32 / 35
Page 100
Notes:
conferenceseries
.com
Volume 7, Issue 5 (Suppl)
Epidemiology (Sunnyvale), an open access journal
ISSN: 2161-1165
Epidemiology 2017
October 23-25, 2017
EPIDEMIOLOGY & PUBLIC HEALTH
October 23-25, 2017 | Paris, France
6
th
International Conference on
DE NOVO POST-DIAGNOSIS VITAMIN D USE AND BREAST CANCER MORTALITY
Jamie Madden
a
, Kathleen Bennett
b
, Laura Murphy
b
, Ian Barron
c
and
Lina Zgaga
d
a
RCSI, Ireland
b
Health Research Board, Ireland
c
Johns Hopkins Baltimore, USA
d
Trinity College, Ireland
Introduction:
Experimental data suggests a protective effect of vitamin D on breast cancer progression but epidemiological
evidence is emerging. A recent meta-analysis however suggested a large reduction in breast cancer mortality (HR: 0.65; 95%
CI: 0.44-0.98)) in those in the highest quartile of circulating 25(OH) D levels compared to the lowest quartile when measured
at diagnosis.
Aim and Methods:
In this study we investigate, in a large linked national cancer registry and prescribing database in Ireland,
associations between vitamin D use initiated after a diagnosis (de novo) in women with stage I-III breast cancer and all-cause
and breast cancer- specific mortality (n=5417); see Figure 1. Initiation of vitamin D post-diagnosis was identified from the
linked national prescription data (n=2570 (48%) initiating vitamin D). Multivariate cox proportional hazards models were
used to estimate hazard ratios (HRs) for associations between de novo vitamin D use and mortality while adjusting for patient,
tumour characteristics and treatment.
Results:
Initiation of vitamin D was significantly higher among those in receipt of statin, bisphosphonate and anti-estrogen
therapy. Those with a perceived better prognosis also had a higher initiation rate (e.g. ER/PR positive and HER2 negative). After
appropriate adjustment for confounders, there was a significant association between de novo vitamin D use post-diagnosis
(yes/no time-varying) and, breast cancer-specific (HR: 0.69; 95% CI: 0.55-0.86) and all-cause mortality (HR: 0.76; 95% CI:
0.65-0.90). After additional analysis correcting for imbalance between treatment groups using propensity score analysis, a
significant association persisted between vitamin D use post-diagnosis and breast cancer-specific mortality (HR: 0.70; 95% CI:
0.52-0.93), but not for all-cause mortality (HR: 0.82; 95% CI: 0.67-1.01).
Conclusion:
Breast cancer-specific mortality in de novo vitamin D users post-diagnosis was significantly lower than non-
users. Vitamin D has the potential as a non-toxic treatment to improve survival in breast cancer patients.
Epidemiology (Sunnyvale) 2017, 7:5(Suppl)
DOI: 10.4172/2161-1165-C1-018