TME is the gold standard surgical treatment of rectal cancer. Specimen quality, integrity of mesorectal fascia and lymph nodes harvest are expression of radicality and good surgery. The LOTARTME study is designed to assess which of the open, laparoscopic, robotic and endoscopic transanal approach is superior. Primary outcome is the evaluation of completeness of mesorectal fascia according to Quirke classification. Secondary outcomes are lymph nodes harvest, local recurrences, overall survivals, cancer related survivals. Inclusion criteria: any patient of any age and sex undergoing to intent-to-treat surgery operated by experienced surgeon. Exclusion criteria: patients with rectal cancer undergoing palliative surgery or multivisceral resection; all patients operated by less experienced surgeons. Study period January 1, 2017 - June 30 2021 and patients enrollment: January 1, 2017 - December 31, 2020. Data collection and analysis: data are collected in a prospective database and statical analysis is carried out using AnalystSoft StatPlus for Windows Software.

Developed in 1992 by Heald Total Mesorectal Excision improved the long-term results of rectal cancer treatment with overall survivals increasing up to 80% and local recurrences decreasing down to 4%. Notwithstanding the introduction of laparoscopy and robotic technology and their application in the field of rectal cancer surgery in the last decades, no further improvement of rectal cancer survivals have been reported. Actually, completeness of mesorectal fat and fascia excision seems not to be improved with these new approaches, compared to standard open surgery. It has been proved that local recurrences are strictly related to the quality of TME and are significantly higher when mesorectal fascia is incomplete according to Quirke classification. In 2012 A. Lacy first reported the transanal approach to TME, developed to overcome the high challenges represented by low rectal dissection when difficult anatomy is present (i.e. obese pts, narrow pelvis, bulging tumors) that may impair the quality of surgical specimen and, therefore, increase the incidence of local recurrences and, indirectly, overall cancer related survivals. There is an ongoing clinical trial (COLOR III) that has been designed to assess whether long term results after TaTME are similar, better or worse than those of open or laparoscopic TME. Until then scientists and researchers may evaluate the effectiveness of TaTME compared to other surgical approaches (open, laparoscopic, robotic) assessing the quality of surgical specimens (i.e. completeness of mesorectal excision and integrity of mesorectal fascia according to Quirke classification). Investigators have designed a prospective observational cohort study assessing the quality of specimen and mesorectal fascia in all patients undergoing TME through an open, laparoscopic, robotic and transanal (TaTME) approach between January 2017 and December 2020. All patients have been followed-up with a required minimum follow-up of 6 months. Therefore, the study was terminated on June 2021. Inclusion criteria were: any patient of any age and sex undergoing intent-to-treat surgery operated by experienced surgeon (with ≥ 100 TME performed). Exclusion criteria: patients with rectal cancer undergoing palliative surgery or multivisceral resection, all patients operated by less experienced surgeons (< 100 TME performed).

Objective of the study:

Assessing the quality of the specimen after TME carried out through laparoscopic, open, robotic and endoscopic transanal approach; evaluating whether TaTME might be superior the other approaches in term of radicality of surgery and local recurrencies.

Primary outcome:

Quirke classification of mesorectal fat and fascia completeness. Three grade classification: complete, nearly complete, incomplete.

Secondary outcomes Lymph node harvest Local recurrences Overall survivals Cancer specific survivals Pathology assessment

A fresh specimen or in vacuum packing is sent for macroscopic assessment to the pathologist. The specimen is dealt as follows:

1) assessment of mesorectum quality; 2) ink painting of specimen non-peritonealized bare areas 3) the specimen is opened along the anterior aspect from the top and the bottom, leaving the bowel intact at a level just above and just below the tumour; 4) placement of formalin-soaked gauze wicks into the unopened ends of the bowel; 5) the specimen is fixed in 10% buffered formalin for at least 48 hours.

The fixed specimen is dealt as follows:

1) 3-5 mm intervals slices through the unopened rectum; 2) slices inspection to note: extent of tumour and the closest distance of tumour to the Circumferential Resection Margin (CRM); positive nodes and the distance of any positive node to the CRM; anterior, posterior or lateral closest distance of tumour to CRM; 3) lymph nodes detection within the fat away from the tumour

Block selection according to the followings:

1) tumor blocks showing closest CRM; 2) tumor blocks showing luminal aspect, 3) all lymph nodes; 4) any polyps; 5) proximal and distal resection margins (distal margin includes both mucosa and mesorectum).

The pathologist examined the specimen in a blinded fashion (unaware of the name of the operating surgeon and the technique performed).

Data are collected in a prospective database. Statistical analysis is carried out with AnalystSoft StatPlus for Windows Software. Chi-square test and chi-square test with Yates correction are used considering p-value significative at p<.05.

Inclusion Criteria:

• intent to treat procedures
• procedures performed by experienced surgeons (minimum of 100 TME)

Exclusion Criteria:

• palliation surgery
• multivisceral resections
• procedures performed by inexperienced surgeons (less of 100 TME)

Stage 1 and 2 rectal cancer patients (preoperative assessment) undergoing surgery without neoadjuvant chemoradiation therapy.

Stage 3 and 4 rectal cancer patients undergoing surgery after long-term or short-term chemoradiation therapy.