Abstract
Port-site metastasis (PSM) is a rare complication of laparoscopic and robotic assisted oncologic surgery. The da Vinci Single-Port (SP) platform (Intuitive Surgical, Inc., Sunnyvale, CA) is increasingly utilized for urologic procedures including radical cystectomy, and given the need for fewer port sites, this should theoretically confer a lower risk for PSM. Here we describe a 74-year-old female with high-grade urothelial carcinoma (HGUC) of the bladder who underwent single-port robotic-assisted radical cystectomy (SP-RARC) and developed a metachronous metastatic nodule at her port site incision. To our knowledge, this represents the first reported case of PSM after SP-RARC.
Keywords: Bladder cancer, Radical cystectomy, Port site metastasis
1. Introduction
The standard of care for muscle invasive bladder cancer (MIBC) is neoadjuvant therapy followed by radical cystectomy with urinary diversion and bilateral pelvic lymph node dissection. Both open and robotic approaches to radical cystectomy are utilized, with similar oncologic outcomes observed.1 Multi-port robotic surgery is well-established, but the SP technique is gaining popularity as an even more minimally invasive robotic approach to radical cystectomy. Overall, patient outcomes between multi-port and SP robotic approaches to radical cystectomy are similar, but single-port surgery has been reported to facilitate faster return of bowel function.1 MIBC is an aggressive disease with 2-year and 5-year post-cystectomy recurrence occurring in 25% and 53% of patients, respectively.2,3 Of all recurrence sites, 1-11% can be considered atypical, with examples including peritoneal carcinomatosis, abdominal wall, stoma site, and port-site metastases.4 PSM is a rare finding, with only 20 cases reported in the literature. It is associated with aggressive disease, with the earliest PSM reported just 6 weeks after cystectomy.5 To the best of our knowledge, we present the first case of PSM in a patient who underwent SP-RARC.
2. Case presentation
The patient is a 74-year-old female with hypertension, diabetes mellitus, chronic renal disease, and no prior tobacco use with invasive high-grade urothelial carcinoma who completed three cycles of neoadjuvant dose-dense methotrexate, vinblastine, doxorubicin, and cisplatin (ddMVAC) before undergoing SP-RARC, hysterectomy, anterior vaginectomy, bilateral pelvic lymph node dissection, vaginal flap, and urinary diversion via extracorporeal ileal conduit. The procedure was performed using the da Vinci SP robotic platform with a separate 12 mm trocar site in the patient's left lower quadrant used as an assistant port. Intraoperatively, bladder and uterus specimen was removed through the vagina, and lymph nodes were removed with endoscopic retrieval bag. No urine spillage was noted. Final pathology revealed ypT4a pN0 with 3 cm high-grade urothelial carcinoma extending into the vaginal wall, with positive vaginal wall and soft tissue margins. All lymph nodes were negative for malignancy. The mass demonstrated little to no response to the neoadjuvant chemotherapy, with a similar appearance of the tumor noted on pre-chemotherapy imaging.
The patient's immediate postoperative course was uncomplicated. Due to the aggressive nature of her cancer, her case was discussed at our institution's Multidisciplinary Genitourinary Tumor Board with a final recommendation for 1 year of adjuvant nivolumab therapy. At her 5-month postoperative follow-up, the patient was noted to have a 2 cm nodule at the incision site where the assistant trocar had been. She states that it had been present for the last 3 months (Fig. 1, Fig. 2). She subsequently underwent wide local excision of the mass. Intra-operatively, it was noted that mass had a stalk-like projection extending from peritoneum, and a small fascial incision was made to completely excise the mass and stalk. The final pathology was consistent with high-grade urothelial carcinoma. Unfortunately, despite nivolumab adjuvant therapy, PET/CT at 7 months postoperatively from the SP-RARC showed metastatic disease to the ribs, sacrum, and acetabulum. She underwent palliative sacral radiation and has been started on enfortumab vedotin-ejfv and pembrolizumab.
Fig. 1.
Soft tissue nodule located at her prior incision site. (Photo reproduced with patient consent).
Fig. 2.
Axial image from non-contrast computed tomography (CT) obtained prior to patient's repeat surgery for mass excision. This imaging reveals the extension of the mass to the level of the peritoneum.
3. Discussion
The first report of PSM after multi-port robotic-assisted radical cystectomy (MP-RARC) was published in 2005, with more reports of PSM published as the use of MP-RARC grew.6 The primary risk factor for PSM is aggressive disease, which was present in this patient, with locally advanced disease, chemoresistance, and positive margins. While SP-RARC should theoretically have lower likelihood of PSM when compared to MP-RARC, given the need for fewer robotic trocars, this case demonstrates how aggressive disease can recur regardless of surgical approach.
The etiology of port site metastases is not completely understood, but there are several proposed theories. Principally, there is a correlation with incidence of PSM and tumor aggressiveness. Aggressive tumors are more likely to seed incision sites and cause PSM, and nearly all patients with PSM have additional locations of metastases.7,8
Intraoperative factors may also place patients at increased risk of PSM. Urinary spillage can carry malignant cells throughout the surgical site, and improper specimen extraction without the use of an endoscopic specimen retrieval bag can transfer malignant cells along the extraction site incisions.4 The “chimney effect,” whereby carbon dioxide gas leaks around the robotic trocars, is also a proposed mechanism by which aerosolized malignant particles could be brought into contact with the port site incisions.4 Finally, an additional theory is that the carbon dioxide gas may inhibit peritoneal tumor necrosis factor-alpha, leading to decreased antineoplastic reaction from the surrounding tissue.9
While most reports of PSM after robotic-assisted radical cystectomy do not include a description of which port site the metastasis arose from, the few studies that do mention location all indicate that the assistant port was the site of metastasis. In this case report, the metastasis also arose from the assistant port. The assistant port site may be more prone to metastases due to the opportunity for cancer cells to seed the incision during the more frequent instrument exchanges, and due to the increased manipulation of the trocar that theoretically amplifies the “chimney effect”.10 These risks will hopefully be minimized as SP surgical technique continues to advance with the introduction of tools that allow for reduced reliance on a surgical assistant like the Remotely Operated Suction Irrigation System (ROSI) and the SP SureForm 45 robotic stapler.
While there are some scattered reports of incisional metastases after open surgery, there is a marked paucity of literature on the subject. There is no reported incidence of incisional metastases after open radical cystectomy. Given the lack of literature, it is impossible to draw conclusions about the relative incidences of incisional metastases between robotic and open cystectomy.
4. Conclusion
Locally advanced disease, chemoresistance, and positive margins are all characteristics of aggressive disease, and these patients are at high risk for early and atypical recurrence. This case report documents the first published case of PSM in a SP-RARC, a technical, rather than mechanistic first, as all robotic approaches share the same possible mechanisms of tumor seeding. As SP-RARC grows in popularity and availability, further vigilance is necessary to understand the relative risks and benefits of this surgical approach over the standard MP-RARC. Current evidence suggests that strict adherence to oncologic surgical principles may reduce the risk of PSM. Additional prospective studies are needed to determine if SP-RARC has a lower risk of PSM when compared to MP-RARC. A more detailed understanding of the mechanism and incidence of PSM is likewise needed to further optimize surgical planning and oncologic outcomes in patients with aggressive disease.
CRediT authorship contribution statement
Anne Shirley Hoselton: Writing – original draft, Visualization, Conceptualization. Megan Sweeney: Writing – original draft, Investigation. Mark Mikhail: Writing – review & editing. John Lee Graves: Writing – review & editing. Amar Singh: Writing – review & editing.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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