Indications for Extended Resection
Approximately 5% to 8.8% of patients who present with colorectal cancer will have tumors that spread beyond the anatomic landmarks of a standard TME resection., T4 tumors have a worse overall prognosis, and decision-making for these patients must be multidisciplinary and highly individualized. For patients who are fit enough to undergo aggressive treatment and willing to accept a high degree of treatment-related morbidity, curative-intent treatment may be pursued. In this context, the most important goal in surgical planning is obtain a histologically negative margin (R0 resection), even if resection of multiple organs and structures is required to do so.
Care of these patients begins with a thorough, patient-specific evaluation including imaging, medical evaluation, preoperative counseling of functional expectations, and potential stoma counseling and education. The extension of tumor beyond the confines of the mesorectum is best assessed by magnetic resonance imaging (MRI). Once identified, these patients require care from a multidisciplinary team, with surgical (e.g., colorectal surgery, gynecology, neurosurgery, orthopedic surgery, plastic and reconstructive surgery, spine surgery, urology), oncology, radiation oncology, radiology, and pathological expertise and experience in pelvic exenteration. Nearly all patients with these more locally-advanced primary tumors (beyond the normal TME planes) undergo chemoradiation therapy prior to surgery.
Optimal patient selection begins with a thorough assessment of the patient’s performance status and overall health. Those individuals with significant functional impairments and comorbidities are often not considered acceptable surgical candidates. The patient’s emotional preparedness for undergoing this extensive treatment should be evaluated. He/she should be well informed of the functional effects of the planned surgery as well as the short- and long-term risks of complications.
The next step in this process requires the assessment of the anatomical relationships of the tumor and its potential involvement of adjacent pelvic organs and structures. The primary goal of surgery is the achievement of an R0 resection, that is, resection with histologically negative margins. Surgical planning with the aid of a high-resolution MRI can best plan for the required resection of the potentially involved structures and insurance of an en bloc resection. A PET-CT scan in addition to the usual CT scan of the chest, abdomen, and pelvis may aid in the detection of occult extra pelvic disease. This imaging modality may assist in excluding patients from futile radical resections in attempts at cure.
The presence of any metastatic disease complicates the decision to pursue pelvic exenteration. Extensive metastatic disease is a contraindication to exenteration; however, patients with limited metastatic disease may be considered for extensive surgery. The role of a multidisciplinary tumor conference is essential in establishing a patient-specific treatment plan. All patients with locally advanced rectal cancer are referred for neoadjuvant chemoradiation therapy. Multimodality therapy including external beam radiation therapy and neoadjuvant/adjuvant chemotherapy and potential intraoperative radiation therapy (IORT) are considered in maximizing local control and improving patient survival. Although there are inherent limitations of post-treatment imaging, patients with these types of tumors should generally be rescanned after completing treatment prior to surgery.
The contraindications and limitations of resectability are debated, and these limitations concentrate on the ability to achieve an R0 resection with an acceptable risk for postoperative morbidity. However, these decisions are best made at experienced centers with the appropriate expertise in pelvic exenteration.
There are four main anatomical categories of tumors requiring extended proctectomy:
- Axial tumors involve the central pelvic organs and do not invade the anterior, posterior, or lateral pelvic walls.
- Anterior tumors invade the bladder, vagina, uterus, seminal vesicles, and/or prostate.
- Posterior tumors invade the sacrum and/or coccyx
- The most challenging are lateral tumors, which involve the bony pelvic side wall or side-wall structures, including the iliac vessels, pelvic ureters, lateral lymph nodes, pelvic autonomic nerves, and side-wall musculature.
Pelvic exenteration surgery can be described using these anatomic regions, for example "anterior exenteration" for rectal cancer involves excision of the rectum and mesorectum en bloc with anterior structures (Figure 6.1).
The contraindications to pelvic exenteration are patient preference, lack of appropriate fitness, inoperable metastatic disease, and tumor extending to the S1 level of the sacrum. The relative contraindications are distant metastases, metastases to para-aortic lymph nodes, and tumor fixed to more than one non-axial pelvic structure. It is institution-dependent if lateral recurrences are a contraindication to a pelvic exenteration. Many perform this surgery with experienced teams after careful assessment of what would be required for en bloc resection to attain a R0 resection. Evidence of bilateral ureteral obstruction may be associated with involvement the bladder trigone or bilateral pelvic sidewall infiltration.
Preoperative enterostomal therapist counselling for marking and education is critical to the successful postoperative outcomes associated with the potential need for a colostomy and/or urostomy. Urological consultation for placement of ureteral stents is helpful in assisting in identification of the ureters and their potential involvement in the required resection. Plastic and reconstructive surgical consultation for perineal defect reconstruction is essential in minimizing risks of wound complications. The options include a rectus myocutaneous flap, gracilis muscle flap, gluteal rotational flap, free flap, or biological mesh with omentoplasty.
It is critical in successful planning for a pelvic exenteration to include a discussion regarding functional outcomes and expectations. These include the quality of life changes associated with a potential colostomy, urostomy, and compromise to pelvic nerves including bowel, sexual, and urinary dysfunction.
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