Colorectal cancer: Difference between revisions

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imported>Robert Badgett
imported>Robert Badgett
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{{subpages}}
==Pathophysiology==
Colorectal cancer probably arises from colorectal polyps.<ref name="pmid17167138">{{cite journal |author=Levine JS, Ahnen DJ |title=Clinical practice. Adenomatous polyps of the colon |journal=N. Engl. J. Med. |volume=355 |issue=24 |pages=2551–7 |year=2006 |month=December |pmid=17167138 |doi=10.1056/NEJMcp063038 |url=http://content.nejm.org/cgi/content/full/355/24/2551 |issn=}}</ref> Adenomatous polyps convert to cancers at a rate of about 1% per year.<ref name="pmid3653628">{{cite journal |author=Stryker SJ, Wolff BG, Culp CE, Libbe SD, Ilstrup DM, MacCarty RL |title=Natural history of untreated colonic polyps |journal=Gastroenterology |volume=93 |issue=5 |pages=1009–13 |year=1987 |month=November |pmid=3653628 |doi= |url= |issn=}}</ref>
==Treatment==
{{PDQ-treatment|http://www.cancer.gov/cancertopics/pdq/treatment/colon/HealthProfessional/page5}}
===Medications===
;Cetuximab
Cetuximab, an I<sub>g</sub>G1 chimeric monoclonal antibody against epidermal growth factor receptor, may help according to a [[randomized controlled trial]].<ref name="pmid18003960">{{cite journal |author=Jonker DJ, O'Callaghan CJ, Karapetis CS, ''et al'' |title=Cetuximab for the treatment of colorectal cancer |journal=N. Engl. J. Med. |volume=357 |issue=20 |pages=2040–8 |year=2007 |pmid=18003960 |doi=10.1056/NEJMoa071834}}</ref>
==Prognosis==
{{Image|5-Year Relative Survival Rates By Year Dx By Cancer Site All Ages, All Races, Both Sexes 1975-2000.jpg|right|350px|5-Year Relative Survival Rates By Year Dx By Cancer Site All Ages, All Races, Both Sexes 1975-2000.}}
===Staging information===
{{PDQ-staging|http://www.cancer.gov/cancertopics/pdq/treatment/colon/HealthProfessional/page4}}
==Screening==
{{main|colonic polyp}}
===Practice guidelines===
A [[clinical practice guideline]] by the [[US Preventive Services Task Force]] has addressed colorectal cancer:<ref name="pmid18838716">{{cite journal |author= |title=Screening for Colorectal Cancer: U.S. Preventive Services Task Force Recommendation Statement |journal=Annals of Internal Medicine |volume= |issue= |pages= |year=2008 |month=October |pmid=18838716 |doi= |url=http://www.annals.org/cgi/content/full/0000605-200811040-00243v1 |issn=}}</ref>
* "recommends screening for colorectal cancer using fecal  occult blood testing, sigmoidoscopy, or colonoscopy in adults,  beginning at age 50 years and continuing until age 75 years."
* "recommends against routine screening for colorectal  cancer in adults 76 to 85 years of age. There may be considerations  that support colorectal cancer screening in an individual patient."
* "recommends against screening for colorectal cancer in  adults older than age 85 years"
* "the evidence is insufficient to assess the benefits and harms of computed tomographic colonography and fecal DNA testing (a subsequent study found that DNA was more [[sensitivity and specificity|sensitive]] but less [[sensitivity and specificity|specific]]<ref name="pmid18838724">{{cite journal |author=Ahlquist DA, Sargent DJ, Loprinzi CL, ''et al'' |title=Stool DNA and occult blood testing for screen detection of colorectal neoplasia |journal=Ann. Intern. Med. |volume=149 |issue=7 |pages=441–50, W81 |year=2008 |month=October |pmid=18838724 |doi= |url=http://www.annals.org/cgi/pmidlookup?view=long&pmid=18838724 |issn=}}</ref>)"
A [[clinical practice guideline]] jointly written by the [[American Cancer Society]] and other groups recommends one of:<ref>Levin, B., Lieberman, D. A., McFarland, B., Smith, R. A., Brooks, D., Andrews, K. S., et al. (2008). [http://caonline.amcancersoc.org/cgi/content/full/CA.2007.0018v1 Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-society Task Force on Colorectal Cancer, and the American College of Radiology]. CA Cancer J Clin, CA.2007.0018. {{doi|10.3322/CA.2007.0018}}.</ref>
* Flexible sigmoidoscopy every 5 years
* Barium enema every 5 years
* Virtual colonography (a noninvasive test based on [[computed tomography]]) every 5 years
* Colonoscopy every 10 years
When polyps are found, a [[clinical practice guideline]] jointly written by the [[American Cancer Society]] and other groups states:<ref name="pmid16697750">{{cite journal |author=Winawer SJ, Zauber AG, Fletcher RH, ''et al'' |title=Guidelines for colonoscopy surveillance after polypectomy: a consensus update by the US Multi-Society Task Force on Colorectal Cancer and the American Cancer Society |journal=Gastroenterology |volume=130 |issue=6 |pages=1872–85 |year=2006 |month=May |pmid=16697750 |doi=10.1053/j.gastro.2006.03.012 |url=http://www.gastrojournal.org/article/S0016-5085(06)00561-0/fulltext |issn=}}</ref>
* High risk polyps are 1) 3 or more synchronous adenomas, 2) adenomas ≥1 cm in diameter, or 3) villous histology or high-grade dysplasia.
* High risk polyps should have follow-up colonoscopy in 3 years
* Low risk polyps should have repeat colonoscopy  in 5 to 10 years
* If no adenomas are found, follow-up evaluation should be at 10 years
A validation of these guidelines found:<ref name="pmid18347350">{{cite journal |author=Laiyemo AO, Murphy G, Albert PS, ''et al'' |title=Postpolypectomy colonoscopy surveillance guidelines: predictive accuracy for advanced adenoma at 4 years |journal=Ann. Intern. Med. |volume=148 |issue=6 |pages=419–26 |year=2008 |month=March |pmid=18347350 |doi= |url=http://www.annals.org/cgi/content/full/148/6/419 |issn=}}</ref>
* High risk adenomas - 9% of an advanced adenoma at 4 years of follow-up.
* Low risk adenomas - 5% of an advanced adenoma at 4 years of follow-up.
===Evidence===
===Evidence===
{| class="wikitable"
{| class="wikitable"
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|  Ontario Cancer Registry<ref name="pmid19075198"/><br/>[[Case-control study]]<br/>10,292 case patients and 51,460 controls for 7.8 years || Colorectal cancer death:<br/>[[Odds ratio]] 0.69 || align="center"|325
|  Ontario Cancer Registry<ref name="pmid19075198"/><br/>[[Case-control study]]<br/>10,292 case patients and 51,460 controls for 7.8 years || Colorectal cancer death:<br/>[[Odds ratio]] 0.69 || align="center"|325
|}
|}
==Prevention==
===Aspirin chemoprophylaxis===
A [[clinical practice guideline]] by the [http://www.ahrq.gov/clinic/uspstfix.htm U.S. Preventive Services Task Force (USPSTF)] recommended against taking [[aspirin]] ([http://www.ahrq.gov/clinic/3rduspstf/ratings.htm grade D recommendation]).<ref name="pmid17339621">{{cite journal |author= |title=Routine aspirin or nonsteroidal anti-inflammatory drugs for the primary prevention of colorectal cancer: U.S. Preventive Services Task Force recommendation statement |journal=Ann. Intern. Med. |volume=146 |issue=5 |pages=361-4 |year=2007 |id=pmid=17339621 |doi=}} PMID 17339621</ref> The Task Force acknowledged that aspirin may reduce the incidence of colorectal cancer, but "concluded that harms outweigh the benefits of aspirin and NSAID use for the prevention of colorectal cancer". A subsequent [[meta-analysis]] concluded "300 mg or more of aspirin a day for about 5 years is effective in primary prevention of colorectal cancer in randomised controlled trials, with a latency of about 10 years".<ref name="pmid17499602">{{cite journal |author=Flossmann E, Rothwell PM |title=Effect of aspirin on long-term risk of colorectal cancer: consistent evidence from randomised and observational studies |journal=Lancet |volume=369 |issue=9573 |pages=1603-13 |year=2007 |pmid=17499602 |doi=10.1016/S0140-6736(07)60747-8}} PMID 17499602</ref> However, long-term doses over 81 mg per day may increase bleeding events.<ref name="pmid17488967">{{cite journal |author=Campbell CL, Smyth S, Montalescot G, Steinhubl SR |title=Aspirin dose for the prevention of cardiovascular disease: a systematic review |journal=JAMA |volume=297 |issue=18 |pages=2018-24 |year=2007 |pmid=17488967 |doi=10.1001/jama.297.18.2018}} PMID 17488967</ref>
===Calcium===
A [[meta-analysis]] by the [[Cochrane Collaboration]] of [[randomized controlled trial]]s published through 2002  concluded "Although the evidence from two RCTs suggests that calcium supplementation might contribute to a moderate degree to the prevention of colorectal adenomatous polyps, this does not constitute sufficient evidence to recommend the general use of calcium supplements to prevent colorectal cancer.".<ref name="pmid16034903">{{cite journal |author=Weingarten MA, Zalmanovici A, Yaphe J |title=Dietary calcium supplementation for preventing colorectal cancer and adenomatous polyps |journal=Cochrane database of systematic reviews (Online) |volume= |issue=3 |pages=CD003548 |year=2005 |pmid=16034903 |doi=10.1002/14651858.CD003548.pub3}}</ref> Subsequently, one [[randomized controlled trial]] by the [[Women's Health Initiative]] (WHI) reported negative results.<ref name="pmid16481636">{{cite journal |author=Wactawski-Wende J, Kotchen JM, Anderson GL, ''et al'' |title=Calcium plus vitamin D supplementation and the risk of colorectal cancer |journal=N. Engl. J. Med. |volume=354 |issue=7 |pages=684-96 |year=2006 |pmid=16481636 |doi=10.1056/NEJMoa055222}}</ref> A second [[randomized controlled trial]] reported reduction in all cancers, but had insufficient colorectal cancers for analysis.<ref name="pmid17556697">{{cite journal |author=Lappe JM, Travers-Gustafson D, Davies KM, Recker RR, Heaney RP |title=Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial |journal=Am. J. Clin. Nutr. |volume=85 |issue=6 |pages=1586-91 |year=2007 |pmid=17556697 |doi=|url=http://www.ajcn.org/cgi/content/full/85/6/1586}}</ref>
==References==
<references/>

Revision as of 19:47, 4 March 2009

Evidence

Selected studies of the benefit from colorectal cancer screening[1][2][3][4][5][6]
Procedure Study Benefit Number needed to screen
(assuming control rate of 1%)
Fecal occult blood annually Minnesota Colon Cancer Control Study[1]
Randomized controlled trial
46,551 patients for 13 years		 Colorectal cancer death:
Relative risk ratio 0.67
Relative risk reduction 33%		 305
Sigmoidoscopy Kaiser Permanente[3]
Case-control study
261 case patients and 868 control patients for 10 years		 Colorectal cancer death:
Odds ratio 0.41		 170
Telemark Polyp Study I[4]
Cohort study
400 case patients and 399 controls for 7 to 11 years		 Colorectal cancer incidence:
Relative risk ratio 0.2
Relative risk reduction 80%		 125
Colonoscopy National Polyp Study[5]
Cohort study
1418 patients for 5.8 years		 Colorectal cancer incidence:
Relative risk ratio 0.1
Relative risk reduction 90%		 111
Ontario Cancer Registry[6]
Case-control study
10,292 case patients and 51,460 controls for 7.8 years		 Colorectal cancer death:
Odds ratio 0.69		 325
  1. ↑ 1.0 1.1 Mandel JS, Bond JH, Church TR, et al (May 1993). "Reducing mortality from colorectal cancer by screening for fecal occult blood. Minnesota Colon Cancer Control Study". N. Engl. J. Med. 328 (19): 1365–71. PMID 8474513. [e]
  2. ↑ Ransohoff DF, Lang CA (March 1993). "Sigmoidoscopic screening in the 1990s". JAMA 269 (10): 1278–81. PMID 8437306. [e]
  3. ↑ 3.0 3.1 Selby JV, Friedman GD, Quesenberry CP, Weiss NS (March 1992). "A case-control study of screening sigmoidoscopy and mortality from colorectal cancer". N. Engl. J. Med. 326 (10): 653–7. PMID 1736103. [e]
  4. ↑ 4.0 4.1 Thiis-Evensen E, Hoff GS, Sauar J, Langmark F, Majak BM, Vatn MH (April 1999). "Population-based surveillance by colonoscopy: effect on the incidence of colorectal cancer. Telemark Polyp Study I". Scand. J. Gastroenterol. 34 (4): 414–20. PMID 10365903. [e]
  5. ↑ 5.0 5.1 Winawer SJ, Zauber AG, Ho MN, et al (December 1993). "Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup". N. Engl. J. Med. 329 (27): 1977–81. PMID 8247072. [e]
  6. ↑ 6.0 6.1 Baxter NN, Goldwasser MA, Paszat LF, Saskin R, Urbach DR, Rabeneck L (January 2009). "Association of colonoscopy and death from colorectal cancer". Ann. Intern. Med. 150 (1): 1–8. PMID 19075198. [e]
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