Local Excision in Rectal Cancer: Not What It’s Cut Out’ To Be?
ABSTRACT & COMMENTARY
Synopsis: Local excision in rectal cancer may be associated with a higher recurrence rate than previously reported. Garcia-Aguilar and colleagues review their experience with 82 patients.
Source: Garcia-Aguilar J, et al. Ann Surg 2000; 231:345-351.
In this interesting study from the university of Minnesota Cancer Center, Garcia-Aguilar and associates retrospectively identified 82 patients who underwent a transanal excision of a rectal cancer with a curative approach. Patients were excluded from the analysis for the following reasons: tumor excised by snare polypectomy, positive margins, poorly differentiated histology, presence of mucinous component, or lymphovascular invasion. Importantly, the analysis did not include patients treated with chemoradiotherapy or T3 disease (invasion into the perirectal fat). Seventy-two percent underwent preoperative endorectal ultrasound (ERUS).
Of the 82 patients, 55 had T1 and 27 had T2 disease. Both the average age of 67 years and average distance from the anal verge of 6.2 cm were similar in patients with T1 and T2 disease. The overall recurrence rate was 24% (18% for T1 tumors and 37% for T2 tumors) with an average time to recurrence of 18 months for both groups. For T1 tumors, there were 10 recurrences, nine of which were local only. For T2 tumors, there were also 10 recurrences, eight of which were local only. Most patients with a local recurrence underwent a second surgical procedure. There were 20 deaths in this study although all but three were from unrelated causes.
Garcia-Aguilar et al examined the accuracy of the preoperative ultrasound. Of 26 tumors deemed to be T1 by the ERUS, five (19%) turned out to be pathologically T2. Of the 19 tumors deemed to be T2 by the ERUS, five (26%) were found to be T1 at the time of surgery.
COMMENT BY KENNETH W. KOTZ, MD
The role of ERUS for staging and follow-up was examined by Garcia-Aguilar et al. ERUS appears to be helpful in identifying who is a candidate for local excision by eliminating those patients with invasion into the perirectal fat. However, in this study, ERUS did not reliably differentiate between T1 and T2 tumors. On the other hand, ERUS was useful for detecting local recurrences. By performing ERUS and proctoscopy every four months for three years, then every six months for two years, Garcia-Aguilar et al were able to detect half of the recurrences at a scheduled follow-up visit.
Local excision is an attractive alternative to radical proctectomy because of fewer perioperative complications and avoidance of a permanent colostomy. As Garcia-Aguilar et al point out, it is generally accepted that candidates for local excision must have moderately or well-differentiated T1 or T2 tumors, no lymphatic/vascular invasion, no mucinous component, and negative postoperative margins. Other important features for the successful use of local excision include tumor size less than 4 cm in diameter and involvement of less than 40% of the circumference. It is also preferable for tumors to be mobile, non ulcerated, and located posteriorly. Despite eliminating patients with high-risk features from their analysis, the recurrence rates of 18% and 37% for T1 and T2 tumors, respectively, seemed higher than expected.1
So, what postoperative therapy should an oncologist recommend for a patient who has undergone local excision for rectal cancer? These results notwithstanding, T1 tumors with low-risk features have a low incidence of relapse, and, therefore expectant observation is appropriate for these patients.2-4 How to approach a high-risk T1 tumor after a local excision is unknown but could include radical excision or chemoradiotherapy.4-5 T2 tumors with low-risk features are usually approached with postoperative chemoradiation.3-5 In the study by Garcia-Aguilar et al, there were a few systemic recurrences. Whether there is a subgroup of T1 or T2 patients who, without nodal information, can be determined to be at sufficiently high risk of systemic relapse to justify adjuvant chemotherapy after chemoradiation is unknown. Finally, although many patients with a local failure can be salvaged by radical excision, the results of Garcia-Aguilar et al remind us that the integration of local excision into the treatment of rectal cancer should continue to be evaluated.
References
1. Garcia-Aguilar J, et al. Ann Surg 2000;231:345-351.
2. Weber T, et al. Oncology 1998;12:933-943.
3. Marcet J, et al. Cancer Control 1996;3:26-33.
4. Willett C, et al. ASCO Educ Book 1999;212-221.
5. Hoffman J. Oncology 1998;12:944-947.
In the study by Garcia-Aguilar et al, what percent of tumors which by preoperative endoscopic ultrasound appeared to be T1 were found to be pathologically T2?
a. 5%
b. 9%
c. 19%
d. 26%
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