Low-dose aspirin use after diagnosis of colorectal cancer does not increase survival: a case-control analysis of a population-based cohort.
OBJECTIVE
Individuals who began taking low-dose aspirin before they were diagnosed with colorectal cancer were reported to have longer survival times than patients who did not take this drug. We investigated survival times of patients who begin taking low-dose aspirin after a diagnosis of colorectal cancer in a large population-based cohort study.


METHODS
We performed a nested case-control analysis using a cohort of 4794 patients diagnosed with colorectal cancer from 1998 through 2007, identified from the UK Clinical Practice Research Datalink and confirmed by cancer registries. There were 1559 colorectal cancer-specific deaths, recorded by the Office of National Statistics; these were each matched with up to 5 risk-set controls. Conditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI), based on practitioner-recorded aspirin usage.


RESULTS
Overall, low-dose aspirin use after a diagnosis of colorectal cancer was not associated with colorectal cancer-specific mortality (adjusted OR = 1.06; 95% CI: 0.92-1.24) or all-cause mortality (adjusted OR = 1.06; 95% CI: 0.94-1.19). A dose-response association was not apparent; for example, low-dose aspirin use for more than 1 year after diagnosis was not associated with colorectal cancer-specific mortality (adjusted OR = 0.98; 95% CI: 0.82-1.19). There was also no association between low-dose aspirin usage and colon cancer-specific mortality (adjusted OR = 1.02; 95% CI: 0.83-1.25) or rectal cancer-specific mortality (adjusted OR = 1.10; 95% CI: 0.88-1.38).


CONCLUSIONS
In a large population-based cohort, low-dose aspirin usage after diagnosis of colorectal cancer did not increase survival time.
Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland. Electronic address: c.cardwell@qub.ac.uk.
Chris R
CR
Cardwell
Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland; Centre of Excellence for Public Health (NI), Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
Andrew T
AT
Kunzmann
Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland; Centre of Excellence for Public Health (NI), Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
Marie M
MM
Cantwell
School of Pharmacy, Queen's University Belfast, Northern Ireland.
Carmel
C
Hughes
Department of Medicine, University of North Carolina School of Medicine Chapel Hill, North Carolina.
John A
JA
Baron
Department of Cellular Pathology, Queen's Medical Centre, Nottingham University Hospitals, NHS Trust, UK; The John van Geest Cancer Research Centre, Nottingham Trent University, Nottingham, UK.
Des G
DG
Powe
Cancer Epidemiology and Health Services Research Group, Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland; Centre of Excellence for Public Health (NI), Centre for Public Health, Queen's University Belfast, Belfast, Northern Ireland.
Liam J
LJ
Murray
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use*; D016022:Case-Control Studies; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012307:Risk Factors; D015996:Survival Rate
D000894:Anti-Inflammatory Agents, Non-Steroidal; D001241:Aspirin
Antiplatelet Drugs; CPRD; Colorectal Neoplasms; Pharmacoepidemiology