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Forgoing chemo linked to worse survival in older patients with advanced colon cancer who had dementia

 

Bottom Line: A pre-existing diagnosis of dementia was associated with increased risk of death for older patients with advanced colon cancer; however, some of the effects of dementia on survival could be mediated by receipt of chemotherapy.

Journal in Which the Study was Published: Cancer Epidemiology, Biomarkers Prevention, a journal of the American Association for Cancer Research.

Author: Yingjia Chen, PhD, a postdoctoral fellow in the Memory and Aging Center in the Department of Neurology at University of California, San Francisco.

How the Study Was Conducted and Results: Chen and colleagues started by performing a retrospective cohort study using SEER-Medicare data for 3,903 adults over the age of 65 with confirmed diagnoses of stage 3 colon cancer and dementia. Of them, 60.9 percent were women, and 79.7 percent were white. A pre-existing dementia diagnosis was confirmed by a formal entry in medical records or prescription records for one of four FDA-approved drugs for temporarily improving dementia symptoms: donepezil, galantamine, memantine, and rivastigmine. The researchers found that a pre-existing diagnosis of dementia was associated with increased risk of death by 45 percent and the average mean survival time for patients with stage 3 colon cancer and pre-existing dementia was only 57 percent that of their cognitively healthy counterparts.

Next, Chen and colleagues examined the impact of the receipt of chemotherapy on survival outcome in patients with dementia. “We assessed the mediating effect of chemotherapy using a statistical method called accelerated failure time model in the context of the counterfactual framework and found that the receipt of chemotherapy was significantly associated with survival,” explained Chen. “This type of analysis allowed us to determine that not receiving chemotherapy accounted for 13 percent of the poorer survival outcomes for patients with pre-existing dementia.

Author Comment: “Both colon cancer and dementia are prevalent among the growing elderly population and have a high risk of co-occurrence,” said Chen. “Chemotherapy may be challenging for older adults with dementia, but our research shows that some may still benefit.”

“In general, dementia patients with advanced colon cancer are being undertreated. There are many good reasons why physicians, patients, and families may decide to forgo chemotherapy, including toxicity, functional limitations of the patient, or if patients are diagnosed with colon cancer at later stages,” Chen explained. “However, our findings suggest that chemotherapy may increase survival and should be considered for advanced colon cancer patients with dementia in a similar fashion as for those without dementia.”

Limitations: Limitations of the study include that detailed information about dementia diagnoses or functional status were not available, so the researchers were not able to identify the extent of dementia. The investigators were also unable to know the reasons why chemotherapy was or was not chosen, nor the regimens administered.

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Funding Disclosures: The study was supported by the Biostatistics Shared Resource of the UC Davis Comprehensive Cancer Center, which is funded by a grant awarded by the National Cancer Institute. Chen declares no conflicts of interest.

To interview Yingjia Chen, contact Julia Gunther at julia.gunther@aacr.org or 215-446-6896.

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About the American Association for Cancer Research

Founded in 1907, the American Association for Cancer Research (AACR) is the world’s first and largest professional organization dedicated to advancing cancer research and its mission to prevent and cure cancer. AACR membership includes more than 37,000 laboratory, translational, and clinical researchers; population scientists; other health care professionals; and patient advocates residing in 108 countries. The AACR marshals the full spectrum of expertise of the cancer community to accelerate progress in the prevention, biology, diagnosis, and treatment of cancer by annually convening more than 30 conferences and educational workshops, the largest of which is the AACR Annual Meeting with more than 21,900 attendees. In addition, the AACR publishes eight prestigious, peer-reviewed scientific journals and a magazine for cancer survivors, patients, and their caregivers. The AACR funds meritorious research directly as well as in cooperation with numerous cancer organizations. As the Scientific Partner of Stand Up To Cancer, the AACR provides expert peer review, grants administration, and scientific oversight of team science and individual investigator grants in cancer research that have the potential for near-term patient benefit. The AACR actively communicates with legislators and other policymakers about the value of cancer research and related biomedical science in saving lives from cancer. For more information about the AACR, visit http://www.AACR.org.

 

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