Long-term use of calcium channel blocking drugs and breast cancer risk in a prospective cohort of US and Puerto Rican women

Abstract

BackgroundIn a recent case–control study, long-term use of calcium channel blocking drugs was associated with a greater-than-twofold increased breast cancer risk. If prospectively collected data confirm that calcium channel blocker use increases breast cancer risk, this would have major implications for hypertension treatment. The objective of this study was to determine whether women using calcium channel blockers for 10 years or more were at increased risk of developing breast cancer compared with women not using calcium channel blockers.MethodsThe Sister Study is a prospective volunteer cohort study of women from the USA and Puerto Rico designed to evaluate environmental and genetic risk factors for breast cancer. Beginning in 2003, women between the ages of 35 and 74 were recruited. They were eligible to participate if they had a sister with breast cancer but had not been diagnosed with breast cancer themselves. In total, 50,884 women enrolled in the cohort between 2003 and 2009; 50,757 women with relevant baseline data and available follow-up data are included in this study. The exposure of interest is current use of calcium channel blocking drugs and the reported duration of use at entry into the cohort. Secondary exposures of interest were the duration and frequency of use for all other subclasses of antihypertensive drugs. Our main outcome is a self-reported diagnosis of breast cancer during the study follow-up period. With patient permission, self-reported diagnoses were confirmed using medical records.ResultsResults showed 15,817 participants were currently using an antihypertensive drug, and 3316 women were currently using a calcium channel blocker at study baseline; 1965 women reported a breast cancer diagnosis during study follow-up. Using Cox proportional hazards modeling, we found no increased risk of breast cancer among women who had been using calcium channel blockers for 10 years or more compared with never users of calcium channel blockers (HR 0.88, 95 % CI 0.58–1.33).ConclusionsWe saw no evidence of increased risk of breast cancer from 10 years or more of current calcium channel blocker use. Our results do not support avoiding calcium channel blocking drugs in order to reduce breast cancer risk.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-016-0720-6) contains supplementary material, which is available to authorized users.

Hypertension and breast cancer risk: a systematic review and meta-analysis

“…In addition, with regard to the design of case-control, potential selection bias, recall bias, and confounding by indication might lead to a biased estimation about the association. Notably, previous meta-analysis and large long-term follow-up cohort studies606162 had confirmed the null association between antihypertensive drugs and breast cancer risk to a large extent. According to the analysis above, antihypertensive medications use was unlikely to alter results in this meta-analysis substantially.…”

Antihypertensive drug use and breast cancer risk: a meta-analysis of observational studies

“…Three additional articles [ 13 , 14 , 18 ] were included from the reference review. Finally, a total of 21 studies [ 2 , 9 – 13 , 15 – 27 , 52 , 53 ] published from 1996 to 2016 were included. The study selection process is depicted in Figure 1 .…”

Calcium channel blockers and breast cancer incidence: An updated systematic review and meta-analysis of the evidence

“…That long-term drug effects often emerge beyond the length of a typical RCT has also been demonstrated for the potential inverse association between low-dose aspirin and colorectal cancer (76), highlighting the important role of well-designed observational studies as part of effective post-marketing surveillance. Subsequent to database searching, a study from Puerto Rico corroborates a lack of association with long-term use (64), while a study from Spain indicates that use of CCBs beyond five years may be associated with developing breast cancer, especially for overweight or postmenopausal women (65). Incorporation of these data into the meta-analyses does not materially change the results.…”

“…The larger number of studies included in our review relative to previous meta-analyses is attributable to wider eligibility criteria, and that several studies have been published subsequent to the earlier reviews being conducted. Since these reviews were published, there has been further data emerging with longer-term followup (34,35,37,41,42,44,49,51) and subsequent to database searching (64,65), notably including data from outside North America and Europe. This was partly in response to the 2013 study by Li et al (46); it is thus timely to reassess the literature to check if the likely risk has moved toward providing a more unequivocal answer to this controversy.…”