Radical Pelvic and Retroperitoneal Ovarian Cancer Surgery

Pelvis

In early stages, removal of the adnexa involved by tumor, a total abdominal hysterectomy with bilateral salpingo-oophorectomy, pelvic and paraaortic lymphadenectomy, and omentectomy are required as part of the surgical staging. Conservative procedures including unilateral salpingo-oophorectomy may be an alternative in young patients with early-stage disease and desire to preserve their fertility. In advanced stages, it is very common to find the internal genitalia (uterus and adnexa), the posterior cul-de-sac, the surface of the rectosigmoid colon, and most of the pelvic peritoneum, including the prevesical peritoneum and the lateral pelvic peritoneum, coated with tumor nodules of different dimensions (small implants, bulky nodules, or tumor plaques). Although it is not an infrequent occurrence for tumor to deeply infiltrate the rectosigmoid colon, it is very unlikely that the urinary tract itself is infiltrated by tumor.

The type of operation that should be performed is mainly dependent on the surgical findings, the tumor locations, and the surgeon’s expertise. The tumor tends to remain superficial, without a deep invasion of the adjacent organs. The retroperitoneum is almost always preserved from tumor infiltration. Removal of the tumor usually requires a retroperitoneal approach, which allows the identification of the vasculature and the isolation of the ureters laterally. At the same time, the peritoneum in the pelvis can be safely removed with the internal genitalia. If the tumor does not involve the wall of the rectosigmoid colon, the peritoneum of the pelvis and cul-de-sac can be stripped away. The lateral and anterior peritoneum is usually easy to dissect once the ureters have been lateralized, and the bladder is dissected off the uterus. If the tumor involves the wall of the rectosigmoid colon, a radical oophorectomy with en bloc resection of the rectosigmoid is preferred. Restoration of the bowel continuity is then performed and constitutes one of the most delicate parts of the surgical procedure. This chapter defines different approaches that can be used to remove all the tumor present in the pelvic area, according to the tumor distribution. This operation was first defined by Hudson as “radical oophorectomy” and subsequently has been redefined by several authors.

Surgical indications for this type of operation can be found in the context of either a cytoreductive effort (cytoreduction for primary or recurrent tumor) that brings the patient to no (or nearly no) macroscopic residual disease or a palliative goal of removing a tumor that is causing symptoms from a bowel obstruction. The patient must be evaluated preoperatively and judged able to withstand a complex procedure, and she must give consent for temporary bowel diversion if needed (intraoperatively or postoperatively because of complications).

Retroperitoneum

Accurate retroperitoneal staging is critical in patients with early ovarian cancer. The main value of the procedure lies in its ability to allow potential identification of nodal metastases; an appropriate adjuvant treatment method can be recommended according to the pathologic findings. In fact, a randomized trial comparing systematic pelvic and paraaortic lymphadenectomy versus nodal sampling showed that the ability to detect nodal metastases was higher in the lymphadenectomy arm (22% vs. 9%). Less adjuvant treatment was given in the lymphadenectomy arm, and a trend toward better progression-free survival (PFS) and overall survival (OS) was noted. A 2011 review examining the incidence of nodal metastases in 14 different studies showed that the mean incidence of pelvic or paraaortic nodal involvement in apparent stages I and II epithelial ovarian cancer was 14.2% (range, 6.1%–29.6%). In grade 1 tumors and with mucinous histology, the rate of nodal involvement was very low (almost negligible) ; for this specific reason, several authors do not recommend performance of systematic pelvic and paraaortic nodal dissection under these circumstances. Identifying those patients with disease grossly confined to the ovaries and pelvis but with retroperitoneal dissemination (stage IIIA1 according to the new International Federation of Gynecology and Obstetrics [FIGO] classification) may allow the most accurate adjuvant treatment planning. On the other hand, if patients truly have stage I disease, this may result in less adjuvant treatment if not indicated. If grossly involved nodes are found during the preoperative workup or during the operation, these should be removed as part of a debulking procedure.

In patients with advanced ovarian cancer, pelvic and/or paraaortic lymph nodes are a common site of metastasis, exceeding 50% of patients in most series.

A randomized trial comparing a systematic pelvic and paraaortic nodal dissection versus resection only of “bulky” nodes in patients with advanced ovarian cancer debulked to less than 1 cm has been completed. Although 5-year PFS was significantly higher in the lymphadenectomy arm (31.2% vs. 21.6%), OS did not statistically differ between the two arms (48.5% vs. 47%). In an analysis of data from three randomized trials in advanced ovarian cancer patients from the AGO (Arbeitsgemeinschaft Gynaekologische Onkologie) group, du Bois and colleagues showed a significant survival benefit in patients without residual disease but not in patients with a small amount of residual disease. They also found a significant impact of lymphadenectomy on survival in patients with low-volume disease and clinically involved bulky nodes. Although debulking of grossly involved nodes appears to be rational when a complete cytoreduction to no gross residual disease is performed in the abdominal cavity, the value of a complete lymphadenectomy when lymph nodes are not enlarged is not established. For this reason, an international prospective randomized clinical trial comparing systematic lymphadenectomy versus no lymphadenectomy in patients with advanced ovarian cancer debulked to no gross residual disease will probably be able to definitively address this issue. The trial has recently completed accrual.

The general approach for removing pelvic and paraaortic nodes is to access the retroperitoneum and define the anatomic structures and the surgical boundaries of the dissection. Removal of the pelvic nodes is commonly within the surgical armamentarium of most pelvic surgeons. Removal of the nodes from the paraaortic region usually requires greater expertise. Surgical steps include mobilization of the ascending colon, identification of the renal veins, and removal of the node-bearing tissue from the precaval and paracaval region, the intercavoaortic area, and the left paraaortic basins. Removal of bulky nodes can indeed be a challenge in both the pelvic and the paraaortic areas, and particular attention should be paid to the important structures (arteries and veins, nerves, ureters) to avoid injuries that can be difficult to manage. Anomalies of the vascular system (particularly in the aortocaval region) and in the urinary system are not uncommon, and while performing a retroperitoneal dissection, the surgeon should be aware of the different anomalies. In this respect, a careful evaluation of the preoperative imaging (computed tomography [CT] scan) is helpful in making an adequate surgical plan. Bulky nodes cephalic to the renal veins can also be a challenge in the debulking procedure. A common location of grossly involved nodes is at the level of the celiac axis. In this area, an injury of the superior mesenteric artery may in fact result in compromise of the blood supply to the small bowel.

This chapter describes a step-by-step procedure to remove the pelvic and paraaortic nodes.

Retroperitoneal Node Dissection

Three approaches to the surgical staging of ovarian carcinoma have been described: transperitoneal laparotomy, extraperitoneal laparotomy, and endoscopic approach. The endoscopic technique can actually be performed either transperitoneally or extraperitoneally as well as by means of laparoscopy or use of the da Vinci robotic surgical system. Endoscopic staging has the advantages of a more rapid recovery of the patient and a lower postoperative complication rate, thus avoiding significant delay in initiating adjuvant chemotherapy if necessary. In patients with advanced disease, however, laparotomy is recommended.

Pelvic Lymphadenectomy: Surgical Technique

The beginning of the procedure includes the definition of the margins of the operative field with the development of the avascular spaces of the pelvis and then the removal of the nodal tissue within those margins. Box. 13.1 gives a step-by-step description of pelvic lymph node dissection.

Step 1: Dissection of the Avascular Spaces of the Pelvis

The pelvic peritoneum is opened over the psoas muscle 1 cm lateral and parallel to the ovarian vessels. The posterior fossa or pararectal space is dissected laterally to the ureter and medially to the internal iliac artery ( Fig. 13.1 ). The uterine artery is the anterior limit, the lateral border of the rectum is the medial limit, and the internal iliac vessels are the lateral limits of the pararectal space ( Fig. 13.2 ). The round ligament is then divided, and the anterior peritoneum is incised laterally and parallel to the obliterated umbilical artery ( Fig. 13.3 ). The dissection progresses in depth, and the anterior fossa or paravesical space is developed. The lateral limit is the internal obturator muscle, the medial limit is the bladder, and the posterior limit is the uterine artery ( Fig. 13.4 ).

The distal external iliac vessels and lymph nodes are exposed by placing upward traction on the lateral part of the transected round ligament with a retractor to separate the fatty retrocrural nodal tissue from the peritoneum and undersurface of the inguinal ligament.

The external iliac artery and vein are separated from the psoas muscle. This step allows identification of the obturator fossa with the obturator nerve in the depth of this space.

The dissection starts proximally behind the bifurcation of the common iliac artery ( Fig. 13.5 ) and distally into the paravesical space, taking care not to injure the accessory obturator vein. The dissection over the psoas muscle is continued distally up to the deep circumflex iliac vessels.

The dissection progresses in depth, and the external iliac vessels are retracted medially and the psoas muscle is retracted laterally, allowing the identification of the obturator nerve, which emerges under the psoas muscle behind the bifurcation of the common iliac artery. The fat tissue containing the obturator nodes is stripped from the nerve for 3 to 4 cm into the obturator fossa. Special care should be taken because one or two small branches from the obturator artery to the pelvic wall are often encountered in the proximal obturator fossa; these are clipped. All vessels in the obturator fossa lie below the obturator nerve except the accessory obturator vein.