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Could screening for colorectal cancer be harmful? 12
THE AMERICAN JOURNAL OF GASTROENTEROLOGY © 2002 by Am. Coll. of Gastroenterology Published by Elsevier Science Inc.
Vol. 97, No. 1, 2002 ISSN 0002-9270/02/$22.00
WORLD LITERATURE REVIEW Editor: David Johnson, M.D., F.A.C.G. REVIEW PANEL Luis Balart Jamie Barkin David Bjorkman Cedric Bremner Randall Burt Harold Conn Jack DiPalma Hashem El-Serag M. Brian Fennerty
Mark Flemmer Christopher Gostout Robert Hawes Jorge Herrera Brenda Hoffman Kelvin Hornbuckle Doug Howerton Sunanda Kane
Could Screening for Colorectal Cancer Be Harmful? Hoff G, Thiis-Evensen E, Grotmol T, et al. Do Undesirable Effects of Screening Affect All-cause Mortality in Flexible Sigmoidoscopy Programmes? Experience From the Telemark Polyp Study 1983–1996 Eur J Cancer Prev 2001;10:131–7
ABSTRACT There is substantial evidence for the beneficial effect of screening programs aimed at reducing mortality from colorectal cancer. The effect on all-cause mortality, however, may not necessarily be beneficial. In this small randomized trial (n ⫽ 799), colorectal cancer incidence was reduced 80% among subjects undergoing screening flexible sigmoidoscopy with colonoscopy follow-up and surveillance over 13 yr for subjects with polyps at initial screening. The all-cause mortality was higher, however, among subjects in the screened group, mainly because of an excess of cardiovascular deaths. This study evaluated the long term effects of informing participants about findings at flexible sigmoidoscopy screening. There were no severe complications, and there was no long term difference in deaths related to whether there had been any mucosal rupture (biopsy or snare resection). As a group, those who were informed that they had polyps tended to improve their smoking habits more than those informed that they had no polyps. The group with polyps had a trend toward a smaller increase in body mass index (⫹0.7 [95% CI ⫽ 0.2–1.1]) than the polyp-free group (⫹1.2 [95% CI ⫽ 0.9 –1.6]) (p ⫽ 0.07). The authors suggest that flexible sigmoidoscopy screening may be associated with unfavorable lifestyle changes among screenees without polyps, an effect that may more than outweigh the beneficial effect of screening. (Am J Gastroenterol 2002;97:198. © 2002 by Am. Coll. of Gastroenterology)
COMMENT Ample evidence supports screening for colorectal cancer in terms of decreased colorectal cancer incidence and mortal-
Philip Katz Timothy Koch Mark Lawson Theodore Levin Edward C. Oldfield III David Ott C. S. Pitchumoni K. Rajender Reddy
Douglas Rex Arvey Rogers Richard Sampliner Paul Souney Christina Surawicz Nimish Vakil Harlan Vingan Maurits Wiersema
ity. The principal trade-offs between tests have been the increased sensitivity of more invasive tests (colonoscopy) compared with the decreased risk of immediate complications with less invasive tests (such as fecal occult blood test and flexible sigmoidoscopy). There is one concern that should give at least some pause to those of us who advocate for colorectal cancer screening: the lack of evidence for a decrease in all-cause mortality in people who are screened. There are at least two possible explanations for this observation. First, colorectal cancer accounts for a relatively small proportion of the overall mortality among screening-aged people, with cardiovascular death accounting for the lion’s share. If colorectal cancer screening has no effect on cardiovascular death, then any decrease in colorectal cancer mortality is overshadowed by the substantial impact of cardiovascular disease on overall mortality. This small study raises the potential of another, more ominous explanation—namely, that colorectal cancer screening may actually cause an increase in cardiovascular death outweighing any benefits of screening. The principle limitation of this study is the lack of data collection among controls; therefore, any conclusions drawn should at best be considered “preliminary.” In addition, the differences found in the screened group between those with polyps found and those without polyps were not significant for smoking (p ⫽ 0.10) or for body mass index (p ⫽ 0.06), when both improving and worsening were combined. The important comparison, for which these risk factors are surrogates, is mortality, and there were no mortality differences between those with polyps and those without. Despite these limitations, it will be important for future studies of colorectal cancer screening to attempt to explain the relationship between screening and cardiovascular mortality, if such an association continues to be found. It is also important for those of us in practice to remember that not every opportunity to do more for patients translates into benefit for them, and the adverse effects of screening need to be considered when advocating for invasive screening. T. R. Levin University of California, San Francisco San Francisco, California
Vol. 97, No. 1, 2002 ISSN 0002-9270/02/$22.00
WORLD LITERATURE REVIEW Editor: David Johnson, M.D., F.A.C.G. REVIEW PANEL Luis Balart Jamie Barkin David Bjorkman Cedric Bremner Randall Burt Harold Conn Jack DiPalma Hashem El-Serag M. Brian Fennerty
Mark Flemmer Christopher Gostout Robert Hawes Jorge Herrera Brenda Hoffman Kelvin Hornbuckle Doug Howerton Sunanda Kane
Could Screening for Colorectal Cancer Be Harmful? Hoff G, Thiis-Evensen E, Grotmol T, et al. Do Undesirable Effects of Screening Affect All-cause Mortality in Flexible Sigmoidoscopy Programmes? Experience From the Telemark Polyp Study 1983–1996 Eur J Cancer Prev 2001;10:131–7
ABSTRACT There is substantial evidence for the beneficial effect of screening programs aimed at reducing mortality from colorectal cancer. The effect on all-cause mortality, however, may not necessarily be beneficial. In this small randomized trial (n ⫽ 799), colorectal cancer incidence was reduced 80% among subjects undergoing screening flexible sigmoidoscopy with colonoscopy follow-up and surveillance over 13 yr for subjects with polyps at initial screening. The all-cause mortality was higher, however, among subjects in the screened group, mainly because of an excess of cardiovascular deaths. This study evaluated the long term effects of informing participants about findings at flexible sigmoidoscopy screening. There were no severe complications, and there was no long term difference in deaths related to whether there had been any mucosal rupture (biopsy or snare resection). As a group, those who were informed that they had polyps tended to improve their smoking habits more than those informed that they had no polyps. The group with polyps had a trend toward a smaller increase in body mass index (⫹0.7 [95% CI ⫽ 0.2–1.1]) than the polyp-free group (⫹1.2 [95% CI ⫽ 0.9 –1.6]) (p ⫽ 0.07). The authors suggest that flexible sigmoidoscopy screening may be associated with unfavorable lifestyle changes among screenees without polyps, an effect that may more than outweigh the beneficial effect of screening. (Am J Gastroenterol 2002;97:198. © 2002 by Am. Coll. of Gastroenterology)
COMMENT Ample evidence supports screening for colorectal cancer in terms of decreased colorectal cancer incidence and mortal-
Philip Katz Timothy Koch Mark Lawson Theodore Levin Edward C. Oldfield III David Ott C. S. Pitchumoni K. Rajender Reddy
Douglas Rex Arvey Rogers Richard Sampliner Paul Souney Christina Surawicz Nimish Vakil Harlan Vingan Maurits Wiersema
ity. The principal trade-offs between tests have been the increased sensitivity of more invasive tests (colonoscopy) compared with the decreased risk of immediate complications with less invasive tests (such as fecal occult blood test and flexible sigmoidoscopy). There is one concern that should give at least some pause to those of us who advocate for colorectal cancer screening: the lack of evidence for a decrease in all-cause mortality in people who are screened. There are at least two possible explanations for this observation. First, colorectal cancer accounts for a relatively small proportion of the overall mortality among screening-aged people, with cardiovascular death accounting for the lion’s share. If colorectal cancer screening has no effect on cardiovascular death, then any decrease in colorectal cancer mortality is overshadowed by the substantial impact of cardiovascular disease on overall mortality. This small study raises the potential of another, more ominous explanation—namely, that colorectal cancer screening may actually cause an increase in cardiovascular death outweighing any benefits of screening. The principle limitation of this study is the lack of data collection among controls; therefore, any conclusions drawn should at best be considered “preliminary.” In addition, the differences found in the screened group between those with polyps found and those without polyps were not significant for smoking (p ⫽ 0.10) or for body mass index (p ⫽ 0.06), when both improving and worsening were combined. The important comparison, for which these risk factors are surrogates, is mortality, and there were no mortality differences between those with polyps and those without. Despite these limitations, it will be important for future studies of colorectal cancer screening to attempt to explain the relationship between screening and cardiovascular mortality, if such an association continues to be found. It is also important for those of us in practice to remember that not every opportunity to do more for patients translates into benefit for them, and the adverse effects of screening need to be considered when advocating for invasive screening. T. R. Levin University of California, San Francisco San Francisco, California