**5.3 Extended indications in rectal tumors: TEM after neoadjuvant chemoradiotherapy**

Neoadjuvant chemoradiotherapy (n-CRT) is recommended by the European Society of Medical Oncology (ESMO) in cases of: advanced disease (T3c/T3d and over), MRI-predicted circumferential radial margin (CRM) (<1 mm), and lymph node involvement at MRI [25]. These characteristics of the tumor define the risk of local recurrence and metastatic disease, so the goal of n-CRT is to downsize or downstage the tumor and to avoid disease progression. Short-course neoadjuvant radiation therapy involves 25 Gy administered in doses of 5 Gy daily in 1 week, followed by surgery 1 week after completing neoadjuvant therapy; in 1997, the Swedish Rectal Cancer Study Group found a significant reduction in local recurrence rates between irradiated and control group [26]. Neoadjuvant longcourse chemoradiation therapy described by Marks et al. [27] includes an overall administration of 50, 40 Gy in 28 fractions over 5 weeks, with concurrent continuous intravenous infusion of 5-FU. The radiation is administered in the areas of the anus, rectum, mesorectum, regional and iliac lymph nodes. Surgery is performed between 45 and 55 days after completion of chemoradiotherapy.

The standard treatment for T2–T3 rectal cancer after neoadjuvant chemoradiotherapy (n-CRT) is low anterior resection (open or laparoscopic approach) with total mesorectal excision (TME) [28, 29]. However, some studies report that combination of n-CRT with TEM is feasible in T2 and T3 rectal cancers [30, 31]. In a prospective randomized controlled trial, at a 5-year follow-up in selected post n-CRT patients with T2 rectal cancers, the local recurrence rates, the disease-free survival, and distant metastases rates showed no statistical difference in patients receiving TEM or TME [32]. Furthermore, the combination of n-CRT with TEM showed also advantages in preserving patients' anal function and in lower disruption of patients' quality of life [33–35].


*Sm: submucosal layer invasion [21].*

Nevertheless, despite extensive mesorectal fat dissection during endoluminal loco-regional resection (ELRR) by TEM, in these patients the N parameter may remain incompletely defined, which may be a cause of concern. In the literature, an original modified sentinel lymph node procedure called nucleotide-guided mesorectal excision (NGME) [36] is described, which can improve the lymph node harvest during endoluminal resection by TEM/TAMIS and consequently obtain a better staging accuracy. During NGME, injection of 99 m-technetium-marked nanocolloid is performed in the peritumoral submucosa before starting the procedure. After specimen removal, the residual cavity is probed with a gamma camera in order to survey any residual radioactive area. In case of positivity, these areas are excised by TEM/TAMIS.

TEM may also be used when the focus is on palliation, if a curative treatment is impossible, in > T3 tumors in patients with unresectable metastases.

### **5.4 Other indications**

Other types of rectal tumors can also be treated with TEM or TAMIS approaches, such as neuroendocrine tumors, leiomyoma, gastrointestinal stromal tumors [25, 23].

TEM can also be used for treatment of iatrogenic fistulae after general surgery and gynecological or urological procedures, such as after prostatectomy or for management of recto-vaginal and recto-urinary fistulae [37–39]. Benign rectal strictures can also be treated by TEM [40, 41].
