Flexible sigmoidoscopy screening less beneficial in older women

Last Updated: 2017-01-23

By Will Boggs MD

NEW YORK (Reuters Health) - Flexible sigmoidoscopy screening reduces the incidence of colorectal cancer and colorectal cancer mortality to a greater extent in men and younger women than in older women, according to a pooled analysis of randomized trials.

"It is very important to stress that flexible sigmoidoscopy is an effective screening tool for men," Dr. Oyvind Holme from Sorlandet Hospital Kristiansand in Norway told Reuters Health by email. "It requires minimal preparations from the patients, can be done without sedation and is quick and seldom associated with significant discomfort. For older women, we think that other screening methods should be considered."

Flexible sigmoidoscopy has been shown to reduce both the incidence of and mortality from colorectal cancer, but whether the effects of screening differ in younger versus older individuals and in women versus men is unknown.

Dr. Holme's team used data from three large-scale randomized trials - PLCO, SCORE, and NORCCAP - to investigate the impact of sex and age on the effectiveness of flexible sigmoidoscopy screening.

Among men, flexible sigmoidoscopy screening was associated with a significant 24% reduction in the incidence of colorectal cancer, with no difference between age groups.

Colorectal cancer incidence was also significantly reduced in women, by 17%, but the effect was confined to younger women. For women 60 years and older, there was only a small (10%), statistically nonsignificant effect of screening.

Flexible sigmoidoscopy reduced the incidence of colorectal cancer in the distal colon to a similar extent in men and women and in older and younger age groups, the researchers report in The BMJ, online January 13.

In contrast, the incidence of colorectal cancer in the proximal colon was significantly reduced in men and younger women, but not in older women.

Colorectal cancer mortality was reduced by 27% in men and by 18% in women, but when the analyses were restricted to the 55-64 year age group, colorectal cancer mortality was statistically significantly reduced in men and younger women, but not in women aged 60 years and older.

"We show that there is a difference between men and women in effectiveness of flexible sigmoidoscopy," Dr. Holme concluded. "There has been one similar report for guaiac-based FOBT (fecal occult blood test). Nowadays, immunochemical fecal tests (FIT) or colonoscopy are the most popular tools for CRC screening, although there are no published randomized trials that prove their effectiveness in CRC screening."

"We don't know whether a sex/age difference exists for FIT or colonoscopy," he said. "We think it is important to evaluate these issues in future randomized screening trials and not just implement screening in a population. After screening has been implemented in a population, evaluation of its effectiveness is very difficult."

Dr. Ulrike Haug from Leibniz Institute for Prevention Research and Epidemiology-BIPS and the University of Bremen, Germany, who wrote an accompanying editorial, told Reuters Health by email, "In the light of the study's findings, recommending flexible sigmoidoscopy screening to women seems no longer tenable. Whether it should be combined with or replaced by other screening tools among women of this age remains to be clarified."

"There is good and bad news," she said. "Screening flexible sigmoidoscopy has been shown to be an effective screening tool in men irrespective of age and also in women younger than 60. But unfortunately, it is currently not clear what to recommend to women aged 60 and older. Colonoscopy might be an option, but this is a complex issue for decision makers."

Dr. David Lieberman from Oregon Health and Science University in Portland, who has written extensively about colorectal cancer screening, told Reuters Health by email, "I believe the report emphasizes the importance for customization of screening based on age and gender."

"Younger women may need less-intensive forms of screening due to low risk (FIT, flexible sigmoidoscopy), whereas older women may benefit from programs which can identify proximal colon lesions," he said. "For men, the age-adjusted risk of colorectal cancer is much higher than women even at a younger age, and more-intensive screening may be warranted at any age above 50. For both men and women, advancing age is associated with higher risk of proximal pathology, and programs which can identify proximal colon pathology may be preferred."

Dr. Martin C. S. Wong, director of The Chinese University of Hong Kong's Bowel Cancer Education Center, told Reuters Health by email, "Physicians should recommend colorectal cancer screening modalities based on an individualized approach, taking into account subjects' age and gender. Women aged 60 years or older may consider alternative screening strategies, like colonoscopy or fecal immunochemical test."

"Future studies should be performed to externally validate the present findings, and examine the acceptability of this risk-stratification strategy in population-based screening programs," he said.

SOURCE: http://bit.ly/2jQjtF4 and http://bit.ly/2jhio8r

BMJ 2017.