Aspirin use and survival after the diagnosis of breast cancer: a population-based cohort study

Abstract

Background:Aspirin use has been associated with a reduced cancer incidence and fewer deaths from cancer. This study examined whether women with breast cancer prescribed aspirin postdiagnosis had improved survival.Methods:An observational, population cohort study was undertaken using data linkage of cancer registry, dispensed prescriptions and death records in Tayside, Scotland. All community prescriptions for aspirin in women with breast cancer were extracted and use postdiagnosis for each individual examined using Cox's proportional hazard models. The main outcome measures were all-cause mortality and breast cancer-specific mortality.Results:Four thousand six hundred and twenty-seven patients diagnosed with breast cancer between 1 January 1998 and 31 December 2008 were followed up until 28 February 2010. Median age at diagnosis was 62 (IQR 52–74). One thousand eight hundred and two (39%) deaths were recorded, with 815 (18%) attributed to breast cancer. One thousand and thirty-five (22%) patients were prescribed aspirin postdiagnosis. Such aspirin use was associated with lower risk of all-cause mortality (HR=0.53, 95% CI=0.45–0.63, P<0.001) and breast cancer-specific mortality (HR=0.42, 95% CI=0.31–0.55, P<0.001) after adjusting for age, socioeconomic status, TNM stage, tumour grade, oestrogen receptor status, surgery, radiotherapy, chemotherapy, adjuvant endocrine therapy and aspirin use prediagnosis.Conclusions:Aspirin use postdiagnosis of breast cancer may reduce both all-cause and breast cancer-specific mortality. Further investigation seeking a causal relationship and which subgroups of patients benefit most await ongoing randomised controlled trials.

Low-dose aspirin use and survival in breast cancer patients: A nationwide cohort study

“…It is possible that the extended breast cancer survival observed for aspirin users in these studies may be due to higher PTSG-2 inhibiting doses as opposed to doses which inhibit platelet function. Our study also contradicts the results from a recent Scottish study which observed an approximate 60% reduction in cancer mortality among users of low-dose aspirin use after diagnosis (adjusted HR 0.42, 95% CI 0.31, 0.55) [11]. Like ours, this study utilised linked cancer registration and dispensed medication data, but their findings may have partly been affected by reverse causation as they utilised an unlagged start/stop time-varying covariate approach which allocated cancer-specific deaths to the aspirin user or nonuser group on the basis of whether they had an aspirin prescription that covered the time of death.…”

“…26 breast cancer deaths) [9], used patient self-report of aspirin use (which may be subject to recall bias) [9,10] and did not provide information on aspirin dose; therefore it is unclear whether the observed inverse associations are due to potential anti-platelet effects of aspirin. More recently, a study of 4,627 breast cancer patients resident in the Tayside area of Scotland reported a 58% reduction in breast cancer death associated with post-diagnostic low-dose aspirin use [11]. This particular analysis may have been partly affected by reverse causation [12], such that the true association between aspirin and cancer-specific mortality may have been exaggerated if aspirin was withdrawn from cancer patients in whom death was suspected to be imminent [11].…”

“…More recently, a study of 4,627 breast cancer patients resident in the Tayside area of Scotland reported a 58% reduction in breast cancer death associated with post-diagnostic low-dose aspirin use [11]. This particular analysis may have been partly affected by reverse causation [12], such that the true association between aspirin and cancer-specific mortality may have been exaggerated if aspirin was withdrawn from cancer patients in whom death was suspected to be imminent [11]. In contrast to these findings, four other observational studies found little evidence of an association between aspirin use after diagnosis and breast cancer survival or recurrence [13][14][15][16][17].…”

De NovoPost-Diagnosis Aspirin Use and Mortality in Women with Stage I–III Breast Cancer

“…In breast cancer, a number of observational studies have examined associations between aspirin use and disease recurrence or death (4)(5)(6)(7)(8)(9)(10)(11)(12), with three reporting statistically significant reductions in breast cancer-related mortality (5)(6)(7). Most of these studies included women taking aspirin before their breast cancer diagnosis and did not distinguish between pre-and post-diagnostic initiation of exposure in their analyses (5)(6)(7)(8)(9).…”

“…Most of these studies included women taking aspirin before their breast cancer diagnosis and did not distinguish between pre-and post-diagnostic initiation of exposure in their analyses (5)(6)(7)(8)(9). Only two previous studies have examined associations between de novo post-diagnostic aspirin use and breast cancer outcomes (11,12).…”