Adrenocortical Carcinoma: The Posterior Minimally Invasive Approach

Abstract

Adrenocortical carcinoma (ACC) is an aggressive cancer, and comprehensive preoperative assessment, including imaging and staging, is essential to determine the feasibility of a minimally invasive approach. Posterior retroperitoneoscopic adrenalectomy (PRA) has emerged as a valuable surgical approach for managing different adrenal pathologies, as it maximizes the current advantages of the minimally invasive technique such as a shorter operative time, less pain, and a shorter hospital stay. However, selection of the best surgical treatment for ACC should be individualized based on factors like tumor size and stage of the disease, and it often requires a multidisciplinary approach involving surgeons, oncologists, and endocrinologists to optimize the outcome and follow-up care. While the surgical management of ACC necessitates en bloc oncological removal of the tumor with the retroperitoneal fatty tissue, PRA can be proposed for selected patients as it offers a direct approach to the retroperitoneum. In this chapter we describe the potential indications and the surgical technique for PRA in the treatment of ACC.

11.1 Introduction

Application of minimally invasive surgery in the surgical management of adrenocortical carcinoma (ACC) sparks ongoing debate, despite some evidence indicating its potential to achieve comparable outcomes to open surgery, particularly among patients falling within stages I and II according to the European Network for the Study of Adrenal Tumors (ENSAT) [1, 2]. Nevertheless, it is important to acknowledge that the quality of evidence derived from these observational studies is regarded as very limited [3]. The specific role of the posterior retroperitoneoscopic adrenalectomy (PRA) remains unclear, given the scarcity of literature detailing its outcomes in the context of ACC treatment. In this chapter we describe the potential indications and the surgical technique for PRA in the treatment of ACC.

11.2 Surgical Technique

The description of PRA, which we pioneered, was first documented in 1995 [4], with subsequent significant refinements outlined in 2006 [5]. The patient is positioned in a prone, half-jack-knife position, with the lower legs forming a 90° angle with the thighs. To provide the necessary access below the ribcage, a rectangular cushion is inserted between the operating table and the patient’s abdomen, allowing the abdominal wall to dangle anteriorly. Alternatively, a bolster can be placed beneath the chest and pelvis. A skin incision of about 2 cm in length is made at the level of the 12th rib, and access to the retroperitoneal space is achieved through a combination of blunt and sharp dissection using scissors. The retroperitoneum is further opened, and the space expanded by introducing a finger. Subsequently, a 5-mm port is carefully inserted just beneath the tip of the 11th rib under digital guidance. A blunt trocar equipped with an inflatable balloon and an adjustable sleeve (Medtronic, Minneapolis, USA) is introduced into the initial incision and securely positioned. Carbon dioxide insufflation is initiated, beginning with a pressure of 20 mmHg, which may be adjusted up to 30 mmHg depending on the patient’s characteristics, such as their degree of obesity and the extent of retroperitoneal fatty tissue, as well as the size of the tumor. The creation of a working space involves the dissection of Gerota’s fascia and the gentle displacement of retroperitoneal fatty tissue in a ventral and caudal direction. This maneuver can already allow for the visualization of both the kidney and the adrenal gland. A third trocar (5- or 10-mm) is inserted medially, positioned below the 12th rib, all while maintaining visual control and taking care to avoid any damage to the subcostal nerve that runs parallel to the rib. Therefore, the tip of the third port should be blunt. The dissection commences on the lateral aspect of the upper pole of the kidney, with the objective of mobilizing the kidney and releasing it from any adhesions to the retroperitoneal fatty tissue. Subsequently, the kidney is retracted and turned in a caudal and medial direction to expose the lower pole of the adrenal gland. Depending on the distinct anatomical position of the left and right adrenal glands, the mobilization of the kidney should be more extensive on the left side. Extremely helpful are modern bipolar or ultrasonic instruments. The dissection proceeds from lateral to medial taking down the fatty tissue between kidney and adrenal gland. By this horizontal dissection on the anterior Gerota’s fascia feeding branches from the renal artery are cut. On the right side the inferior vena cava (IVC) is identified medially, usually close to the entrance of the right renal vein, which is directly visualized only in cases of very large or caudally located adrenal tumors. Afterward the vertical retrocaval dissection is meticulously carried out until reaching the adrenal vein. It is common to encounter small arteries running horizontally behind the IVC, that are all typically dissected and divided. On the left side, the adrenal vein is isolated medially to the lower pole of the adrenal gland. In cases where adrenalectomy is performed due to suspected ACC, a modification of the technique may be considered to extend the resection in order to include regional lymph nodes. On the right side, the renal artery and vein can be identified, and the dissection line closely follows the renal vessels until reaching the inter-aortocaval region, enabling the removal of fatty tissue that encompasses the para-adrenal and inter-aortocaval lymph nodes. This meticulous dissection exposes the entire posterior wall of the vena cava, facilitating the continuation of lymphadenectomy until the right crux is reached. Approximately at the upper third of the adrenal gland, the short adrenal vein is then isolated and divided. On the left side, the renal artery is identified and dissected free until its origin at the aorta is reached. The removal of the left paraaortic fatty tissue, along with the lymph nodes, is carried out, allowing for visualization of the aorta up to the level of the left crux. During this step, the left adrenal vein, which converges into the renal vein, and the inferior diaphragmatic vein are naturally identified. The division of the adrenal vein is routinely performed using energy devices. Subsequently, the cranial dissection marks the next stage of the procedure, and it is followed by dissection of the posterior peritoneal layer on the right side and the lamina between the pancreas and the adrenal gland on the left side. These layers may be excised en bloc with the tumor, revealing the right posterior liver segments on the right side and the pancreas along with the splenic vessels on the left side. The opening of the peritoneal layer does not significantly impede the operating space, ensuring the safe completion of the procedure. The specimen is carefully placed within a retrieval bag and pulled through the middle incision. If necessary, in-bag fragmentation of the specimen can be performed to facilitate its extraction. Suction drains are typically not utilized.

11.3 Discussion

The use of minimally invasive techniques in the surgical treatment of ACC remains a topic of ongoing discussion. Current guidelines advocate open surgery as the standard approach for confirmed or highly suspected ACC. However, for tumors measuring less than 6 cm without any sign of local invasion, minimally invasive adrenalectomy, adhering to oncological principles, can be considered [6]. While there is no conclusive evidence in the literature, experts generally believe that a minimum annual caseload of six adrenalectomies per year is necessary to maintain sufficient proficiency in adrenal surgery. However, for those engaged in ACC surgery, performing over 20 adrenalectomies per year is highly desirable [6]. An analysis of data from the US National Cancer Database from 2010 to 2014 revealed that among 196 patients who underwent attempted laparoscopic adrenalectomy for ACC, 38 individuals (19.4%) required conversion to an open surgical procedure [7]. Notably, risk factors for conversion included larger tumor size (9 cm) and the need for a right-sided adrenalectomy. The conversion rate was lower in patients who underwent robotic procedures (10.9%) compared to those who had laparoscopic procedures (22.0%), with a p-value of 0.095. This suggests that the utilization of articulated arms in robotic surgery may aid in dissection, particularly in cases involving larger tumors, potentially reducing the need for extensive manipulation. Furthermore, the same study demonstrated that conversion significantly impacted overall survival at 2 years and was associated with a higher incidence of R1 resections. No studies in the literature have reported the outcomes of PRA for ACC in a cohort of patients. Previous studies from our group included single cases treated by PRA and do not allow any conclusion about the oncological appropriateness of the procedure. In a paper from 2005, the experience with 33 PRA for primary adrenal tumors >6 cm selected from a prospective series of 429 minimally invasive adrenal operations was published [8]. There were no perioperative deaths. Patients with large tumors had an increased conversion rate (p = 0.039), longer operating time (p < 0.001) and greater intraoperative blood loss (p = 0.007) than those with smaller lesions, but a similar overall morbidity rate (p = 0.207). Six malignant tumors were identified in this series (diameter 4–10 cm; four pheochromocytomas and two ACCs). Local recurrence developed in two patients and distant metastasis occurred in all six patients with malignant lesions. Given that minimally invasive adrenalectomy has showcased numerous advantages over open surgery in the treatment of the majority of adrenal masses, including reduced blood loss, shorter recovery periods, and diminished postoperative pain [9], it seems reasonable to consider this approach for localized (stage I–II) ACC. As per several studies [10, 11], which found no significant differences in oncological outcomes, it can be concluded that laparoscopic adrenalectomy may be considered a viable choice for treating localized ACC, provided that appropriate patient selection criteria are met and surgical adherence to oncological principles is maintained. However, it is essential to evaluate these findings with caution due to the retrospective nature of the studies and the relatively small number of patients included. The maximum tumor diameter that can be safely approached using minimally invasive techniques remains a subject of uncertainty. For laparoscopic adrenalectomy, a proposed limit of 10 cm has been suggested [10]. This size limit appears to be acceptable also for PRA. However, it is challenging to provide a definitive recommendation due to the absence of published data in the literature. Therefore, any opinion on this matter can only be offered based on the experience gathered over the years. Opting for a minimally invasive approach when dealing with a tumor larger than 6 cm should be done cautiously, taking into account several individual factors. These factors include the patient’s dimensions, the quantity of retroperitoneal fatty tissue, the potential presence of enlarged lymph nodes, and the surgeon’s personal experience and proficiency with the technique (Fig. 11.1). This is especially critical when conducting minimally invasive lymphadenectomy or multivisceral resection. PRA allows for the feasible execution of left para-aortic and right paracaval lymphadenectomy, extending to the hilum of the kidney and the infrarenal region. This technique offers a direct path to the retroperitoneal area, bypassing the need to mobilize intra-abdominal organs and reducing the risk of potential injuries of intra-abdominal organs (Fig. 11.2). However, it is crucial to note that in the event of suspected involvement of interaortocaval lymph nodes in the case of left-sided tumors or contralateral lymph nodes (for both sides), a bilateral retroperitoneoscopic approach should be taken into account allowing a systematic lymphadenectomy. Patients whose preoperative imaging strongly suggests infiltration of adjacent organs, necessitating the consideration of multiorgan or compartment resection, are typically not suitable candidates for minimally invasive approaches as well. Nevertheless, infiltration of adjacent organs, primarily the kidney, is often only suspected at preoperative imaging and an endoscopic approach is still possible in many cases. Early conversion to open surgery should be considered in cases of intraoperative confirmation of infiltration. In ACCs with small tumor thrombus in the IVC, we demonstrated a complete venous vascular control by PRA (Fig. 11.3). By clamping the IVC segment between conjunction of the renal veins and high retrohepatic, an en bloc resection of ACC and thrombus can be performed by excision of the adrenal vein at entering the IVC. The venous defect has to be closed with a running suture [12]. Of course, this approach is reserved for highly selected patients and requires advanced skills in endoscopic surgery.

Fig. 11.1

Computed tomography scan of right-sided adrenocortical carcinoma, 35 W. Posterior retroperitoneoscopic approach contraindicated because safe circumferential dissection impossible due to tumor size (15 cm ∅)

Fig. 11.2

Computed tomography scan of left-sided adrenocortical carcinoma, 36 M. En bloc resection including regional lymphadenectomy by posterior retroperitoneoscopic approach (red dotted line)

Fig. 11.3

Magnetic resonance imaging of right-sided adrenocortical carcinoma with tumor thrombus in inferior vena cava (arrow), 20 W. Posterior retroperitoneoscopic adrenalectomy including removal of tumor thrombus by adrenal vein excision

11.4 Conclusions

PRA proves to be both feasible and safe for patients diagnosed with adrenal pathologies and demonstrated to have a similar complication rate in patients with larger tumors. It can be considered a viable alternative to open or laparoscopic adrenalectomy, especially for patients with tumors measuring 10 cm or less. This technique also allows for lymphadenectomy and the resection of more advanced tumors, but only in carefully selected patients. Nevertheless, long-term oncological results are still missing.