Robotic Approach is Associated With a Lower Conversion Rate Compared to Laparoscopic Approach for Patients Undergoing Colectomy for T4b Colon Cancer. An Analysis of the National Cancer Database

The National Cancer Database

The NCDB includes data on more than 70% of patients with a new cancer diagnosis from over 1500 hospitals across the United States. Through the joint efforts of the American Cancer Society and the American College of Surgeons, de-identified data on the demographics, clinicopathological characteristics as well as perioperative outcomes and overall survival are collected and is made available to researchers from Commission on Cancer (CoC) accredited cancer centers in the USA (https://www.facs.org/quality-programs/cancer/ncdb).

Patient Selection and Study Design

All adult patients (≥ 18 years old) who underwent colectomy for clinical T4b colon cancer in the period from 2010 to 2016 were included in this study. Patients with an unspecified surgical approach were excluded. Patients who underwent colectomy via (open vs minimally invasive surgical (MIS)) and (robotic vs laparoscopic) approaches were compared regarding the baseline characteristics as well as the short- and long-term outcomes. In addition, patients who underwent robotic-assisted colectomy were matched to those who underwent laparoscopic colectomy. Matching controlled for age, gender, race, Charlson Comorbidity Index (CCI), insurance type, income, hospital type (academic vs others), year of diagnosis, tumor location, tumor size, clinical N stage, clinical M stage, induction chemotherapy, and induction radiotherapy. Short- and long-term perioperative outcomes were compared between the matched groups.

In patients who underwent MIS colectomy, factors associated with conversion to an open approach were analyzed using uni- and multi-variable logistic regression analysis. Short- and long-term perioperative outcomes were compared between MIS patients who had or did not have conversion to an open approach.

Statistical Analysis

Data were reported as median, interquartile range (IQR), or frequency (percentage), for continuous and categorical data, respectively. Comparisons across the different study groups were performed using Mann-Whitney U test for continuous variables or Chi-square/Fisher’s exact tests for categorical variables. Factors associated with conversion to an open approach were analyzed using logistic regression analysis. Factors included in the univariable analysis included age, gender, race, Charlson comorbidity index (CCI), insurance type, income, year of surgery, tumor location, tumor size, clinical N stage, clinical M stage, neoadjuvant chemotherapy, neoadjuvant radiotherapy, hospital type, and surgical approach. Univariable factors with P < .20 were included in the multivariable model.

Propensity score (PS) matching analysis was performed between patients who underwent robotic-assisted colectomy to those who underwent laparoscopic colectomy. Nearest neighbor 1:1 PS matching was performed with no replacement using logistic regression algorithm with a Caliper of .2. Comparisons between the matched groups were performed using McNemar test (categorical data), and paired t-test (continuous data) to account for the paired nature of the matched groups. Kaplan-Meier method was used to estimate overall survival rate and differences between survival were compared using log-rank test. Patients with missing data in variables included in the MVA and propensity score matching analysis were excluded from those analyses. All statistical comparisons between the study groups were 2-sided and were considered statistically significant if P-value is <.05. Statistical analyses were performed using SPSS software (V.26) and PS-matching package (V.3.04 (IBM Corp, Armonk, New York).

Colectomy via Open or Minimally Invasive Approach

In this study, we assessed the differences in patients’ demographics, clinicopathological characteristics, perioperative outcomes and long-term overall survival between patients undergoing open or minimally invasive (laparoscopic or robotic) colectomy for T4b colon cancer. We found that patients who underwent minimally invasive colectomy had higher income, better insurance coverage (private/managed care insurance plans), and were more likely to have smaller tumor size, right-sided tumors, shorter hospital stay, and lower 90-day mortality, compared to those who underwent colectomy via an open approach.

Only a few retrospective, single-institution, studies have previously reported on the favorable perioperative outcomes associated with the use of a laparoscopic approach for the resection of T4b colon cancer. Nagasue et al ¹¹ reported their institution’s experience with 60 patients who underwent laparoscopic multi-visceral resection for colon cancer. ¹¹ In that study, the use of a laparoscopic approach was associated with longer operative time (271 vs 227 min), less blood loss, and shorter hospital stay (14 vs 18 days), compared with those who underwent open colectomy. However, there were no differences in R0 resection rate, number of harvested nodes, or perioperative morbidity between the two groups. Similarly, Takahashi et al ¹² reported on 48 patients who underwent multi-visceral resection for T4b colon cancer and found that the laparoscopic approach was superior to open approach regarding intraoperative blood loss, perioperative morbidity and length of hospital stay. ¹² The oncological outcomes were comparable between the two groups (R0 resection rate, overall and disease-free survival). In another study, Zhang et al ¹³ found that their 38 patients who underwent laparoscopic multi-visceral resection for T4b colon tumors had less blood loss and quicker return of bowel function compared to patients who underwent open colectomy. ¹³ Their results also suggested that the use of the laparoscopic approach might be associated with lower perioperative morbidity. The two groups had comparable operative time, overall and disease-free survival. Similar to the previously mentioned studies, Miyo et al ¹⁴ reported on 38 patients who had laparoscopic multi-visceral resection for T4b colon cancer and they found that the laparoscopic approach was associated with less blood loss, lower perioperative complications rate and shorter hospital stay compared to open colectomy, yet with comparable long-term survival rates. ¹⁴

We were able to identify only one study that reported on the use of a robotic colectomy approach for 28 patients with T4b rectal/sigmoid colon cancer. In that study, Crolla et al ¹⁵ reported favorable perioperative outcomes regarding operative time (median, 274 min), complete (R0) resection rate (86%), hospital stay (median, 6 days), and major postoperative complications rate of 14%. ¹⁵

Colectomy via Laparoscopic or Robotic Approach

Our study compared patients’ characteristics and perioperative outcomes of patients undergoing robotic or laparoscopic colectomy for T4b colon cancer. We found that compared to the laparoscopic approach, a robotic approach was more likely to be performed on patients with higher income, and was performed more commonly in community hospitals and for smaller tumors that located in the descending/sigmoid colon. More importantly, the use of a robotic approach was associated with lower rate of conversion to open approach, a lower rate of positive parenchymal resection margin, shorter length of hospital stays, lower 30-day readmission rate, and higher 5-year overall survival rate, compared to the laparoscopic approach in the unmatched cohort. Interestingly, even after matching the two groups (robotic and laparoscopic) to control for patients’ demographics and their clinical characteristics, the robotic approach remained associated with superior perioperative outcomes regarding lower rate of conversion to an open approach and shorter hospital stay. However, there was no difference in 5-year overall survival rate between the matched groups. We could not identify any studies in the literature that directly compared the robotic and laparoscopic approaches in this unique population of T4b tumors.

Conversion to Open Approach in Patients Who Underwent Minimally Invasive Colectomy

We found that the use of a robotic approach was associated with a significantly lower rate of conversion to an open approach. Besides the robotic approach, other factors that were associated with a lower rate of conversion included recent year of surgery and surgeries performed in an academic hospital. In addition, we found that patients in the conversion group had a higher rate of incomplete resection (R1/2), a longer hospital stay, and a higher rate of readmission compared to those who did not have a conversion. Interestingly, we found that patients in the conversion group had comparable long-term survival to those who did not have conversion. It is worth mentioning that for the patients undergoing laparoscopic colectomy for T4b colon cancer, the rate of conversion to an open approach in retrospective single institutional studies ranged between 5 and 30%^11-14 which is slightly lower than the one reported in this study (33%). Similarly, the rate of conversion associated with a robotic approach was found to be 11% by the study performed by Crolla et al ¹⁵ which is slightly lower than the 15% conversion rate reported in this study. ¹⁵ This might be due to the fact that those studies were performed in high volume, academic centers that have experienced surgeons with advanced minimally invasive surgical skills.

Study Limitations

This study is limited by its retrospective nature. In addition, the NCDB database lacks important information on diagnosis and treatment variables such as imaging modalities, adjacent involved organs, extent of resection performed, and causes of conversion to an open approach, amongst other.