Long-term functional results of radiation after coloanal anastomosis

Long-term functional results of radiation after coloanal anastomosis¹

Mathias CAC

Pemberton JH

Wolff BG

Dozois RR

Nelson H

Young-Fadok TM

Devine RM

Nivatvongs S

Mathison S

Larson D

Ilstrup D

Mathias CAC, Pemberton JH, Wolff BG, Dozois RR, Nelson H, Young-Fadok TM, Devine RM, Nivatvongs S, Mathison S, Ilstrup D, Larson D. Long-term functional results of radiation after coloanal anastomosis. Acta Cir Bras [serial online] 1999 Oct-Dec;14(4). Available from: URL: http://www.scielo.br/acb.

SUMMARY: Surgery is the only treatment that can cure most patients with colorectal cancer. Radiation therapy (pre or postoperative) has been shown to improve results by decreasing local recurrence and improving survival. Our aim was to analyze whether postoperative radiation influenced long-term functional outcomes and the probability of stricture of anastomosis in patients who underwent coloanal anastomosis for rectal cancer. Methods: The records of 84 patients with coloanal anastomosis for rectal cancer were studied between 1980 and 1996. There were 82 males and 28 females. Mean age was 57.8 years (range 24 to 78 years). Mean distal resection margin was 2.6 cm (range 0 to 14cm). Twenty-three patients received postoperative irradiation therapy. Patients who received chemotherapy were not included in the study. Results were analysed by examination , telephone or questionnaire. Mean follow-up was 3.8 years (range 0 to 13 years). Results: There was no operative mortality. Functional variables were much better in non-irradiated patients. The irradiated group had more number of stools/day (p>0.05), more number of stools/ night (p>0.05), more incontinence/day (p<0.05) and more incontinence/night (p<0.05). Irradiated patients also wore more pads (p<0.05) than non-irradiated patients. The probability of remaining free of stricture at 5 years was slightly better in non-irradiated (72 percent) than in irradiated patients (65 percent, p>0.05). Conclusion: Postoperative irradiation after colo-anal anastomosis for rectal cancer is safe, but may increase the risk of stricture of anastomosis and does affect functional results adversely.

SUBJECT HEADINGS: Anastomosis, Surgical. Irradiation. Radiation effects.

INTRODUCTION

Since Roentgen discovered the X ray, ionizing radiation has been used as a major tool against cancer . Improvements in precision and dosimetry in new machines allow better treatment techniques which can be tested accurately in prospective and retrospective clinical trials. There are a great number of studies demonstrating a pelvic failure rate after surgery alone in the treatment of rectal carcinoma from 20% to 50% or even more (1-3).

The tolerance of the GI tract limits the amount of radiation that can be directed at the pelvis. Micrometastasis or subclinical disease within the pelvic tissues should respond to 5000 cGy; however , gross or bulky disease requires highter doses (4). Endocavitary radiation and implantation of radiation sources locally would allow highter doses , but these are useful only in a small group of selected patients (5).

There are potential benefits with the use of radiation as adjuvant therapy for rectal cancer. In addition to improving locoregional control and resectability, thus improving the quality of life , its ultimate goal is to improve long-term survival (6). This latter achievement is still controversial and, if radiation does improve survival , it is not clear that it is the radiation alone that does this. The surgeon and the radiation oncologist must be a team that individualize treatment for each patient with rectal cancer.

At least one study has shown early and late effects of radiation on the anal sphincter itself (7). The purpose of this study was to analyse whether postoperative radiation influenced long-term functional outcomes and stricture in patients who underwent coloanal anastomosis for rectal cancer.

METHOD

Between 1980 and 1997, the records of 84 patients undergoing coloanal anastomosis for rectal cancer were reviewed. Mean age was 57.8 (range 24 to 78 ). There were 82 men and 28 women. Mean distal resection margin was 2.6 cm (range 0 to 14 cm). Twenty-three patients received postoperatory radiation as adjuvant therapy alone, usually initiating 5 to 6 weeks after surgery. The rest of the patients underwent only surgery (non-radiated group). Conventional doses (50 - 54 Gy) and techniques of pelvic radiation therapy were used. Patients who also received chemotherapy were not included.

Postoperative mortality was defined as death within one month of operation. Functional evaluation was assessed clinically by asking the patients about bowel frequency (day/night), incontinence (day/night) and use of pad.

Functional outcomes, represented by discrete variables, were compared using Chi-square tests. Outcomes represented by continuous variables, which were found to be sufficiently Gaussian, were analysed using t-tests. If these variables were not Gaussian, then the rank sum tests were used.

Follow-up was conducted by examination, telephone or questionnaire.

Mean time of follow-up was 3.8 years (range 0 to 13 years).

Informed consent was obtained from the patientsand approval from the Institutional Review Board at the Mayo Clinic.

RESULTS

There was no operative mortality.

The probablity of remaining free of stricture of anastomosis at 5 years was 65.2 for the irradiated group and 72.3 for non-irradiated patients (table I). However, this difference was not statistically significant (p>0.05).

Irradiation adversely affected functional outcomes. Patients with irradiation had more number of stools/ day , more number of stools/ night, more frequent incontinence /day , more frequent incontinence/ night, and also wore more pads than non-radiated patients (tables II to V)..

DISCUSSION

The frequency of locoregional recurrence after surgery in the treatment of rectal cancer has caused many pre and/or postoperative pelvic irradiation.There are many studies demonstrating that the pelvic failure rate after surgery alone increased from 20 % to 50% or more if tumor penetrated the muscle wall of the rectum or pelvic lymph nodes (1-3).

It is difficult to compare, stage for stage, the results of preoperative versus postoperative radiation therapy because preoperative trials usually include a limited number of patients with T1,2 N0 disease, and full dose preoperative radiation will downstage both the T and N stage, and patients with pathologically confirmed M1 disease are excluded from adjuvant trials (8). The only randomized trial of preoperative versus postoperative radiation therapy for resectable rectal cancer was reported by Pahlman and Glimelius (9). Patients who received preoperative radiation therapy had a significant decrease in local recurrence (13% vs 22%, p=0.02), but there was no difference in the 5-year survival rate (42% vs 38%). A significant increase occurred in the incidence of perineal wound sepsis in the preoperative group (33% vs 18%, p < 0.01).

The combination of postoperative radiation therapy and 5-fluoracil has been compared with radiation alone and has been shown to improve survival and further decrease local recurrence (10,11 ).

Nonrandomized and retrospective studies have reported the impact of postoperative therapy on sphincter function (7,12). Our own results revealed that Irradiated patients presented more stools per day and night, more frequent incontinence per day and night, and also wore more pads. The clinical effects of postoperative radiation are partly the result of decreased rectal capacity and compliance. However, changes in rectal motor and sensory function and changes to the surrounding soft tissues may contribute. Kollmorgen (12) evaluated the impact of postoperative combined modality therapy on bowel function in patients who received pelvic irradiation therapy and 5FU- based chemotherapy. Patients who received adjuvant therapy had a significant increase in the number of bowel movements and wore more pads when compared with patients who underwent operation alone. Sphincter function after a coloanal anastomosis was reported by Paty (7). Those patients who received preoperative radiation therapy, postoperative radiation therapy (with or without chemotherapy), or both, after a coloanal anastomosis, had increased stool frequency when compared with patients who underwent surgery alone.

Although the short-term toxicity of radiation therapy has been examined in previous trials (13), assessment of long-term toxicity has rarely been noted (14). Our mean follow-up period was 3.8 years (range 0 to 13 years). The probability of having a stricture of anastomosis, at 5 years, was greater in the irradiated group of patients (34.8%) than in the non-irradiated group (27.7%), however our sample size did not show a significant difference between the groups. The true incidence of radiation related complications is not known, but complications rates are quoted as low as 0.5 percent and as high as 36% (15). The incidence of clinically significant radiation related complications is approximately 5%. Conventional doses of radiation were used in this study. Radiation damage linearly correlates with the total radiation dose delivered. Anastomotic stricture, a long-term complication, though ocurring in 25 % of our patients, was not significant.

CONCLUSION

Our study indicates that postoperative irradiation is safe , but may increase the risk of stricture and does affect stool frequency adversely.

Address for correspondence:

Carlos Augusto Mathias

Av. Rosa e Silva, 295/702

52020-220 Recife – PE

Data do recebimento: 18/04/99

Data da revisão: 02/05/99

Data da aprovação: 20/06/99

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Publication Dates

• Publication in this collection
  14 Jan 2000
• Date of issue
  Oct 1999

History

• Reviewed
  02 May 1999
• Received
  18 Apr 1999
• Accepted
  20 June 1999