Conservative management of early rectal cancer

Abstract

Conservative management of rectal cancer is one of the most exciting areas of clinical research in gastrointestinal cancers. The use of endocavitary radiation for early rectal cancers has been popularized by Papillon. Gerard and colleagues have continued this work and, in this issue of ZJROBP, present a well written, thoughtful analysis of their experience with this technique (3 ) . In their report, 101 patients with clinical stages Tl-2 adenocarcinoma of the distal rectum were treated with endocavitary radiation. In 28 patients whose tumors did not respond adequately, an 19*Ir implant was added. The patients were carefully followed for a median of 61 months. Those who developed a local recurrence underwent salvage surgery, which in most cases, was an abdominoperineal resection. Tumors were staged acco&ng to the St. Marks Hospital clinical staging system, and in 36 a transrectal ultrasound was also performed. The crude local/regional fail= rate (in-field and/or pelvic node failure) for the 65 clinical Tl tumors was 7% and for the 36 clinical T2 hmors was 40%. In the subset of patients who were staged with transmctal ultrasound, the crude local/regional failure rate for the 22 ultrasound Tl tumors was O%, and the 14 T2 tumors was 40%. The actuarial 5-year survival was 83% and the disease specific survival was 94%. The treatment was well tolerated. Although 27% developed ulceration of the rectal mucosa, most were asymptomatic and only six patients required steroids and all six had healing of the ulcer with no late sequela. An additional 46% had intermittent mild rectal bleeding for a median duration of 23 months. A weakness of this report is the absence of a sphincter function analysis. Sphincter preservation without adequate sphincter function is not meaningful. In addition, it should be emphasized that 28 patients received an 19*Ir implant with either a perineal or endorectal “fork” technique. Therefore, the data should not be interpreted as the results of treatment with endocavitary radiation alone. What have we learned from these data and do they change the standard of care for the management of early rectal cancers? The data suggest that in favorable early rectal cancers (transrectal ultrasound stage Tl ) , endocavitary radiation with or without an 19*Ir implant results in excellent local/ regional control and survival. Another interesting aspect of the study is the impact of transrectal ultrasound for staging early rectal cancers. I agree with the authors that transrectal ultrasound is essential for the selection of patients treated with this nonoperative technique. It is more accurate than clinical staging systems. If endocavitary radiation is to be used, transrectal ultrasound staging should be required. There are two major limitations of the endocavitary technique. First is the tumor location. Because treatment is delivered in the knee-chest position, most patients selected for endocavitary radiation usually have tumors that are limited to the anterior rectal wall. Second, few radiation oncologists are trained in the technique of endocavitary radiation and the contact radiation machine is not routinely available. How do the results of endocavitary radiation compare with other conservative treatment techniques? The difficulty with comparing the results is the wide variation of the definition of favorable vs. unfavorable early rectal cancer among the series. Each investigator uses different selection criteria, which makes interpretation of the data confusing. There is no “right or wrong” definition. Each investigator’s definition is supported by his or her data. Our previously published definition for favorable early tumors includes small ( =Z 3 cm), exophytic, mobile Tl tumors without adverse pathologic features (high grade, blood or lymphatic vessel invasion, or signet ring cell histology ) (8 ) . These represent 3%-5% of rectal cancers and can be adequately treated with a variety of local therapies such as local excision alone, cryosurgery, electrocoagulation, transrectal endoscopic microsurgery, or endocavitary radiation. Unfavorable early tumors include