Long-Term Risk of Colorectal Cancer After Negative Colonoscopy

[Hopeful]

J Clin Oncol. 2011 Aug 29;[Epub Ahead of Print], H Brenner, J Chang-Claude, CM Seiler, M Hoffmeister

This population-based study demonstrated that the risk of colorectal cancer is low following a normal colonoscopy, even in people with a family history, suggesting that, in non-smokers, screening intervals for colonoscopies might be extended beyond 10 years.

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This population-based study demonstrated that the risk of colorectal cancer is low following a normal colonoscopy, even in people with a family history, suggesting that, in non-smokers, screening intervals for colonoscopies might be extended beyond 10 years.

SUMMARY

OncologySTAT Editorial Team

Clinicians have recommended colonoscopy every 10 years to reduce the incidence and mortality of colorectal cancer (CRC), despite the lack of hard evidence to support this recommendation. The intervals between screenings and the number of necessary examinations are factors essential to cost effectiveness and patient compliance. Brenner et al undertook this long-term, observational study to assess risk estimates by time span from previous colonoscopy, gauging results by spans that ranged from 1 to 2 years up to 20+ years.

A total of 1945 patients and 2399 controls were recruited between 2003 and 2007; ultimately, 1692 patients and 1896 controls were included in the study. The investigators considered patients' gender, age, history of CRC in a first-degree relative, and smoking status (never, former, current). The mean age of participants was 69 years, and slightly more than half the participants were men. The key variable was a negative colonoscopy.

A total of 165 patients (9.7%) had a negative colonoscopy vs 693 (36.6%) of the control group participants. Significantly more patients than control subjects had a positive family history (P < .001) and smoking history (P < .001). Of the 1692 patients, 961 (56.8%) were men; 232 (14.1%) had a first-degree relative with CRC; and 264 (15.7%) were current smokers. Of the 1986 controls, 1066 (56.2%) were men; 192 (10.4%) had a first-degree relative with CRC; and 220 (11.7%) were current smokers.

Controls were four times more likely to have had a previously negative colonoscopy than patients (36.6% vs 9.4%, respectively). After adjusting for confounders, a previous negative colonoscopy was associated with a markedly reduced risk of CRC (adjusted odds ratio, 0.19; 95% CI 16–23). During the2 decades after negative colonoscopy, very low risk of developing CRC prevailed. When the group of study members with a previous negative colonoscopy was further limited to those with only one previous colonoscopy (approximately 67% of the negative colonoscopy group), risk estimates were similar.

The odds risks were lower for men (considered at higher risk of CRC), but the results held for women as well. For patients with a family history of CRC, the odds ratios (0.66 and 0.47 for intervals of 5–9 years and 10+ years) were similar to those of patients without a family history of CRC and no previous colonoscopy. Indeed, typically screening begins at a younger age for patients with a family history of CRC. The authors note that, although colorectal neoplasms are more often found at first-time colonoscopy in this group, the results suggest that, even for this group, if the first colonoscopy is negative, the screening interval might be lengthened.

The risks of CRC remained low for former and never smokers who had a negative colonoscopy, compared with former and never smokers with no previous negative colonoscopy. For current smokers, the risk was low during the first 4 years after a negative colonoscopy, but rose afterward. The odds ratio went from 0.14 for 1 to 4 years, to 0.44 for the span 5 to 9 years, but rose to 0.72 for 10+ years. Current smokers who had a negative colonoscopy 10+ years previously had a risk of CRC similar to that of never smokers who had not had a colonoscopy, 0.66.

The study's results suggest the possibility of extending the time between screenings. After a negative colonoscopy, the time could extend beyond 10 years, to as long as 20 years, even for people with a family history of CRC, as well as for men and never and former smokers. A longer interval would allow for more compliance as well as cost-effective use of screening, extending it to larger numbers of people, including those in countries with limited resources for colonoscopy.

Hopeful

[Jackie07]

Another cost-cutting measure?

I had been told by my family doctor that, with a family history of colon cancer, I needed to have a colonoscopy every 5 years instead of every 10.

Perhaps other factors need to be taken into consideration? 2nd brother found his colon cancer by himself at about stage II when he's 59. Our family cancer history (brain, breast, colon, Non-Hodgkins Lymphoma) fits the HNPCC profile. I am going to follow the 5-year advice no matter what.