Minimally invasive treatment strategies for rectal cancer

Stefan Erik van Oostendorp

    Research output: PhD ThesisPhD-Thesis - Research and graduation internal

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    Abstract

    The aim of this thesis was to explore the current state of transanal minimally invasive surgery (TAMIS) in the treatment of rectal cancer. Whilst TAMIS as technique for local excision has been accepted and positively evaluated since the introduction of transanal endoscopic microsurgery (TEM) by Gerhard Buess in 1988, advancement of the TAMIS approach further beyond the rectal wall to achieve a radical transanal total mesorectal excision (TaTME) was first published only in 2010. The perioperative safety of the TAMIS technique for local excision itself has been established over the past decades. Current focus lies in extending the role from benign adenomas and early rectal cancer (T1 limited to the most superficial part of the submucosa) towards local excision of more advanced rectal tumours potentially in combination with (neo)adjuvant chemoradiotherapy in the pursue of organ preservation. For TaTME perioperative safety has not been consistently reproduced at a comparative level as the standard laparoscopic approach and long-term outcomes are scarce and limited to cohort studies. Despite the absence of high-quality evidence supporting the oncologic safety of TAMIS local excision in combination with radiotherapy, various strategies have been already incorporated in institutional practices. Accurate preoperative staging of rectal cancer is of immense importance to offer precise tailored treatment such as organ preservation. Without accurate staging, it can lead to prevent potential under and overtreatment. Multidisciplinary teams rely on the mandatory preoperative MRI to triage patients with rectal cancer in need of neoadjuvant (chemo)radiotherapy. Whilst MRI is excellent to identify enlarged lymph nodes and to determine the growth of the tumour beyond the rectal wall, it underperforms in daily practice to distinguish T1 stage (limited to submucosa) from T2 stage. Therefore large excisional biopsy by local excision is suggested which may turn out therapeutic in a proportion of patients. These cases constitute of T1 low risk tumours who are thereby spared from a TME resection whilst the large biopsy can further direct additional treatment for other than T1 low risk tumours. The second part of this thesis concerns the Transanal Total Mesorectal Excision (TaTME) procedure, which involves a hybrid approach of a transabdominal laparoscopic phase and a transanal endoscopic single port phase. The simultaneous access to the pelvic cavity from above and below is claimed beneficial in the meticulous dissection along the holy plane (inner side of the mesorectal fascia) to achieve a complete specimen with clear margins. By completing the most difficult part of the operation which is the dissection deep in the narrowing pelvis from below, conversion to laparotomy is seldom required as the distal margin can be confirmed by direct endoluminal visualization. Additionally, this approach technically enables the construction of a very low stapled circular anastomosis due to the diathermic transection with a double purse string instead of cross-stapling through a linear stapled transection of the rectal tube. Patients who are deemed to benefit most from TaTME encounter the largest risk of a positive circumferential margin following TaTME. Therefore, it is recommended to commence with less challenging cases. TaTME should currently be regarded as a promising but complex solution for difficult rectal cancer cases. In the coming decade randomized controlled trials will have to show definitive oncologic safety and the indication for TaTME is likely further refined. Expanding the role of TAMIS local excision will likely increase beyond low risk early rectal cancer upon patient request. Whereas shared decision making is currently based on suboptimal evidence, several ongoing trials with prospective oncologic and patient reported outcomes will offer more reliable data enabling a better informed trade-off by individual patients between oncologic risk, morbidity, function and quality of life.
    Original languageEnglish
    QualificationDr.
    Awarding Institution
    • Vrije Universiteit Amsterdam
    Supervisors/Advisors
    • Bonjer, H.J., Supervisor, -
    • Tuynman, J.B., Co-supervisor, -
    Award date2 Jul 2021
    Place of PublicationAmsterdam
    Publisher
    Publication statusPublished - 2 Jul 2021

    Keywords

    • Rectal cancer, total mesorectal excision, transanal, surgery, organ preservation, TAMIS, TaTME

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