Incident cancer risk after the start of aspirin use: results from a Dutch population-based cohort study of low dose aspirin users

Potential beneficial effects of long-term aspirin use on the prevalence of colorectal cancer: a population-based study of the US Nationwide Inpatient Sample

PURPOSE

Whether long-term aspirin usage is associated with colorectal cancer (CRC) risk needs more evidence. The study evaluated the association between long-term aspirin use and prevalence of CRC in a large, nationally representative database.

METHODS

Hospitalized patients aged ≥ 50 years during 2018 were identified in the United States (US) National Inpatient Sample (NIS). Patients without complete information of age, sex, race, income, and insurance status were excluded, as well as those with inflammatory bowel disease (IBD) or malignancies other than CRC. Propensity score matching (PSM) was applied to balance the characteristics between patients with and without long-term aspirin use. Logistic regressions were performed to determine the relationship between long-term aspirin use and the presence of CRC. CRC and aspirin use were identified through the administrative International Classification of Diseases (ICD) codes.

RESULTS

Data from 3,490,226 patients were included, in which 688,018 (19.7%) had a record of long-term aspirin use. After 1:1 PSM, there remained 1,376,006 patients, representing 6,880,029 individuals in the US after weighting. After adjusting for confounders, long-term aspirin use was significantly associated with lower CRC odds (adjusted odds ratio [aOR] = 0.64, 95% confidence interval [CI] 0.62, 0.67). This association was not changed when stratified by age, sex, race, body mass index (BMI), and smoking.

CONCLUSIONS

From a national inpatient dataset, US adults ≥ 50 years on long-term aspirin are less likely to have CRC, regardless of age, sex, race, BMI, and smoking status.

Prophylactic aspirin intake and breast cancer risk; A systematic review and meta-analysis of observational cohort studies

Breast Cancer (BC) is the most common cancer amongst women. The chemo-preventative effects of aspirin on breast cancer have been demonstrated in several longitudinal studies however previous meta-analysis have shown inconsistent results. This study aimed to assess the relationship between aspirin use and BC risk, and to determine if there is a dose-response relationship between aspirin and BC risk. Studies incorporating BC risk with aspirin use published within the last twenty years were included. The study report is based on the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) and Meta-Analysis of Observational Studies in Epidemiology. Twenty-eight cohort studies that reported BC incidence during a follow up of 4.4-32 years were included. Compared to non-users, aspirin users had a reduced risk of BC (HR = 0.91, c.i 0.81-0.97, p = 0.002). There was no obvious association between BC risk reduction and aspirin dose (HR = 0.94, c.i 0.85-1.04) or duration (HR = 0.86, c.i 0.71-1.03). Frequency, however, was associated with a reduced risk of BC (HR = 0.90, c.i 0.82-0.98). A risk reduction was observed in oestrogen receptor (ER) positive tumours (HR = 0.90, c.i 0.86-0.96, p = 0.0004) while no relationship was observed with ER negative tumours (HR = 0.94, c.i 0.85-1.05). This meta-analysis found an association between aspirin intake and BC risk reduction. A more favourable outcome was noted with ingestion of greater than 6 tablets of aspirin per week. Aspirin had a significant risk reduction in patients with ER positive tumours compared to ER negative BC.

Knowledge and belief of fecal occult blood screening: A systematic review

INTRODUCTION

Colorectal cancer (CRC) is associated with a high incidence and mortality rate. Fecal occult blood test (FOBT) is effective in the prevention of CRC.

OBJECTIVE

This study aimed to assess knowledge and beliefs regarding FOBT-based screening.

METHODS

This study used PubMed, Cochrane Library, MEDLINE Complete, and Web of Science to search for articles. Original full-text studies in English language focusing on knowledge and beliefs of FOBT screening were included.

RESULTS

A total of 32 articles were included. This study indicated that the population in most studies had inadequate knowledge and lacked beliefs toward FOBT-based screening. Most of the extracted studies showed that less than half of the participants had heard of FOBT-based screening. Six studies showed that less than 50% of participants had knowledge of FOBT age. Three studies found that less than 40% of participants were aware of the screening interval. Some participants perceived the benefits of FOBT-based screening, while others perceived many barriers to the test.

CONCLUSION

Participants' knowledge and belief in FOBT-based screening were insufficient. This review highlights the importance of educational programs to increase knowledge and beliefs regarding FOBT-based screening. It is important to include FOBT-based screening in the health care system to promote the secondary prevention of CRC.

Antiplatelet drugs and breast cancer risk in a large nationwide Danish case-control study

Low-dose aspirin has been hypothesized to prevent cancer risk by inhibiting platelet aggregation. However, the anti-cancer effect of low-dose aspirin has recently been questioned and its effect on breast cancer development remains unclear. The impact of other antiplatelet drugs on breast cancer risk has rarely been evaluated. Thus, this study aimed to investigate the associations between breast cancer risk and antiplatelet drug use in a nationwide nested case-control study. From the Danish healthcare registries, we identified as cases all women with invasive breast cancer diagnosis between 2001 and 2018 (n = 68 852). The date of diagnosis corresponded to the index date. We matched cases to 10 population controls on age and calendar time, using risk set sampling. Controls were assigned the same index date as their matched case. We used the prescription registry to identify exposure to low-dose aspirin, clopidogrel and dipyridamole. We defined ever use of antiplatelet drugs as at least two prescriptions filled up to 1 year before the index date. We applied conditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals for breast cancer associated with the use of antiplatelet drugs, overall, by breast cancer subtype and by cumulative dose. Twelve percent of women had ever been exposed to low-dose aspirin, 2% to clopidogrel and 2% to dipyridamole. In multivariable models, breast cancer risk was not associated with ever use of low-dose aspirin (OR = 1.00 [0.97-1.03]), clopidogrel (OR = 0.93 [0.87-1.00]), and dipyridamole (OR = 1.02 [0.94-1.10]), compared with never use, and there was no evidence of a dose-response relation. However, we found an inverse association between dipyridamole use and breast cancer risk among women aged <55 years old, with suggestion of a dose-response relationship (OR per 1000 Defined Daily Doses = 0.72 [0.54-0.95]). Associations did not differ by breast cancer histological type, estrogen receptor status or clinical stage at diagnosis. Overall, the findings from this study do not support the use of antiplatelet drugs for breast cancer prevention.

Analgesic Use and Circulating Estrogens, Androgens, and Their Metabolites in the Women's Health Initiative Observational Study

Though studies have observed inverse associations between use of analgesics (aspirin, NSAIDs, and acetaminophen) and the risk of several cancers, the potential biological mechanisms underlying these associations are unclear. We investigated the relationship between analgesic use and serum concentrations of estrogens, androgens, and their metabolites among postmenopausal women to provide insights on whether analgesic use might influence endogenous hormone levels, which could in turn influence hormone-related cancer risk. The study included 1,860 postmenopausal women from two case-control studies nested within the Women's Health Initiative Observational Study. Analgesic use was reported at study baseline. Fifteen estrogens and estrogen metabolites and 12 androgens and androgen metabolites were quantified in baseline serum by LC/MS-MS. Linear regression with inverse probability weighting, stratified by menopausal hormone therapy (MHT) use, was used to estimate adjusted geometric mean concentrations of each hormone by analgesic use. Among women not currently using MHT (n = 951), low-dose aspirin (<100 mg) use was associated with a higher serum concentration of estrone, estradiol, and 2, 4, and 16 hydroxylated metabolites. Use of regular-dose aspirin (≥100 mg), non-aspirin NSAIDs, and acetaminophen was not associated with serum concentrations of estrogens, androgens, or their metabolites. This study highlights the importance of examining aspirin use by dose and suggests that low-dose aspirin may influence endogenous estrogen concentrations.

PREVENTION RELEVANCE

This study explores a potential pathway by which analgesic medications such as aspirin may prevent hormone-related cancers. The findings support a positive association between low-dose aspirin use and endogenous estrogens, indicating that further elucidation of the interplay between low-dose aspirin, estrogen concentrations, and cancer risk is needed.

Safety and effectiveness of low-dose aspirin for the prevention of gastrointestinal cancer in adults without atherosclerotic cardiovascular disease: a population-based cohort study

OBJECTIVE

To assess the association between low-dose aspirin and the incidence of colorectal cancer (CRC), gastric cancer (GC), oesophageal cancer (EC) and gastrointestinal bleeding (GIB) in adults without established atherosclerotic cardiovascular disease.

DESIGN

Cohort study with propensity score matching of new-users of aspirin to non-users.

SETTING

Clinical Data Analysis and Reporting System database, Hong Kong.

PARTICIPANTS

Adults ≥40 years with a prescription start date of either low-dose aspirin (75-300 mg/daily) or paracetamol (non-aspirin users) between 1 January 2004 to 31 December 2008 without a history of atherosclerotic cardiovascular disease.

MAIN OUTCOME MEASURES

The primary outcome was the first diagnosis of gastrointestinal cancer (either CRC, GC or EC) and the secondary outcome was GIB. Individuals were followed from index date of prescription until the earliest occurrence of an outcome of interest, an incident diagnosis of any type of cancer besides the outcome, death or until 31 December 2017. A competing risk survival analysis was used to estimate HRs and 95% CIs with death as the competing risk.

RESULTS

After matching, 49 679 aspirin and non-aspirin users were included. The median (IQR) follow-up was 10.0 (6.4) years. HRs for low-dose aspirin compared with non-aspirin users were 0.83 for CRC (95% CI, 0.76 to 0.91), 0.77 for GC (95% CI, 0.65 to 0.92) and 0.88 for EC (95% CI, 0.67 to 1.16). Patients prescribed low-dose aspirin had an increased risk of GIB (HR 1.15, 95% CI, 1.11 to 1.20), except for patients prescribed proton pump inhibitors or histamine H2-receptor antagonists (HR 1.03, 95% CI, 0.96 to 1.10).

CONCLUSION

In this cohort study of Chinese adults, patients prescribed low-dose aspirin had reduced risks of CRC and GC and an increased risk of GIB. Among the subgroup of patients prescribed gastroprotective agents at baseline, however, the association with GIB was attenuated.

Antiplatelet Drug Use and Breast Cancer Risk in a Prospective Cohort of Postmenopausal Women

BACKGROUND

Epidemiologic evidence is insufficient to draw conclusions on the impact of low-dose aspirin use on breast cancer risk, and the potential impact of other antiplatelet drugs such as clopidogrel needs to be explored.

METHODS

We investigated the association between breast cancer risk and low-dose aspirin or clopidogrel use in the E3N cohort, which includes 98,995 women, with information on breast cancer risk factors collected from biennial questionnaires matched with drug reimbursement data available from 2004. Women with at least two reimbursements of the drug of interest in any previous 3-month period were considered "ever" exposed. Exposure was considered as time-varying and multivariable Cox regression models were used to estimate HRs of breast cancer.

RESULTS

Among 62,512 postmenopausal women followed during 9 years on average, 2,864 breast cancer cases were identified. Compared with never use, a transient higher breast cancer risk was observed during the third year of low-dose aspirin use [HR2-≤3 years of use = 1.49 (1.08-2.07)], followed by a lower risk [HR4+ years of use = 0.72 (0.52-0.99)]. Clopidogrel ever use was associated with a higher breast cancer risk [HR, 1.30 (1.02-1.68)], restricted to estrogen receptor negative (ER-) tumors [HRER+ = 1.14 (0.83-1.57), HRER- = 3.07 (1.64-5.76), P homogeneity = 0.01].

CONCLUSIONS

Low-dose aspirin was associated with a lower breast cancer risk only after several years of use, while ever use of clopidogrel was associated with a higher ER- breast cancer risk.

IMPACT

Antiplatelet drugs are not good pharmacologic candidates for breast cancer prevention.

Aspirin and other nonsteroidal anti-inflammatory drugs, statins and risk of non-Hodgkin lymphoma

Non-steroidal anti-inflammatory drugs (NSAIDs) and statin drugs may protect against the development of non-Hodgkin lymphoma (NHL), but data are limited, particularly for NHL subtypes. Furthermore, some in vitro, animal and epidemiologic data suggest there may be a synergistic effect of these two agents, but there has been no test of this hypothesis in NHL. We evaluated the self-reported use of NSAIDs and statins in a clinic-based study of 1703 NHL patients and 2199 frequency-matched controls. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs), adjusted for potential confounding variables. We observed an inverse association of regular use of low-dose aspirin with risk of NHL (OR = 0.82; 95% CI 0.70-0.96) that was stronger with longer duration of use (P < .01). There were no associations for use of regular or extra-strength aspirin, ibuprofen, other NSAIDs, statins or other cholesterol-lowering drugs with NHL risk, while an inverse association with COX-2 inhibitors was equivocal. There was also no interaction of low-dose aspirin and statins on NHL risk. Inverse associations of similar magnitude to all NHL were observed for regular use of low-dose aspirin with diffuse large B-cell, follicular, marginal zone and all other lymphomas, although not all associations were statistically significant. In conclusion, low-dose aspirin but not regular/extra strength aspirin, other NSAIDs or statin use was associated with lower risk of NHL. Beyond the potential for the primary prevention of NHL, these data also point to a role of anti-platelet or other effects of low-dose aspirin in lymphomagenesis that warrant follow-up.

Aspirin Use and Risk of Breast Cancer: A Meta-analysis of Observational Studies from 1989 to 2019

BACKGROUND

Some evidence shows that aspirin can reduce the morbidity and mortality of different cancers, including breast cancer. Aspirin has become a new focus of cancer prevention and treatment research at present, however, clinical studies found conflicting conclusions of its anticancer characteristics.

MATERIALS AND METHODS

A systematic literature search was performed in 8 electronic databases. The pooled relative risk (RR) with 95% confidence interval (CI) was calculated using the random effects model to estimate the effect of aspirin on breast cancer.

RESULTS

Forty-two published articles with 99,769 patients were identified. The meta-analysis showed a significant decrease in breast cancer risk with aspirin use (RR, 0.92; 95% CI, 0.89-0.96; I² = 72%). Aspirin use decreased the risk of hormone receptor-positive tumors (estrogen receptor [ER]-positive RR, 0.89; 95% CI, 0.82-0.97; I²=54%; progesterone receptor [PR]-positive RR, 0.86; 95% CI, 0.78-0.95; I²=32%; ER- and PR-positive RR, 0.92; 95% CI, 0.85-1.00; I²=45%) and reduced the risk of breast cancer in postmenopausal women (RR, 0.92; 95% CI, 0.86-0.98; I²=59%). Further analysis showed that for the in situ breast cancer, regular-dose and more than 3 years use of aspirin were associated with the reduced risk of breast cancer.

CONCLUSION

This meta-analysis suggested that aspirin may reduce the overall risk of breast cancer, reduce the risk of breast cancer in postmenopausal women, hormone receptor-positive tumors, and in situ breast cancer. Larger, multicenter clinical studies are needed to find the optimal dose range, frequency, and duration of the aspirin use to explore the best benefit-risk ratio.

Analysis of 234 cases of colorectal polyps treated by endoscopic mucosal resection

BACKGROUND

Colorectal polyps refer to all neoplasms that protrude into the intestinal cavity. Researchers believe that 50%-70% of colorectal cancers originate from adenomatous polyps.

AIM

To investigate the endoscopic morphologic features, pathologic types, and clinical situation; evaluate the efficacy and safety of endoscopic mucosal resection (EMR); and guide clinicians in their daily practice.

METHODS

Two hundred thirty-four patients who underwent EMR in our hospital from January 1, 2018 to December 31, 2019 were recruited. Data including sex, age, endoscopic morphology of the polyps, and pathological characteristics were analyzed among groups.

RESULTS

A total of 295 polyps were resected from the 234 subjects enrolled in the study, of which 4 (1.36%) were Yamada type I. There were 75 (25.42%) type II, 101 (34.24%) type III, and 115 (38.98%) type IV adenomas. Among them, 41 were non-adenomas, 110 were low-risk adenomas, 139 were high-risk adenomas, and 5 were carcinomas. The differences in distribution were not statistically significant, with P values greater than 0.05. The risk of cancer significantly increased for polyps ≥ 1 cm in diameter (c² = 199.825, P = 0.00). Regarding the endoscopic morphological features, congestion, erosion, and lobulation were more common on the surface morphology of high-risk adenomas and cancerous polyps (c² = 75.257, P = 0.00), and most of them were Yamada types III and IV. In all, 6 of the 295 polyps could not be removed completely, with a one-time resection rate of 97.97%. There were two cases of postoperative bleeding and no cases of perforation, with an overall complication rate of 0.09%.

CONCLUSION

Colorectal polyps ranging from non-adenomatous polyps, low-risk adenomas, and high-risk adenomas to adenocarcinomas each has their own endoscopic features, while EMR, as a mature intervention, has good safety and operability and should be promoted clinically, especially at the primary care level.

Aspirin might reduce the incidence of breast cancer: An updated meta-analysis of 38 observational studies

BACKGROUND

Many epidemiologic studies were performed to clarify the protective effect of regular aspirin use on breast cancer risks, but the results remain inconsistent. Here, we conducted an updated meta-analysis of 38 studies to quantitatively assess the association of regular aspirin use with risk of breast cancer.

METHOD

We performed a bibliographic database search in PubMed, Embase, Web of Science, Cochrane library, Scopus, and Google Scholar from January 1939 to December 2019. Relative risk (RR) estimates were extracted from eligible case-control and cohort studies and pooled using a random effects model. Subgroup analysis was conducted based on study design, aspirin exposure assessment, hormone receptor status, menopausal status, cancer stage as well as aspirin use duration or frequency. Furthermore, sensitivity and publication bias analyses were performed.

RESULTS

Thirty eight studies of 1,926,742 participants involving 97,099 breast cancer cases contributed to this meta-analysis. Compared with nonusers, the aspirin users had a reduced risk of breast cancer (RR = 0.91, 95% confidence interval [CI]: 0.87-0.95, P value of significance [Psig] < .001) with heterogeneity (P value of heterogeneity [Phet] < .001, I = 82.6%). Subgroup analysis revealed a reduced risk in case-control studies (RR = 0.83, 95% CI: 0.78-0.89, Psig < .001), in hormone receptor positive tumors (RR = 0.91, 95% CI: 0.88-0.94, Psig < .001), in situ breast tumors (RR = 0.79, 95% CI: 0.71-0.88, Psig < .001), and in postmenopausal women (RR = 0.89, 95% CI: 0.83-0.96, Psig = .002). Furthermore, participants who use aspirin for >4 times/wk (RR = 0.88, 95% CI: 0.82-0.96, Psig = .003) or for >10 years (RR = 0.94, 95% CI: 0.89-0.99, Psig = .025) appeared to benefit more from the reduction in breast cancer caused by aspirin.

CONCLUSIONS

Our study suggested that aspirin use might be associated with a reduced risk of breast cancer, particularly for reducing the risk of hormone receptor positive tumors or in situ breast tumors, and the risk of breast cancer in postmenopausal women.

Low-dose aspirin use and risk of contralateral breast cancer: a Danish nationwide cohort study

Observational studies of aspirin use and breast cancer risk have provided inconsistent results. The occurrence of contralateral breast cancer (CBC) among breast cancer survivors may serve as a useful high-risk model to identify preventive drug effects. Using this model, we examined the association between post-diagnosis use of low-dose aspirin and risk of CBC. We identified all women recorded with a first primary breast cancer in the Danish Breast Cancer Cooperative Group Database between 1996 and 2012. Information on drug use, tumor and patient characteristics, treatment, and CBC was obtained from nationwide registries. In the main analysis, we defined time-varying post-diagnosis low-dose aspirin use as two or more prescriptions filled during follow-up and applied a one-year exposure lag. Cox proportional hazard regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between post-diagnosis low-dose aspirin use and CBC risk. Among 52,723 breast cancer patients, 1,444 women developed CBC during a median follow-up of 4.8 years. The adjusted HR for CBC associated with post-diagnosis use of low-dose aspirin was 0.91 (95% CI: 0.75-1.09). We observed no substantial variation in HRs according to pattern of low-dose aspirin use or estrogen receptor status of the first or the contralateral breast cancer. In conclusion, this large nationwide cohort study of breast cancer survivors does not provide strong evidence suggesting an association between post-diagnosis use of low-dose aspirin and risk of CBC.

Aspirin as a potential modality for the chemoprevention of breast cancer: A dose-response meta-analysis of cohort studies from 857,831 participants

BACKGROUND

Previous meta-analyses on the relationship between aspirin use and breast cancer risk have drawn inconsistent results. In addition, the threshold effect of different doses, frequencies and durations of aspirin use in preventing breast cancer have yet to be established.

RESULTS

The search yielded 13 prospective cohort studies (N=857,831 participants) that reported an average of 7.6 cases/1,000 person-years of breast cancer during a follow-up period of from 4.4 to 14 years. With a random effects model, a borderline significant inverse association was observed between overall aspirin use and breast cancer risk, with a summarized RR = 0.94 (P = 0.051, 95% CI 0.87-1.01). The linear regression model was a better fit for the dose-response relationship, which displayed a potential relationship between the frequency of aspirin use and breast cancer risk (RR = 0.97, 0.95 and 0.90 for 5, 10 and 20 times/week aspirin use, respectively). It was also a better fit for the duration of aspirin use and breast cancer risk (RR = 0.86, 0.73 and 0.54 for 5, 10 and 20 years of aspirin use).

METHODS

We searched MEDLINE, EMBASE and CENTRAL databases through early October 2016 for relevant prospective cohort studies of aspirin use and breast cancer risk. Meta-analysis of relative risks (RR) estimates associated with aspirin intake were presented by fixed or random effects models. The dose-response meta-analysis was performed by linear trend regression and restricted cubic spline regression.

CONCLUSION

Our study confirmed a dose-response relationship between aspirin use and breast cancer risk. For clinical prevention, long term (>5 years) consistent use (2-7 times/week) of aspirin appears to be more effective in achieving a protective effect against breast cancer.

Associations between aspirin use and the risk of cancers: a meta-analysis of observational studies

Background

Epidemiological studies have clarified the potential associations between regular aspirin use and cancers. However, it remains controversial on whether aspirin use decreases the risk of cancers risks. Therefore, we conducted an updated meta-analysis to assess the associations between aspirin use and cancers.

Methods

The PubMed, Embase, and Web of Science databases were systematically searched up to March 2017 to identify relevant studies. Relative risks (RRs) with 95% confidence intervals (CIs) were used to assess the strength of associations.

Results

A total of 218 studies with 309 reports were eligible for this meta-analysis. Aspirin use was associated with a significant decrease in the risk of overall cancer (RR = 0.89, 95% CI: 0.87–0.91), and gastric (RR = 0.75, 95% CI: 0.65–0.86), esophageal (RR = 0.75, 95% CI: 0.62–0.89), colorectal (RR = 0.79, 95% CI: 0.74–0.85), pancreatic (RR = 0.80, 95% CI: 0.68–0.93), ovarian (RR = 0.89, 95% CI: 0.83–0.95), endometrial (RR = 0.92, 95% CI: 0.85–0.99), breast (RR = 0.92, 95% CI: 0.88–0.96), and prostate (RR = 0.94, 95% CI: 0.90–0.99) cancers, as well as small intestine neuroendocrine tumors (RR = 0.17, 95% CI: 0.05–0.58).

Conclusions

These findings suggest that aspirin use is associated with a reduced risk of gastric, esophageal, colorectal, pancreatic, ovarian, endometrial, breast, and prostate cancers, and small intestine neuroendocrine tumors.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4156-5) contains supplementary material, which is available to authorized users.

Low-Dose Aspirin or Nonsteroidal Anti-inflammatory Drug Use and Colorectal Cancer Risk: A Population-Based, Case-Control Study

BACKGROUND

A recent comprehensive review concluded that additional research is needed to determine the optimal use of aspirin for cancer prevention.

OBJECTIVE

To assess associations between the use of low-dose aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) and colorectal cancer risk.

DESIGN

Population-based, case-control study.

SETTING

Northern Denmark.

PATIENTS

Patients with first-time colorectal cancer in northern Denmark between 1994 and 2011. Population control participants were selected by risk set sampling.

MEASUREMENTS

Data on drug use, comorbid conditions, and history of colonoscopy were obtained from prescription and patient registries. Use of low-dose aspirin (75 to 150 mg) and nonaspirin NSAIDs was defined according to type, estimated dose, duration, and consistency of use.

RESULTS

Among 10 280 case patients and 102 800 control participants, the adjusted odds ratios (ORs) for colorectal cancer associated with ever use (≥2 prescriptions) of low-dose aspirin and nonaspirin NSAIDs were 1.03 (95% CI, 0.98 to 1.09) and 0.94 (CI, 0.90 to 0.98), respectively. Continuous long-term use (≥5 years) of low-dose aspirin was associated with a 27% reduction in colorectal cancer risk (OR, 0.73 [CI, 0.54 to 0.99]), whereas the overall OR for cumulative long-term use (continuous or noncontinuous) was close to unity. Nonaspirin NSAID use was associated with a substantial reduction in colorectal cancer risk, particularly for long-term, high-intensity use (average defined daily dose ≥0.3) of agents with high cyclooxygenase-2 selectivity (OR, 0.57 [CI, 0.44 to 0.74]).

LIMITATIONS

Data were unavailable on over-the-counter purchases of high-dose aspirin and low-dose ibuprofen or NSAID dosing schedules, there were several comparisons, and the authors were unable to adjust for confounding by some risk factors.

CONCLUSION

Long-term, continuous use of low-dose aspirin and long-term use of nonaspirin NSAIDs were associated with reduced colorectal cancer risk. Persons who continuously used low-dose aspirin comprised only a small proportion of the low-dose aspirin users.

PRIMARY FUNDING SOURCE

Danish Cancer Society, Aarhus University Research Foundation.

Relationship between aspirin use after diagnosis of colorectal cancer and patient survival: a meta-analysis of observational studies

Background:

Epidemiological evidence suggests that use of aspirin after the diagnosis of colorectal cancer can lengthen survival. However, the supporting data vary between studies, and this hypothesis remains controversial. We conducted a meta-analysis to provide a quantitative assessment of the association between use of aspirin after diagnosis of colorectal cancer and patient survival.

Methods:

We searched the Medline and Embase databases up to April 2014 to identify studies related to aspirin use after diagnosis and all-cause mortality or colorectal cancer-specific mortality. Summary effect estimates with 95% confidence intervals (CIs) were derived using a fixed or random effects model, depending on the heterogeneity between the included studies.

Results:

Seven epidemiologic studies that consisted of six cohort studies and one nested case–control study were included in this meta-analysis. The hazard ratio (HR) of the association between aspirin use after colorectal cancer diagnosis and overall mortality, which was reported in five studies, was 0.74 (95% CI, 0.62–0.89) using a random model (heterogeneity test P=0.003, I²=75.3%), and for colorectal cancer-specific mortality (four studies), it was 0.75 (95% CI, 0.51–1.10) using a random model (heterogeneity test P=0.001, I²=84.1%). In addition, we analysed postdiagnosis aspirin use according to whether aspirin was also used before diagnosis. The HR for the overall mortality of patients who did not use aspirin before diagnosis, which was reported in four studies, was 0.84 (95% CI, 0.70–1.00), and for colorectal cancer-specific mortality (three studies), it was 0.79 (95% CI, 0.61–1.02). For those who did use aspirin before diagnosis, the HR for overall mortality (four studies) was 0.88 (95% CI, 0.83–0.93), and for colorectal cancer-specific mortality (three studies), it was 0.80 (95% CI, 0.59–1.09). Subgroup analysis showed that use of aspirin after diagnosis was associated with longer overall survival among patients with the variant PIK3CA gene but not for those with wild-type PIK3CA.

Conclusions:

Based on current evidence, the use of aspirin after diagnosis does not reduce colorectal cancer-specific mortality, but it does reduce all-cause mortality for colorectal cancer patients.