November 07, 2012Volume 7 - Issue 45 

DynaMed Weekly Update

For the week ending November 2, 2012

Last week 486 articles were evaluated via DynaMed's Systematic Literature Surveillance and 248 were added to DynaMed content.   


Based on the editors' criteria of selecting "articles most likely to change clinical practice," one article of significant interest was selected for the DynaMed Weekly Update.

Feature Article

Regular Aspirin Use After Diagnosis of Colorectal Cancer May Reduce Mortality in Patients with Tumor PIK3CA Mutation


A number of randomized trials and observational studies have investigated the efficacy of regular aspirin use for colorectal cancer prevention. Though results have been mixed, the benefits that have been shown are thought to result from aspirin's inhibition of cyclooxygenase-2 (COX-2). COX-2 (also known as prostaglandin-endoperoxide synthase 2 [PTGS2]) promotes cell proliferation and inflammation and is overexpressed in many colorectal cancers.


There has been less research on the effects of regular aspirin use after the diagnosis of colorectal cancer. In one cohort study with 1,279 participants from the Nurses' Health study and Health Professionals Follow-up Study, aspirin use was associated with an overall survival advantage during 12 years of follow-up in patients taking aspirin (JAMA 2009 Aug 12;302(6):649). In a subgroup analyses, this advantage was found in patients with primary tumors that overexpressed COX-2, but not in cases of weak or absent COX-2 expression. A new analysis in the same population now suggests that aspirin may be of most benefit in patients whose cancers have a mutation in the PIK3CA gene, which may upregulate COX-2 activity and inhibit apoptosis in cancer cells.  


A total of 964 patients (mean age 68 years, 56% female) with colorectal cancer with known PIK3CA status were followed for median 12.75 years. The PIK3CA mutation was present in 16.7%, while the remainder of patients had wild-type PIK3CA cancers. After cancer diagnosis, 41% with the mutation and 42% without the mutation used aspirin regularly (defined as use during most weeks, regardless of dose or indication).


Comparing regular aspirin use vs. nonuse in patients with the PIK3CA mutation, overall mortality was 27.3% vs. 46.3% (p < 0.05, NNT 6), and cancer-specific mortality was 4.5% vs. 27.4% (p < 0.05, NNT 5) (level 2 [mid-level] evidence). In patients without the mutation, there were no significant differences in overall mortality (40.7% vs. 42.1%) or cancer-specific mortality (19.3% vs. 20.6%). About 43% overall used aspirin regularly prior to diagnosis, but there were no significant associations found between prior use and mortality (N Engl J Med 2012 Oct 25;367(17):1596).


For more information, see the Treatment of nonmetastatic colon cancer and Treatment of nonmetastatic rectal cancer topics in DynaMed.  

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New Topics Added to DynaMed this Week 

Angle-closure glaucoma

Call for Peer Reviewers

We are currently seeking reviewers for:  

Esophageal cancer

Familial adenomatous polyposis

Gastrointestinal stromal tumor


Learn more about the DynaMed Contribution Opportunities:

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About DynaMed Weekly Update

Prepared by the clinician members of the DynaMed Editorial Team, DynaMed Weekly Update is a compilation of one to five articles selected from DynaMed's Systematic Literature Surveillance as articles most likely to change clinical practice.

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CME Information


0.25 AMA PRA Category I Credit(s)™
Family Physicians: 0.25 Prescribed credits
Nurse Practitioners: 0.25 Contact hours
Release Date: November 07, 2012
Expiration Date: November 07, 2013
Estimated Completion Time:
15 minutes
There is no fee for this activity.

To Receive Credit 
In order to receive your certificate of participation, you should read the information about this activity, including the disclosure statements, review the entire activity, take the post-test, and complete the evaluation form. You may then follow the directions to print your certificate of participation. To begin, click the CME icon at the end of the article.

Program Overview

Learning Objectives


Upon successful completion of this educational program, the reader should be able to:


1. Discuss the significance of this article as it relates to your clinical practice.
2. Be able to apply this knowledge to your patient's diagnosis, treatment and management.


Faculty Information
Alan Ehrlich, MD - Assistant Clinical Professor in Family Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA; Senior Deputy Editor, DynaMed, Ipswich, Massachusetts, USA

Michael Fleming, MD, FAAFP - Assistant Clinical Professor of Family Medicine and Comprehensive Care, LSU Health Science Center School of Medicine, Shreveport, Louisiana, USA; Assistant Clinical Professor of Family Medicine, Department of Family and Community Medicine, Tulane University Medical School, New Orleans, Louisiana, USA; Chief Medical Officer, Amedisys, Inc. & Antidote Education Company

Dr. Ehrlich, Dr. Fleming, DynaMed Editorial Team members, and the staff of Antidote Education Company have disclosed that they have no relevant financial relationships or conflicts of interest with commercial interests related directly or indirectly to this educational activity.


No commercial support has been received for this activity.

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ACCME: This activity has been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education through the joint sponsorship of Antidote Education Company and EBSCO Publishing. Antidote is accredited by the ACCME to provide continuing medical education for physicians. Antidote Education Company designates this enduring activity for a maximum of 0.25 AMA PRA Category 1 Credits™. Physicians should only claim credit commensurate with the extent of their participation in the activity.

AAFP: Enduring Material activity, DynaMed Weekly Update, has been reviewed and is acceptable for up to 13 Prescribed credits by the American Academy of Family Physicians. AAFP certification begins March 7, 2012. Term of approval is for one year from this date with the option of yearly renewal. Each Weekly Update is worth .25 Prescribed credits. Physicians should claim only the credit commensurate with the extent of their participation in the activity.


AANP: This program is approved for 0.25 contact hour of continuing education by the American Academy of Nurse Practitioners.


Program ID: 1210392J

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