The article by Drs. Wagman and Minsky is an excellent overview of the history, indications, treatment considerations, and comparative results of local excision alone and local excision plus chemoradiotherapy for selected distal rectal cancers. Although the literature and experience with local excision have increased, use of the technique has probably diminished over the past decade, primarily due to the groundswell of publications that lionize total mesorectal excision with low colorectal or coloanal anastomosis for most rectal cancers, as well as our inability to stage and predict nodal involvement, even in T1 cancers.
It is, therefore, natural for the young colorectal surgeon to promote total or near-total rectal excision for anything but the tiniest, very low rectal cancer. However, before signing up for a total mesorectal excision and coloanal anastomosis, the patient with a somewhat larger, low cancer requires a prolonged office visit to fully grasp all the issues at play here. To be fair, the physician must describe not only the possible genitourinary side effects of the surgerynowadays minimized, but not totally effaced, by careful nerve-sparing surgerybut also the decreased time from defecational signals to more urgent need. Additionally, the physician must portray the essential ignorance of nodal status (and, thus, the specter of occult nodal involvement) with anything but a total nodal excision.
Procedures to Perform Prior to Local Excision
If the patient persists in considering local excision, several options might further guide the decision:
A good transanal ultrasound exam and magnetic resonance imaging with rectal coil can be used to look for transmural extension and possible involved nodes.
If an enlarged node is seen, a transrectal ultrasound-guided needle biopsy is worth considering.
If images record questionable or no transmural invasion, one might proceed with a positron-emission tomography (PET) scan in search of hot nodes.
Assuming no nodes are imaged by PET, a full-thickness disc excision could be performed, with removal of the underlying mesorectum and lymph nodes. (If attempting a sentinel node biopsy, use very little dye, since even 1 cc stains everything and is useless.) If a node or deep margin is positive, then the decision for low anterior resection or abdominoperineal resection, probably after preoperative chemoradiotherapy, is made. If a mucosal margin is microscopically positive, a reexcisionand even re-reexcisionsof that margin can be performed.
Data clearly show that patients with positive margins will not have acceptable local control. Is it harmful to perform reexcisions in an attempt to provide clear mucosal margins? We have not found this to be so, either for local control after local excision and chemoradiotherapy or after low anterior or abdominoperineal resection following local excision attempts. With the rectum, potency, and/or continence at stake, the patient will be more satisfied if every viable alternative is explored prior to a very low anterior or abdominoperineal resection.
Anecdotal cases of T3, NX, N0, and even N1 tumors have been treated with local excision plus chemoradiotherapy. However, there have not been enough cases to provide meaningful data regarding local or systemic control rates. Similarly, the authors list 33 of 58 cases of recurrence in which long-term salvage was achieved by low anterior or abdominoperineal resection. These data, however, were not prospectively collected, so the real salvage rate is probably considerably less.
It is unlikely that a randomized trial of local excision vs low anterior resection or abdominoperineal resection could ever be carried out, because patients would not accept the more extensive extirpational procedures if they thought the two therapies might actually be of equal value for a given tumor. Clearly, certain cancers are best treated by local excision with or without radiation therapy and others are best treated by abdominoperineal or low anterior resection with or without radiation therapy. For a third group of tumors, however, the preferred operative approach exists in a zone of uncertainty. We must strive to correctly group our patients and to develop techniques that will reduce the numbers of this third cohort.
To this end, we need to develop trials to help find chemoradiotherapy regimens with more efficacy and less toxicity, as well as trials looking for better staging techniques (eg, sentinel node biopsy, limited lymphadenectomy with local excision, PET scanning). We have all noted complete pathologic responses to chemoradiotherapy. One wonders if preoperative chemoradiotherapy might improve tumor control with local excision procedures. Potential dangers include poorer wound healing and the fact that the tumor site may be overlooked after a major or complete response. To avoid the latter, the tumor boundaries should be tattooed prior to instituting therapy.
Given our inability to complete trials of chemoradiotherapy sequencing in this country, it is doubtful that we will be able to assess the value of preoperative adjuvant therapy vs postoperative therapy in a phase III trial. Furthermore, no staging method is as accurate as an intact surgical specimen. Since there is no difference in the position of the small bowel before and after transanal excision, the appeal of preoperative chemoradiotherapy in this setting is not as great as it is prior to larger excisional procedures of the rectum. Thus, the only theoretical advantage of preoperative (vs postoperative) chemoradiotherapy is its 4- to 6-week earlier delivery.