative complications (e.g., bleeding, ureteric/urinary tract injury, bowel perforation/injury)4 (16)
Intolerant of tilt and pneumoperitoneum3 (12)
Table 3 Oncologic characteristics and perioperative outcomes of study cohort.
VariablesLap (%) n = 200Converted (%) n = 25Open (%) n = 408P value
Tumor gradeWell-differentiated20 (10)3 (12)38 (9.3)0.339
Mod-differentiated173 (86.5)21 (84)349 (85.6)
Poorly-differentiated7 (3.5)1 (4)21 (5.1)
Median lesion size (cm)3.94.14.30.275
T stageT118 (9)3 (12)23 (5.6)0.151
T243 (21.5)4 (16)73 (17.9)
T3126 (63)9 (36)265 (65)
T413 (6.5)9 (36)47 (11.5)
Nodal statusN095 (47.5)10 (40)188 (46.1)0.77
N+105 (52.5)15 (60)320 (53.9)
TNM stageStage I47 (23.5)3 (12)69 (16.9)0.086
Stage II51 (25.5)4 (16)111 (27.2)
Stage III75 (37.5)9 (36)162 (39.7)
Stage IV27 (13.5)9 (36)66 (16.2)
Perineural invasion+38 (19)8 (32)90 (22.1)0.652
-162 (81)17 (68)318 (77.9)
Vascular invasion+61 (30.5)11 (44)135 (33.1)0.617
-139 (69.5)14 (56)275 (66.9)
Median lymph nodes harvested (range)14 (4-90)15 (4-55)14 (3-56)0.447
Proximal margin (cm)9.9 (0-30)10 (2-22)12 (0-39)0.004
Distal margin (cm)2.1 (1-15)1.8 (1-15)2 (1-14)0.55
CRM < 2 mm29 (14.5)5 (20)75 (18.4)0.494
Median duration of surgery (min)162147119< 0.001
Length of hospitalization7 (3-159)7 (5-16)8 (3-78)< 0.001

Comparison of short-term and long-term outcomes between the 3 groups is illustrated in Table 4 and there were no significant differences between the 3 groups. The 5-year CFS and OS for the 3 group of patients is illustrated in Figure 1. Results of the univariate and multivariate analyses for predictive factors of survival are summarized in Table 5. Factors found to be predictive of survival on univariate analysis include the laparoscopic approach (P = 0.016), together with factors such as age, ASA status, stage of disease, tumor grade, presence of perineural invasion and vascular emboli, CRM < 2 mm, and postoperative adjuvant chemotherapy. The survival benefit of LS was no longer significant on multivariate analysis (P = 0.148) and only age, stage of disease, tumor grade, and CRM < 2 mm remained significant. After excluding open cases, neither 5-year OS (70.5% vs 61.8%, P = 0.217) nor 5-year CFS (64.3% vs 66.6%, P = 0.854) were significantly different between the laparoscopic group and the converted group.

Figure 1
Figure 1 Kaplan-Meier curves comparing the three surgery groups for cancer free survival and overall survival. 1Cancer free survival and overall survival is compared.
Table 4 Distribution of long-term and short-term outcomes across three surgery groups.
Laparoscopic surgery n = 200Converted surgery n = 25Open surgery n = 408P value
No. of patients (%)No. of patients (%)No. of patients (%)
Short-term outcomes
Anastomotic leaks13 (6.5)0 (0)17 (4.2)0.233
Wound complications8 (4)2 (8.0)31 (7.6)0.227
Bleeding complications5 (2.5)1 (4.0)9 (2.2)0.840
Ileus3 (1.5)2 (8.0)18 (4.4)0.097
Pneumonia1 (0.5)0 (0)8 (2)0.298
Cardiac events7 (3.5)2 (8)17 (4.2)0.562
30 d mortality2 (1)0 (0)8 (2.0)0.545
Long-term
Intestinal obstruction23 (11.5)5 (20)59 (14.5)0.396
Incisional hernia9 (4.5)1 (4)33 (8.1)0.218
Local recurrence9 (4.5)1 (4.0)36 (8.8)0.126
Distant recurrence45 (22.5)6 (24)106 (26)0.644
Table 5 Prognostic factors of overall survival: Univariate and multivariate analysis.
Variable5 yr overall survival (%)Univariate P valueOverall survival HR (95%CI)Multivariate P value
Age ≥ 65 vs < 6550.9 vs 68.3< 0.00111.4557 (1.083-1.9568)0.0032
Gender (male vs female)60.6 vs 600.921--
Lap vs converted vs open70.5 vs 61.8 vs 52.70.0161-0.148
ASA 1/2 vs 3/462.6 vs 45.70.0161-0.131
NeoadjChemo (yes vs no)59.5 vs 60.40.36--
NeoadjRT (yes vs no)66.7 vs 60.20.654--
AdjChemo (yes vs no)40.8 vs 70.5< 0.0011-0.06
AdjRT (yes vs no)53.2 vs 62.30.206--
TNM stage (I-IV)< 0.0011< 0.0012
Stage I77.2Reference
Stage II73.81.04 (0.58-1.84)0.907
Stage III60.31.52 (0.89-2.58)0.124
Stage IV13.95.80 (3.26-10.33)< 0.001
Tumor grade0.00210.0152
Well differentiated75Reference
Moderately differentiated60.12.10 (1.00-4.40)0.049
Poorly differentiated39.11.18 (0.54-2.54)0.682
CRM < 2 mm vs > 2 mm40.1 vs 63.5< 0.00111.66 (1.19-2.32)0.0032
No. of lymph nodes ≥ 12 vs < 1262.2 vs 56.10.08--
Perineural invasion36.2 vs 67.3< 0.0011-0.276
Vascular emboli46.2 vs 68.5< 0.0011-0.14
Clinical symptoms of obstruction at presentation (yes vs no)35.3 vs 64.6< 0.00111.95 (1.39-2.74)< 0.0012
DISCUSSION

In our study, the 5-year OS was 70.5% in the LS group vs 52.7% in the OP group. While the laparoscopic technique appeared to confer survival benefit on univariate analysis, this is likely attributed to the inherent selection bias in the study as patients chosen for OP tend to be older and with more advanced ASA status. As such, the differences in survival were no longer significant when subjected to multivariate analysis. There was also no difference in the local or systemic recurrence rates between all groups. These results are in line with several published studies comparing at least 5-year survival data of laparoscopic against open rectal resections (Table 6)[4,6,23-30]. They are also congruent with the findings of two recent randomized trials comparing laparoscopic with open resection in rectal cancer[31,32]. However, conflicting results were seen when pathologic adequacy of surgical resection was used as the outcome of interest. Both the ALaCaRT and the ACOSOG Z6051 trial failed to demonstrate non inferiority in terms of oncologic adequacy of resection when LS was compared to OP[33,34]. These results have cast doubt on the role of LS in rectal cancer. Hopefully, the long term follow up data of the above two studies will help shed light on the contentious issue of LS in rectal cancer.

Table 6 Summary of studies reporting at least 5 year survival outcomes of laparoscopic vs open rectal resection.
Ref.Type of studyNo. of patients with rectal cancer5 yr overall survivalRemarks
Lujan et al[4]Randomized Controlled Trial204 (103 open, 101 lap)75.3% (open) vs 72.1% (lap) P = 0.980Middle and low rectal cancers only
Green et al[26], (MRC CLASICC trial)Randomized Controlled Trial381 (128 open, 253 lap)52.9% (open) vs 60.3% (lap) P = 0.132
Ng et al[29]Pooled Analysis of 3 RCT278 (142 open, 136 lap)61.1% (open) vs 63.0% (lap) P = 0.50510 yr overall survival
Laurent et al[6]Retrospective Comparative Study471 (233 open, 239 lap)79% (open) vs 82% (lap) P = 0.52Cancer free survival main outcome measure
Day et al[25]Retrospective222 (133 open, 89 lap)58% (open) vs 75% (lap) P = 0.014Laparoscopic group had better survival on multivariate analysis as well
Baik et al[24]Case-matched Controlled Analysis162 (108 open, 54 lap)88.5% (open) vs 90.8% (lap) P = 0.261
Li et al[28]Retrospective238 (123 open, 113 lap)78.9% (open) vs 77.9% (lap) P = 0.913Middle and low rectal cancers only
Lim et al[21]Retrospective191 (91 open, 100 lap)72.6% (open) vs 74.7% (lap) P = 0.54
Zhong et al[30]Retrospective514 (238 open, 186 lap)61.3% (open) vs 69.4% (lap) P = 0.067
Agha et al[23]Retrospective225 (all laparoscopic)50.5% (lap)10 yr overall survival

Studies assessing the impact of conversion on oncological outcomes have shown conflicting results and a recent meta-analysis found that conversion was associated with an adverse long-term oncological outcome[35]. Postulated mechanisms include the increased inflammatory response associated with conversion and requirement for blood transfusion in converted cases that may subsequently increase recurrence risks[36]. However, both colonic and rectal resections were included in the above meta-analysis, with the former constituting the majority of the pooled patient population. Subset analysis of laparoscopic conversion in our study cohort revealed that conversion did not have an adverse impact on long-term oncologic outcomes in rectal cancer. Several studies have reported the impact of conversion in LRR for cancer[6,8,10,15,16,37]. While most studies had similar findings to ours, Rottoli et al[15] concluded that conversion could have a negative impact on long-term overall recurrence rate. It is noted in this study, however, that 8 out of 26 (30.7%) patients were converted due to advanced tumors and may thus explain poorer survival. In contrast, the majority of our conversions were due to adhesions (> 50%) and not advanced disease (12%) (Table 2). Thus it was not surprising that laparoscopic conversion had no impact on long-term oncologic outcomes.

The major limitation of our study lies in its retrospective nature which makes it susceptible to the effects of confounding and selection bias. While formal matching of the various groups of the study cohort was not performed due to numerical limitations, majority of the clinical demographics and tumor pathological characteristics between groups were similar, allowing for meaningful comparison. While we acknowledge the antecedent limitations of the retrospective nature of our study, it does have several strengths. Firstly, to the best of our knowledge, this is the largest study cohort evaluating the long-term outcomes (5-year survival data) of surgical resection in rectal cancers. Unlike other studies, conversions were clearly defined which facilitates comparison of findings in other institutions. Thus, we believe that this study will add value to the available literature on surgical resection for rectal cancer.

LRR is safe and has equivalent long-term oncologic outcomes when compared to OP. Laparoscopic conversion does not appear to confer an adverse outcome. Further evaluation of long-term data from updated randomized studies comprising of larger number of patients may be required to discern more differences.

COMMENTS
Background

Laparoscopic resection for rectal cancer remains controversial. The authors evaluate the long-term clinical and oncological outcomes of laparoscopic rectal resection and the impact of conversion in patients with rectal cancer.

Research frontiers

The impact of laparoscopic conversion in rectal cancer remains unknown. This study assesses the impact of laparoscopic conversion in patients with rectal cancer.

Innovations and breakthroughs

Laparoscopic surgery for rectal cancer has equivalent long term oncological outcomes when compared with open surgery. Conversion in rectal cancer was not shown to be associated with an adverse outcome.

Applications

Laparoscopic resection for rectal cancer is feasible with no adverse impact on long term oncological outcomes even in the event of conversion.

Terminology

LRR: Laparoscopic rectal resection; OP: Open surgery; LS: Laparoscopic surgery; CON: Converted laparoscopic surgery.

Peer-review

The paper describes a single-center experience on laparosocpic surgery for rectal cancer. It is well written and references are updated.

Footnotes

P- Reviewer: Carboni F, Sinagra E S- Editor: Ji FF L- Editor: A E- Editor: Wu HL

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