A cohort study investigating aspirin use and survival in men with prostate cancer.

BACKGROUND: Aspirin use has been associated with reduced mortality from cancer including prostate cancer in some studies. A number of anti-cancer mechanisms of aspirin have been proposed, including the inhibition of the cyclooxygenase enzymes, through which aspirin mediates both anti-platelet and anti-inflammatory activities. This cohort study examines associations between pre-diagnostic aspirin use (overall and by dose and dosing intensity) and mortality in men with localised prostate cancer. PATIENTS AND METHODS: Men with stage I-III prostate cancer were identified from Irish National Cancer Registry records, which have been linked to national prescribing data from the Irish General Medical Services scheme. Aspirin use in the year preceding prostate cancer diagnosis was identified from this linked prescription-claims data. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for associations between aspirin use and all-cause and prostate cancer-specific mortality. Associations between prescribed dose and dosing intensity were examined. The presence of effect modification by the type of treatment received and tumour characteristics was also assessed. RESULTS: Two thousand nine hundred and thirty-six men with a diagnosis of stage I-III prostate cancer (2001-2006) were identified (aspirin users, n = 1131). The median duration of patient follow-up was 5.5 years. In adjusted analyses, aspirin use was associated with a small, but non-significant, reduced risk of prostate cancer-specific mortality (HR = 0.88, 95% CI 0.67-1.15). In dose-response analyses, stronger associations with prostate cancer-specific mortality were observed in men with higher aspirin dosing intensity (HR = 0.73, 95% CI 0.51-1.05) and in men receiving >75 mg of aspirin (HR = 0.61, 95% CI 0.37-0.99). Analyses of effect modification by treatment type or tumour characteristics were non-significant. CONCLUSIONS: Consistent with prior studies, aspirin use was associated with a non-significant reduced risk of prostate cancer-specific mortality in men with localised prostate cancer. Men receiving higher doses of aspirin had a statistically significant reduced risk of prostate cancer-specific mortality. These findings regarding an aspirin dose require further investigation.

A nested case-control study of adjuvant hormonal therapy persistence and compliance, and early breast cancer recurrence in women with stage I-III breast cancer.

BACKGROUND: Non-persistence and non-compliance are common in women prescribed hormonal therapy for breast cancer, but little is known about their influence on recurrence. METHODS: A nested case-control study of associations between hormonal therapy non-persistence and non-compliance and the risk of early recurrence in women with stage I-III breast cancer was undertaken. Cases, defined as women with a breast cancer recurrence within 4 years of hormonal therapy initiation, were matched to controls (1 : 5) by tumour stage and age. Conditional logistic regression was used to examine associations between early recurrence and hormonal therapy non-persistence and non-compliance. RESULTS: Ninety-four women with breast cancer recurrence were matched to 458 controls. Women who were non-persistent (≥ 180 days without hormonal therapy) had a significantly increased adjusted recurrence odds ratio (OR) of 2.88 (95%CI 1.11, 7.46) compared with persistent women. There was no significant association between low compliance (OR 1.30; 95% CI 0.74, 2.30) and breast cancer recurrence. CONCLUSION: Hormonal therapy non-persistence is associated with a significantly higher risk of early recurrence in women with stage I-III oestrogen receptor (ER)-positive breast cancer. This finding is consistent with results from randomized studies of hormonal therapy treatment duration and suggests that interventions to target modifiable risk factors for non-persistence are required.

Generalisability of pharmacoepidemiological studies using restricted prescription data.

BACKGROUND: Linking medication databases to disease registries enables population-based pharmacoepidemiology research. In Ireland, country-wide dispensing data is available only from the means-tested government-medical cards scheme. This restriction may impact generalisability of analyses based on these data. AIM: Gender was previously identified as predictor of card status so we aimed to compare women with and without medical cards at the time of ovarian cancer diagnosis. METHODS: Ovarian cancers diagnosed 2001-2010 were identified from the National Cancer Registry Ireland. Age, region, deprivation, smoking, employment and marital status were evaluated using logistic regression for associations with card status. Cumulative incidence of de novo card receipt post-diagnosis was assessed. RESULTS: 1778 (52 %) of 3396 women with incident ovarian cancer had a card at diagnosis (<70:33 %; 70+:87 %). Within those <70, all variables were significantly associated with card status at diagnosis. 52 % of those without a card at diagnosis received one post-diagnosis. CONCLUSIONS: Although medical card coverage within ovarian cancer patients is similar to the general population, various factors predict card status. Particularly within those under 70, external validity needs to be considered when interpreting pharamcoepidemiological analyses using these data.