Transanal minimally invasive surgery (TAMIS) versus transanal endoscopic microsurgery (TEM): is one better than the other?

We read with interest the recent publication by Rimonda et al. [1] comparing transanal minimally invasive surgery (TAMIS) using a SILS Port (Covidien, Mansfield, MA) with the more traditional transanal platform, transanal endoscopic microsurgery (TEM), for local excision of rectal neoplasms. We congratulate them for their effort to provide the first comparative study of the two platforms. However, an unexplained disparity exists between the findings of this small ex vivo study (n = 10) and the data obtained from multiple clinical series on TAMIS referenced by the authors (combined n = 109). The first report of using a multichannel port transanally was published by our group in this journal on 21 February 2010, and this approach was named TAMIS [2]. Subsequently, other investigators reported their experience with various multichannel ports [3–6]. In each of these publications, however, the conclusion was the same: this new approach for transanal surgery is feasible and safe, with encouraging clinical results. In these studies, no significant difficulty was reported. Instead, investigators typically pointed to the elegant simplicity of TAMIS as one of its principal advantages, which contradicts the findings in this comparative trial. These other clinical data thereby validate TAMIS, and this, in fact, has led to United States Food and Drug Administration (FDA) approval of two multichannel ports for use with TAMIS (SILS Port by Covidien, and GelPOINT Path Transanal Access Platform by Applied Medical, Inc., Rancho Santa Margarita, CA). Using their ex vivo comparative model, the authors concluded that TEM has a significant advantage, particularly with closure of the surgical defect, and emphasized that this was more technically challenging when performed with the TAMIS platform. They cite this difficulty as a key reason why TEM was preferred over TAMIS by the surgeons (neither of whom was experienced with either platform). But the comparison represents a limited construct and does not account for surgeon skill level, training, or experience. Nor does it account for the various types of TAMIS platforms available or the accessory devices commonly used by TAMIS surgeons, such as automated suturing and knot-forming devices. These devices aid significantly with the more technically demanding part of TAMIS, namely, closure of the surgical defect after local excision has been completed. Such automated devices, readily available from industry, are tools commonly used by seasoned TAMIS surgeons. These devices allow for rapid and accurate closure of rectal wall defects and have resulted in excellent outcomes. The TAMIS platform allows surgeons to translate familiar laparoscopic skills to transanal surgery, which is expected to result in rapid acquisition of the skill necessary for competency. Despite this advantage, the authors found the TAMIS approach to be difficult. Perhaps difficulty, however, should not be the litmus test of a new technique. Traditionally, safety and efficacy are considered more relevant parameters. A more durable method for validating TAMIS is to compare clinical outcomes obtained using this platform with those obtained using TEM. In the largest series to date on TAMIS for local excision of rectal neoplasia (n = 50), the rate of locoregional recurrence and tumor fragmentation was found to be comparable with those reported for TEM, and no appreciable difference in morbidity was S. B. Atallah (&) M. R. Albert Center for Colon and Rectal Surgery, Florida Hospital, Orlando, FL, USA e-mail: atallah@post.harvard.edu