Evaluation of pilot experience with robotic-assisted proctectomy and coloanal anastomosis for rectal cancer

Background

Robotic-assisted proctectomy with coloanal anastomosis (RPCA) is an innovative technique of pelvic dissection for low rectal cancer. Our objective was to evaluate our pilot experience with this procedure compared with open proctectomy with coloanal anastomosis (OPCA).

Methods

We performed a retrospective 5-year review of all consecutive cases of RPCA and OPCA performed at our institute. We focused on tumour characteristics, quality of surgery, analgesic requirements, average length of hospital stay (LOS), complications and long-term outcomes.

Results

Three patients underwent RPCA and 25 had OPCA. The average duration of surgery was similar (288 min for RPCA v. 285 min for OPCA). Four patients in the OPCA group had positive or very close margins, and 2 had a mesorectal defect less than 5 mm. The average LOS was 6.66 and 9.29 days in the RPCA and OPCA groups, respectively, and the average duration of epidural or patient-controlled anesthesia was 2.67 and 5.16 days, respectively. We did not perform a statistical comparison because of the discordant size and sex distribution between the groups. There were no perioperative complications in the RPCA group, and all patients had negative margins and adequate lymph node retrievals with no long-term complications or recurrence recorded so far.

Conclusion

Our very early experience with RPCA is quite encouraging, suggesting that it is a safe alternative to OPCA with a similar duration and the added benefits of a minimally invasive procedure, including decreased LOS and reduced postoperative analgesic requirements.     

A new finite element approach for near real‐time simulation of light propagation in locally advanced head and neck tumors

Background and Objectives

Several clinical studies suggest that interstitial photodynamic therapy (I‐PDT) may benefit patients with locally advanced head and neck cancer (LAHNC). For I‐PDT, the therapeutic light is delivered through optical fibers inserted into the target tumor. The complex anatomy of the head and neck requires careful planning of fiber insertions. Often the fibers' location and tumor optical properties may vary from the original plan therefore pretreatment planning needs near real‐time updating to account for any changes. The purpose of this work was to develop a finite element analysis (FEA) approach for near real‐time simulation of light propagation in LAHNC.

Methods

Our previously developed FEA for modeling light propagation in skin tissue was modified to simulate light propagation from interstitial optical fibers. The modified model was validated by comparing the calculations with measurements in a phantom mimicking tumor optical properties. We investigated the impact of mesh element size and growth rate on the computation time, and defined optimal settings for the FEA. We demonstrated how the optimized FEA can be used for simulating light propagation in two cases of LAHNC amenable to I‐PDT, as proof‐of‐concept.

Results

The modified FEA was in agreement with the measurements (P = 0.0271). The optimal maximum mesh size and growth rate were 0.005–0.02 m and 2–2.5 m/m, respectively. Using these settings the computation time for simulating light propagation in LAHNC was reduced from 25.9 to 3.7 minutes in one case, and 10.1 to 4 minutes in another case. There were minor differences (1.62%, 1.13%) between the radiant exposures calculated with either mesh in both cases.

Conclusions

Our FEA approach can be used to model light propagation from diffused optical fibers in complex heterogeneous geometries representing LAHNC. There is a range of maximum element size (MES) and maximum element growth rate (MEGR) that can be used to minimize the computation time of the FEA to 4 minutes. Lasers Surg. Med. 47:60–67, 2015. © 2015 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.