Minimally invasive treatment approaches for early rectal cancer

The aim of this thesis is to investigate treatment strategies for early rectal cancer, with a focus on minimally invasive approaches, and to evaluate their clinical outcomes, risks, and implications for patient management. It also examines factors influencing treatment decisions, patient perspectives, surgical quality assessment, and variability in pathological evaluation. Chapter 2 provides an overview of treatment options for early rectal cancer, emphasizing the role of surgical local excision. Local treatment is increasingly used, often combined with (neo)adjuvant therapy, to avoid radical surgery while achieving favorable outcomes. Although local excision fits within multiple strategies, its oncological reliability requires multidisciplinary assessment to support informed shared decision-making. Chapter 3 presents a population-based study comparing primary total mesorectal excision (TME; one-stage approach) with local excision followed by completion TME (two-stage approach). Data from 1062 patients with cT1–2N0 rectal cancer treated between 2012 and 2020 were analyzed. Use of the two-stage approach increased from 22.3% in 2015 to 43.9% in 2020. After propensity score matching, the end-ostomy rate was significantly higher in the two-stage group (29.6%) than in the one-stage group (16.8%), while pathological outcomes and complications were similar. Chapter 4 extends this comparison by examining transanal approaches and long-term outcomes in six Dutch high-volume TaTME centers. Among 150 patients with cT1–2N0 rectal cancer, those undergoing primary transanal TME (pTaTME) had a higher end-ostomy rate (42% vs. 21%) but a trend toward fewer anastomotic leaks (18% vs. 33%). No significant differences were found in pathological or oncological outcomes. Chapter 5 presents a systematic review assessing the incidence and distance of distal mesorectal spread (DMS) to define the required distal margin in partial mesorectal excision (PME). Across 22 studies involving 1921 patients, DMS occurred in 10.8% of cases, with substantially lower incidence after neoadjuvant chemoradiotherapy (1.2% vs. 12.8%). Mean and median spread distances were about 20 mm, and spread exceeding 50 mm was rare. These findings suggest that a routine 5 cm distal margin may lead to overtreatment and support further prospective research into smaller margins guided by advanced imaging and pathology. Chapter 6 explores perspectives of patients and healthcare providers through 20 semi-structured interviews. Patients emphasized the risk of a stoma, bowel function, and postoperative complications, while healthcare providers more often cited recurrence risk, stoma risk, and bowel function. Patients appeared more willing to prioritize quality of life over oncological outcomes than clinicians assumed, underscoring the importance of aligning decisions with patient values. Chapter 7 examines video-based surgical quality assessment (SQA) tools in laparoscopic procedures. Forty-one unique tools were identified, including global assessment scales, error-based tools, procedure-specific instruments, and AI-based systems. Twelve studies evaluated associations between SQA results and clinical outcomes, with eleven showing positive correlations between higher surgical quality and improved postoperative results. These findings support the use of validated SQA tools for surgical education, research, and quality improvement. Chapter 8, a substudy of the TESAR trial, investigates interobserver variability in histopathological evaluation. Among the first 126 patients, discrepancies between original and central pathology review occurred in 57.9%, with 28.6% involving key risk factors. Lymphovascular invasion showed the highest variability, leading to treatment modifications in 11% of patients. This underscores the need for expert pathology review. Chapter 9 describes the first documented case of anal metastasis caused by iatrogenic tumor cell seeding during minimally invasive rectal surgery. A 57-year-old man developed an anal metastasis 23 months after TAMIS using a Lone Star retractor. Pathology confirmed its origin from the primary carcinoma. This case emphasizes the importance of careful tissue handling and rectal washout to minimize recurrence risk. These findings collectively inform clinical practice today.