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Management of Rectal Villous Tumors
Introduction
The rectum, which is the organ of defecation, is a unique part of the gastrointestinal tract. The anatomic and physiologic characteristics peculiar to this role allow specific and sometimes unique approaches to management of neoplasms of the rectum. This chapter discusses options for the management of benign epithelial neoplasms in the rectum.
Rectal Anatomy and Physiology
The rectum consists of the lowest 8 inches of the intestinal tract. It is normally empty and therefore does not constantly engage in peristalsis. When filled with stool by a mass movement, the rectum contracts to expel the stool. Defecation is accomplished by the reflex relaxation of the internal anal sphincter and the voluntary relaxation of the external sphincter. Sometimes when defecation is not convenient and the external sphincter remains closed, the rectum accommodates its stool, with a temporary reduction in rectal pressure and closure of the anus. After a while, the rectal pressure rises again, although defecation is never as efficient later as it is with the initial urge.
Clinically Significant Associations of Rectal Function
This requirement for the rectum to both accommodate and expel stool is associated with a complete two-layer muscular coat that acts as a safeguard against polypectomy perforation. It also produces a mucosa that is more redundant than colonic mucosa and less tightly attached to the underlying muscularis propria, and thus it is more pliable and has a greater ability to be pulled into a snare. The lack of constant peristalsis encourages the development of large sessile (villous) lesions, and the extraperitoneal position of the lower half to third of the rectum minimizes the consequences of full-thickness excision.
Therapeutic Options Resulting from the Location of the Rectum
Several options are available for obtaining access to lesions of the rectum by virtue of the location of the rectum just above the anus, in the posterior pelvis. Rectal polyps can be approached transanally, through operating proctoscopes, or by transabdominal procedures. Surgeons therefore have the choice of a number of procedures for dealing with rectal villous tumors: direct transanal excision, endoscopic polypectomy through either flexible or rigid scopes, transanal endoscopic microsurgery (TEM), transanal minimally invasive surgery (TAMIS), a Delorme mucosal strip, trans-sacral approaches, and anterior resection. The advantages and disadvantages of these options are listed in Table 27-1 .
TABLE 27-1
Options for the Removal of Villous Tumors of the Rectum
| Procedure | Indications | Advantages | Disadvantages |
|---|---|---|---|
| Endoscopic polypectomy | Benign tumor Any locations |
Can remove large tumors Low rate of complications Outpatient Inexpensive, with no special equipment required |
Piecemeal resection is common High recurrence |
| Transanal excision | Low tumor (below the lowest rectal valve) | Complete excision Low recurrence Inexpensive No special equipment required |
Can be difficult to perform Stretches the anus Requires general anesthesia |
| Transanal endoscopic microsurgery | Any tumor, including T1, T2 cancer Any location |
Complete excision Low recurrence |
Costly Equipment and training needed |
| Transanal minimally invasive surgery | Any tumor, including T1, T2 cancer Any location |
Complete excision Low recurrence |
Costly Specialized equipment and training needed |
| Delorme | Benign tumor, large and circumferential |
Low complications No anastomosis |
Difficult to perform Not possible in all patients |
| Trans-sacral | Benign tumor in mid/upper rectum No longer used |
Avoids resection | Possible parasacral fistula |
| Anterior resection | Very large, circumferential tumors Suspicious for cancer Delorme procedure not possible |
Complete clearance Cancer not a concern No recurrence |
Major surgery Hospitalization Complications Altered function |
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