Modular Pelvic Exenteration for Advanced Rectal Cancer in Frozen Pelvis

Background

Colorectal cancer is the most common malignant neoplasm of the gastrointestinal tract [1]. With the development of chemo-therapy, anti-angiogenic medicine, immune-checkpoint inhibitors, and radiotherapy, rectal cancer survival has improved; however, surgery remains the most important approach to treat rectal cancer. The multiple pelvic organs and complicated anatomical structures make surgeries for locally advanced rectal cancers challenging. For locally advanced rectal cancer with adjacent organ involvement, surgical resection can be the only treatment option if the tumor does not respond well to chemotherapy, radiotherapy, and immune checkpoint inhibitors, or the patient cannot tolerate the adverse effect of these therapies. Some studies indicated that pelvic exenteration offers selected patients with locally advanced rectal cancer the chance of long-term survival [2–4]. The ultimate stage of locally advanced rectal cancer is called a “frozen pelvis” status, which means the tumor not only involves pelvic organs or tissues but is also occupied and fixed in the whole pelvic cavity, making the surgery extremely challenging. There are few reports in the literature about the surgery for rectal cancer in frozen pelvis. A successful resection for locally advanced rectal cancer in frozen pelvis should aim to achieve en bloc re-section with a clear resection margin, and the resection extent should include the possible metastatic pelvic sites. To achieve this, we designed a modular pelvic exenteration strategy for locally advanced rectal cancer in frozen pelvis and aimed to achieve an en bloc resection and a clear resection margin. This strategy was implemented in 1 case and achieved a favorable short-term result.

Case Report

A 51-year-old man had a diagnosis of rectal cancer. The patient was without any previous health hazards, such as tobacco use or alcohol and drug abuse. When he received the diagnosis, he was generally in good condition, with a hemoglobin level of 126 g/L, albumin of 37.4 g/L, carcinoembryonic antigen (CEA) of 3.59 ng/mL, cancer antigen 19-9 (CA19-9) of 13.96 U/mL, and body mass index (BMI) of 27.76 (175 cm, 85 kg). The preoperative tumor-node-metastasis (TNM) classification by imaging was labelled T3N+M0. The preoperative endoscopic biology revealed well-differentiated adenocarcinoma. The tumor was approximately 1 cm above the anal margin. The doctors provided the patient with proper informed counsel, informing him that if he did not accept the operation, future symptoms, such as bowel obstruction, bleeding, and intestinal perforation due to tumor progression and invasion could appear. However, the patient refused the surgery because the radical resection entailed sphincter sacrifice. One year later, the patient experienced syncope and visited a local hospital emergency department, where he received a diagnosis of anemia. His hemoglobin level was 5.6 g/L, which improved to 9.0 g/L after blood transfusion. Computed tomography (CT) revealed a progression of the tumor. The patient refused surgery again and was not suitable for immune-checkpoint inhibitors, as the tumor had microsatellite stability; therefore, XELOX regimen chemotherapy was planned. However, chemotherapy was discontinued after 1 session owing to severe anaphylactic reactions, including bronchospasm, dyspnea, and hypo-tension. The patient refused any other treatment. Six months later, the patient developed dysuria and gross hematuria. In another cancer center, CT revealed tumor invasion of the urinary bladder. Radiotherapy (50 Gy/25 times) was administered since the patient refused surgery and could not tolerate chemotherapy. The radiotherapy regime was performed for 5 sessions (every session 2 Gy/day, days 1–5). The dysuria was gradually relieved after radiotherapy. However, the radiotherapy response was not evaluated by image examination. Two months after finishing the last session of radiotherapy, the patient developed turbid urine, pneumaturia, hematochezia, and aggravated anal pain. The hemoglobin level dropped down to 5.4 g/L. After an emergent blood transfusion in a community hospital, he was transferred to our hospital for further evaluation and treatment. At admission, the patient had a poor nutritional status, with a hemoglobin level of 54 g/L, albumin of 27.1 g/L, CEA of 4.80 ng/mL, CA19-9 of 11.46 U/mL, and BMI of 17.96 (175 cm, 55 kg). CT and magnetic resonance imaging (MRI) revealed diffuse rectal wall thickening, rectovesical fistula, involvement of the seminal vesicles, prostate, and mesorectal fascia, multiple lesions around the anorectum and prostate, consistent with abscesses, thickened and rigid bladder wall, consistent with cystitis or appearances after radio-therapy or tumor infiltration, bilateral distal ureteral involvement, bilateral hydroureterosis, and hydronephrosis (Figure 1). Cystoscopy revealed a turbid and rigid bladder wall, and the trigone could not be distinguished. At this time, the patient’s rectal cancer was labelled T4bN+M0; the tumor was fixed in the pelvic cavity, revealing a frozen pelvis status, without distant metastasis.

The patient could not tolerate chemotherapy, was unsuitable for immune-check point inhibitors because the tumor had microsatellite stability, did not respond well to radiotherapy, and his case was complicated with anemia, pelvic infection, hydro-nephrosis, renal insufficiency, hypoalbuminemia, and cachexia. After a multidisciplinary team discussion, surgical extirpation was considered the most suitable treatment option. The patient was informed of the result of the multidisciplinary team discussion, including the pros and cons of the procedure, inconvenience of bilateral cutaneous ureterostomy, surgical risk, and possibility of tumor recurrence. The patient decided to undergo the operation: modular pelvic exenteration. The tumor was resected en block, with a clear resection margin. Sigmoid colostomy and bilateral ureterostomy were performed. The postoperative histological examination revealed a moderately differentiated adenocarcinoma (grade II), T4b (seminal vesicles, prostate, and bladder involved), negative resection margin, mild tumor budding, negative microvascular and peri neural invasion, lymph node metastasis (1/15), and positive gene mutations in MLH, PMS2, MSH2, and MSH6 (Figure 2).

We designed a modular pelvic exenteration approach to guarantee en bloc resection and a clear resection margin (Figure 3). Based on surgical strategy and anatomic structure, we divided the pelvis into 4 modules: the rectal module, left lateral module, right lateral module, and urinary bladder module. The boundary of the rectal module is the mesorectal fascia, which consists of the Denonvillier fascia, urinary fascia, and presacral fascia. The boundary of the urinary bladder module is the retropubic space and Denonvillier fascia. The bladder, prostate, and bilateral seminal vesicles are located in the urinary module. The boundary of the lateral module consists of the iliopsoas plane and urinary fascia plane. For this patient, all 4 modules were involved. Thus, we combined the modules and delineated the preliminary resection margin: the iliopsoas plane, retropubic plane, and presacral fascia. The operation removed all organs and tissues within the space including the iliopsoas plane, retropubic space, and mesorectal fascia, and except for the bilateral external iliac vessels and bilateral obturator nerves, achieved an en bloc resection of the entire tumor with a clear resection margin.

The specific operative steps were as follows: (1) The sigmoid colon and its mesentery were mobilized. The inferior mesenteric vessels were ligated and ampullated. The sigmoid colon was transected. The bilateral ureters were transected at their crossing with iliac vessels. (2) The anterior resection margin was along the retropubic space till to the distal end of the prostate downward, and the urethra was ligated and ampullated. (3) The posterior resection margin was along the presacral fascia till to the level of levator ani. The anal canal was resected from the perineum as a standard abdominoperineal resection. (4) The lateral resection margin was along the external iliac arteries and iliopsoas plane till to obturator foramen. The obturator nerves and external iliac vessels were preserved. (5) The specimen was removed en bloc. Sigmoid colostomy and bilateral ureterostomy were performed.

The operation lasted for 237 min, and there was a blood loss of 800 mL. During the operation, 1400 mL of packed red blood cells and 600 mL of plasma were transfused. After the operation, ertapenem was injected 1 g/day for 7 days, and albumin was injected 20 g/day for 3 days. No anticoagulation was used. There were no complications after the surgery. The bowel regained function 3 days after surgery. The patient was discharged 13 days after surgery. The postoperative histological examination revealed a moderate differentiated adenocarcinoma (grade II), T4B (seminal vesicles, prostate, and bladder involved), negative resection margin, mild tumor budding, negative microvascular and peri neural invasion, lymph node metastasis (1/15), and positive gene mutations in MLH, PMS2, MSH2, and MSH6. No further chemotherapy was administered to the patient after discharge. In the follow-ups at 6, 12, 18, and 24 months after surgery, no tumor recurrence was discovered, and the patient was in good condition, with a weight gain of 15 kg.

Discussion

EMPTY PELVIS SYNDROME:

Empty pelvis syndrome is a major contributor to morbidity following pelvic exenteration. None of the available methods have been universally successful in mitigating this problem. It has been reported that mesh reconstruction, breast pros-thesis, or obstetric balloon can be used as a pelvic spacer and reduce the risk of small bowel obstruction, entero-cutaneous fistulas, and perineal hernia [17,18]. For this patient, since infection and abscesses around the tumor had been identified by preoperative CT and MRI, we did not introduce any foreign implant for pelvic reconstruction to prevent empty pelvis syndrome. Fortunately, the patient did not have any symptoms of empty pelvis syndrome, such as perineal hernia and ileus. For selected patients, an artificial implant can be used to reconstruct the pelvic cavity and prevent empty pelvis syndrome.

BLOOD SUPPLY TO THE PELVIS:

The major blood supply to the pelvic viscera is via branches of the internal iliac arteries. The predominant blood supply to the pelvic floor is from the parietal branches of the internal iliac arteries. Bilateral internal iliac artery ligation, a life-saving procedure to control massive obstetric and gynecological hemorrhage, has been performed for over a century [19]. This procedure leads to no tissue necrosis due to ample collateral circulation in the pelvis from the major pelvic anastomosis [19]. In this patient, we resected most of the pelvic viscera. Considering the ample collateral circulation in the pelvis and the majority of pelvic organs to be removed, there was a low possibility of ischemia and necrosis. A report demonstrated the feasibility of transecting a single side of the external iliac vein [20]. The femoral vein, which drains the lower limb, continues as the external iliac vein once it crosses beneath the inguinal ligament. As a result of restricted blood flow following the obstruction of the external iliac vein, collateral pathways develop either by bypassing the obstruction to join the common iliac vein on the ipsilateral side of the obstruction via the deep external pudendal, deep circumflex iliac, obturator, and internal iliac veins or by running through the veins of the lower anterior abdominal wall [21,22]. Transection of the single-side external iliac vein can lead to chronic single-sided leg lymphedema, which can be managed with compression hosiery and regular physiotherapy. In selected patients, a radical resection, ligation of both-side internal iliac vessels with single-side external iliac veins, is safe and feasible.

PROCEDURE OPTIONS FOR RECONSTRUCTION OF THE URINARY SYSTEM:

In this case, the tumor involved most of the bladder, including the triangle area; thus, the entire bladder was resected and a bilateral cutaneous ureterostomy was performed. In appropriately selected patients, orthotopic neobladder reconstruction can preserve body image and continence, and continent cutaneous diversion represents a reasonable alternative. Conduit diversion, which remains the most performed diversion technique, is ideal for patients who would benefit from a less morbid surgical procedure that negates the need for self-catheterization [23]. The aforementioned procedure involves the use of an intestinal segment to connect the ureters and skin, which implies that further intestinal anastomosis is needed. Our patient had conditions of local pelvic infection, severe anemia, hypoalbuminemia, and cachexia. These disadvantages increase the risk of anastomotic leakage after intestinal anastomosis. Anastomotic leakage would have been disastrous to this patient’s general condition. After being told about the risk of anastomotic leakage, the patient decided to accept a safer bilateral cutaneous ureterostomy instead of an ileal conduit or neobladder. Despite the inconvenience, we respected the patient’s decision and performed a bilateral cutaneous ureterostomy.

POSSIBILITY OF REGIONAL CHEMOTHERAPY:

The ideal management for this patient was systematic chemo-therapy combined with radiotherapy and target therapy, but not surgery. As mentioned above, the patient could not tolerate systematic chemotherapy; thus, surgery was the only option. In addition to surgery, regional chemotherapy may have been helpful for this patient. Regional chemotherapy aims to directly deliver a high drug concentration to the tumor to obtain a higher drug concentration exposure than systemic chemotherapy. Some medical centers have performed regional chemotherapy by hypoxic pelvic perfusion (HPP) [24], which is a reasonably complex procedure that integrates the multidisciplinary competence of surgeons, radiologists, and perfusionists. It isolates pelvic circulation by blocking blood flow in the aorta and inferior vena cava with balloon catheters and at the thigh level with pneumatic cuffs [24–26]. Integration of HPP/ target therapy can be effective in local control as a third-line treatment for patients with unresectable recurrent rectal cancer [27]. For patients with unresectable advanced rectal cancer who cannot tolerate systematic chemotherapy, the “HPP plus” technique (HPP plus chemotherapy, HPP plus target therapy) can be an alternative treatment option. HPP plus is a regional-effected technique; thus, it is better tolerated than systematic treatment. For our patient, owing to pelvic infection, we did not adopt this technique.

APPROACH FOR THE SURGERY:

Reports have demonstrated that the robotic approach to rectal resection is a better way to obtain a complete total mesorectal excision [28]. Robot-assisted radical cystectomy has similar cancer control results but has less blood loss and a lower transfusion rate than does open radical cystectomy [29]. All things considered, perhaps our strategy could be applied by a robotic approach.

Conclusions

In this report, we described a surgical modular pelvic exenteration strategy. For those locally advanced rectal cancers with adjacent organs involved, even with frozen pelvis status, this strategy may achieve a better en bloc radical resection and a clear resection margin in selected patients. Also, survival benefit may be expected in cases of tumors with low aggressiveness.