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Robotic surgery resulted in better quality of resection for patients with middle and low rectal cancer compared with conventional laparoscopic surgery, a randomized trial in China showed.

In a modified intention-to-treat analysis involving 1,171 patients, 4% of those who received robotic surgery had a positive circumferential resection margin (CRM; ≤1 mm) versus 7.2% of those who underwent laparoscopic surgery (P=0.023), reported Jianmin Xu, PhD, of the Zhongshan Hospital Fudan University in Shanghai, and colleagues.

Furthermore, 16.2% of patients in the robotic group experienced at least one complication within 30 days of surgery versus 23.1% of laparoscopic patients (P=0.003), they noted in .

These two secondary short-term outcomes suggested better oncologic quality of resection for middle and low rectal cancer with robotic surgery, "with less surgical trauma and better postoperative recovery," Xu and team wrote.

The robotic group had better pathological outcomes, as evidenced by more macroscopic complete resections (95% vs 92%), as well as better gastrointestinal recovery with a shorter time to first flatus (38 vs 44 hours) and defecation (72 vs 84 hours), and shorter hospital stay (median 7 vs 8 days).

However, the statistically significant difference of lower CRM positivity with robotic surgery "was no longer apparent in subgroup analyses broken down by type of surgery (low anterior resection vs abdominoperineal resection), indicating that the difference in CRM positivity might be at least partly determined by difference in quality of the open transperineal dissection between groups," wrote Willem Bemelman, MD, PhD, and Roel Hompes, MD, PhD, both of the University of Amsterdam in the Netherlands, in an . "This questions if equally skilled surgeons did the two types of TME [total mesorectal excision]."

This trial was the first to assess the oncologic benefits of robotic surgery compared with laparoscopic surgery for rectal cancer. While researchers only reported secondary short-term outcomes, long-term outcomes involving their primary endpoint of 3-year pelvic/perineal locoregional recurrence are expected to be released in December 2023.

Laparoscopic surgery is commonly used in colon cancer, but its use in rectal cancer remains controversial, Xu's group noted. Prior trials showed laparoscopic surgery failed to achieve noninferiority of tumor radicality compared with open surgery. Other trials have shown that robotic surgery that uses three-dimensional vision with a stable camera platform and flexible arms is associated with more enhanced surgical quality versus laparoscopic surgery.

For this trial, Xu and colleagues enrolled 1,240 patients and randomized them 1:1 to receive robotic or laparoscopic surgery from July 2016 to December 2020 across 11 hospitals in China. Eligible patients were ages 18 to 80, with middle (>5 to 10 cm from the anal verge) or low (≤5 cm from the anal verge) rectal adenocarcinoma, without any distant metastasis.

The editorialists noted that the definition of middle and low rectal cancer was changed during the trial, with the inclusion criteria adjusted from less than 12 cm from the anal verge to less than 10 cm.

"Even the latter definition is no longer correct, since there is international consensus that the rectum starts below the sigmoidal take off," Bemelman and Hompes wrote. "Therefore, according to current definitions, several distal sigmoid tumors were also included in the study."

For the modified intention-to-treat analysis, 1,171 patients were included. Patient characteristics were similar between surgery groups, including pathological tumor staging. Mean age was 59-61, and 61% were men. About 43-44% received radiotherapy or chemoradiotherapy before surgery. Common comorbidities included hypertension (19%), diabetes (8%), and cardiovascular diseases (5-6%).

Six robotic surgery patients received laparoscopic surgery, while seven laparoscopic patients received robotic surgery.

Fewer patients in the robotic group experienced adverse outcomes during surgery versus laparoscopic patients:

• Abdominoperineal resections: 16.9% vs 22.7%
• Conversions to open surgery: 1.7% vs 3.9%
• Estimated blood loss: 40 vs 50 mL
• Intraoperative complications: 5.5% vs 8.7%

Within 30 days of surgery, two patients died -- one robotic patient from bowel necrosis and one laparoscopic patient from severe abdominal infection.

Total costs were higher with robotic surgery ($12,396 vs $8,171), but were lower in the postoperative period ($2,768 vs $3,060).

Xu and team acknowledged that no standard perioperative protocols were implemented across centers, which was a study limitation. Moreover, since this study was conducted in China, the findings may not be generalizable to other countries.

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