A Tablet a Day Can Keep Breast Cancer at Bay

“Our analysis, which takes into account records of almost 1400 women with breast cancer, clearly shows that recurrence rates of breast cancer are lowest among the women who stick to prescribed medications after other interventions such as surgery”, explained Dr Kathleen Bennett, from the Department of Pharmacology & Therapeutics, Trinity College Dublin. “When you either stop taking your hormonal treatments completely (known as non-persistence), or you take them inconsistently (known as non-compliance), the evidence points to an increased risk of your breast cancer coming back.” 

Dr Ian Barron, lead author on the paper from the Department of Pharmacology & Therapeutics, Trinity College Dublin, and now working at Johns Hopkins said, “The study shows that simply prescribing hormonal treatment after surgery (for those cancers that are responsive to hormone therapy) is not enough. The side effects of the drugs can be powerful enough to turn people off taking the medication. Other studies have shown that up to 30% of women will discontinue hormone treatment, with another 20% not taking as many as one in five of their doses. Our data is the first to show conclusively that those who do stick with taking the drugs have a lower chance of their breast cancer coming back.” 

“Hence a structured approach to interventions, such as, the early identification of women experiencing side-effects, the availability of effective supportive pharmacologic and psychological care, and the timely switching to alternative hormonal therapies could make a significant impact on patients adhering to their medication, and thereby improve their chances of living longer”. The TCD research team plan to do a detailed cost benefit analysis of what interventions might make the most impact and at the lowest cost and hope to present those findings later in the year at the International Society for Pharmacoeconomics and Outcomes Research (ISPOR) Conference in Dublin in November. The study was conducted using patient records from the National Cancer Registry Ireland (NCRI), which are linked to prescription dispensing data from Ireland’s Health Services Executive (HSE) Primary care reimbursement services (PCRS) pharmacy claims database. The research involved 1,376 women with stage I-III oestrogen receptor positive breast cancer. The study was funded by the Health Research Board. The full paper is available from the British Journal of Cancer at: http://www.nature.com/bjc/journal/vaop/ncurrent/full/bjc2013518a.html  

Notes:

The NCRI records detailed information on all incident cancers diagnosed in the population usually resident in Ireland. Information on patient characteristics, tumour details, treatment received and death is collected by trained hospital-based tumour registration officers (TRO) from multiple sources including pathology and radiology reports, medical records and death certificates. The HSE-PCRS is responsible for reimbursement of claims made under the General Medical Services (GMS) community drug scheme. All prescriptions for tamoxifen, toremifene, anastrozole, letrozole and exemestane, dispensed to women from the time of breast cancer diagnosis to the end of follow up, were identified from the PCRS database. The date of dispensing, type of hormonal therapy and number of days’ supply on each prescription were abstracted. Using this data a longitudinal daily history of hormonal therapy availability was assembled for each woman by assigning the days’ supply from each prescription to sequential days from the date of dispensing. These longitudinal daily histories of hormonal therapy availability were used to calculate three measures of medication taking behaviour. (i) Persistence:  or the length of time that they continue to properly take their medication.  (ii) Compliance: the average number of days per week that they took their medication and, (iii) Cumulative exposure: which takes account of both persistence and compliance factors.