Sphincter preservation in rectal cancer–continued evidence of success

Abstract

Improvement in local control and survival are the primary goals of most clinical trials in rectal cancer. Although these are important measures of success, there are other equally important endpoints. These include sphincter preservation, sphincter function, and quality of life. In our quest to improve survival, we sometimes overlook these endpoints. The three broad approaches in which adjuvant therapy has been used to enhance sphincter preservation include radiation therapy alone, preoperative therapy followed by a coloanal anastomosis or a local excision, and a local excision followed by postoperative therapy. There is much confusion in the literature regarding the best approach. In some clinical situations, more than one approach may be acceptable. Their selection depends on factors such as tumor histology, size, location, mobility, anatomic constraints, intercurrent medical disease, and the technical expertise of the surgeon and radiation oncologist. Just as practice, practice, and practice is the way to Carnegie Hall, selection, selection, and selection is the key to success in sphincter preservation. Most series carefully select patients, thereby making it difficult, in the absence of a randomized trial, to accurately compare the results of these different approaches. Given the morbidity of standard surgery, as well as the frequent need for adjuvant therapy, the use of the conservative approach of local excision plus postoperative adjuvant therapy as primary therapy for selected cases of rectal cancer is appealing. This approach has been successful in other anatomic sites such as breast cancer and sarcomas of the extremities. In the rectum, it offers an opportunity for sphincter preservation. In this issue of the International Journal of Radiation Oncology, Biology, and Physics, Russell and colleagues from the Radiation Therapy Oncology Group (RTOG) report the long-term results of RTOG 89-02. In this Phase II trial, 65 patients with adenocarcinoma of the rectum underwent a local excision and were selected to receive one of three postoperative therapies, depending on the presence of adverse pathologic features (defined as T2-3 disease, highgrade, the presence of vascular or endothelial-lined space invasion, an elevated CEA, or positive margins). The 14 patients with negative margins and no adverse features underwent observation only. The 18 patients with negative margins but with other adverse features received two monthly cycles of continuous infusion 5-FU concurrently with 45–50.4 Gy to the pelvis followed by a boost, to a total dose of 50–56 Gy. In the 33 patients with positive margins (with or without adverse features), the boost dose was increased to 59.4–65 Gy. The RTOG 89-02 trial served as the precursor to the Intergroup CALGB 8984 trial (1). Both of these trials confirm that this approach is feasible in a multi-institutional, cooperative group setting. There are a number of questions regarding the use of local excision and postoperative therapy. For example, are the results comparable with an abdominoperineal resection (APR), what features are helpful in identifying the ideal treatment approach, are the functional results acceptable, and is there a role for combining chemotherapy with radiation? This RTOG 89-02 trial, together with other series, provides some answers to these questions. The local failure rates in the RTOG 89-02 trial are consistent with other series (2). Of the 51 patients who received postoperative combined modality therapy, 14% developed a local failure, which is similar to the 12% reported in other series. The increase in local failure by T stage (T1: 4%, T2: 16%, and T3: 23%) is also consistent with other series: T1: 5%, T2: 14%, and T3: 22%. Local failure rates with local excision and postoperative therapy are higher than those reported with radical surgery. On a positive note, most local failures occur at the anastomotic site and not in pelvic lymph nodes (3). Furthermore, salvage of local failures is possible. In the RTOG 89-02 trial, 63% of patients with local failure were salvaged with an APR. Most series report that at least half of the patients who undergo a salvage APR are cured (1, 3–5). Likewise, the 5-year actuarial survival in the RTOG 89-02 trial is 77%, which is comparable to the 80% average 5-year actuarial survival rate (range 70–94%) reported in