PHOENIX – Improving cancer-specific survival after resection for colorectal cancer may be as simple as ordering preoperative mechanical bowel preparation, according to an analysis of data from a randomized trial conducted in Sweden and Germany.
Roughly half of the 841 patients studied had such preparation before their operation. The actuarial 5-year rate of cancer-specific survival was about 8% higher in this group, first author Dr. Åsa Collin of Uppsala University reported at the annual meeting of the American Society of Colon and Rectal Surgeons.
Dr. David Maron
An analysis of cancer stage at the time of surgery suggested that the two groups were well matched on this measure. Preparation did not significantly decrease the rate of recurrence or increase the rate of overall survival.
Session attendee Dr. J. Daniel Stanley of University Surgical Associates in Chattanooga, Tenn., questioned whether the patients might have differed on other factors that influenced whether they underwent mechanical bowel preparation.
"Were some of them obstructed, which might indicate a different tumor biology than was reflected in the staging?" he asked.
"These were all elective surgeries, and there was no patient who we actually decided that they shouldn’t have preparation," Dr. Collin replied.
In an interview, session comoderator Dr. David Maron, a colorectal surgeon at the Cleveland Clinic in Weston, Fla., said, "What was interesting was that they didn’t show a significant difference in cancer recurrence, although it was close to significance. So the question remains, is it in fact the mechanical bowel prep, or could there be differences in the postoperative follow-up and even the postoperative treatment of those patients who developed recurrence?"
Guidelines leave preparation up to the treating surgeon, and several studies have found no benefit at least in the short term, he noted. "This is one of the first studies that have shown that perhaps from a long-term standpoint in patients with cancer, that there may be some benefit to preoperative preparation of the bowel, although again, it’s preliminary and there’s a lot of unknowns out there."
Dr. Collin and her colleagues analyzed data from a trial among patients who underwent an elective resection for cancer, adenoma, or diverticular disease of the colon at 21 hospitals in Sweden and Germany between 1999 and 2005.
Earlier results for the entire trial population, previously reported, showed no significant reduction in 30-day rates of complications with mechanical bowel preparation (Br. J. Surg. 2007;94:689-95).
The new, long-term results for just the 841 patients with colorectal cancer – 53% of whom had a mechanical bowel preparation before their surgery – indicated those undergoing this preparation had a higher actuarial 5-year rate of cancer-specific survival (90% vs. 82%; P = .03).
The two groups were similar in terms of the 5-year rate of recurrence (80% vs. 89%, P = .08) and overall survival, Dr. Collin said.
"We looked at tumor stage to see if the explanation for patients having no mechanical bowel preparation having poorer cancer-specific survival was that they had more advanced tumors, and there was no difference in the stages" between groups, she said, with the majority of patients in both groups having stage II or III disease.
Dr. Collin disclosed no conflicts of interest related to the research.