Phase-specific impact of patient anatomy on rectal cancer surgery: robotic assistance neutralizes dissection difficulty.

This study aimed to determine how patient anatomical characteristics influence the technical demands of rectal cancer surgery and to assess whether robotic assistance can moderate these effects. A retrospective analysis was conducted on 131 individuals who underwent minimally invasive low anterior resection at Kobe University Hospital (laparoscopic: n = 74; robotic-assisted: n = 57). The interval between the start of pneumoperitoneum and rectal transection—representing the dissection phase—was used as a proxy for technical difficulty. Associations between dissection time and body mass index (BMI), pelvic inlet measurements, tumor size, and sex were evaluated in each surgical modality using simple linear regression. In laparoscopic procedures, prolonged dissection time was significantly associated with higher BMI, a shorter obstetric conjugate diameter, and male sex. None of these relationships were observed in the robotic-assisted cohort. Estimated blood loss was lower in the robotic group, whereas postoperative outcomes, recurrence patterns, and three-year survival rates showed no meaningful differences between the two approaches. Robotic-assisted rectal surgery maintained stable performance across a range of challenging anatomical conditions—including obesity, narrow pelvic dimensions, and male pelvic anatomy—suggesting that robotic platforms may buffer technical difficulties during the dissection phase. Evaluating surgery through a phase-specific lens may offer a valuable framework for understanding procedural complexity in minimally invasive rectal cancer treatment.