Cigarette Smoking, Obesity, Physical Activity, and Alcohol Use As Predictors of Chemoprevention Adherence in the National Surgical Adjuvant Breast and Bowel Project P-1 Breast Cancer Prevention Trial

National Surgical Adjuvant Breast and Bowel Project (NSABP) Operations and Biostatistical Centers, University of Pittsburgh, PA, USA.
Cancer Prevention Research (Impact Factor: 4.44). 08/2011; 4(9):1393-400. DOI: 10.1158/1940-6207.CAPR-11-0172
Source: PubMed


The double-blind, prospective, National Surgical Adjuvant Breast and Bowel Project (NSABP) Breast Cancer Prevention Trial (BCPT) showed a 50% reduction in the risk of breast cancer for tamoxifen versus placebo, yet many women at risk of breast cancer do not adhere to the 5-year course. This first report of the rich BCPT drug adherence data examines predictors of adherence. Between June, 1992 and September, 1997 13,338 women at high risk of breast cancer were randomly assigned to 20 mg/d tamoxifen versus placebo; we analyzed the 11,064 enrolled more than 3 years before trial unblinding. Primary endpoint was full drug adherence (100% of assigned pills per staff report, excluding protocol-required discontinuation) at 1 and 36 months; secondary was adequate adherence (76%-100%). Protocol-specified multivariable logistic regression tested lifestyle factors, controlling for demographic and medical predictors. About 13% were current smokers; 60% were overweight/obese; 46% had moderate/heavy physical activity; 21%, 66%, 13% drank 0, 0-1, 1+ drinks per day, respectively; 91% were adequately adherent at 1 month; and 79% were at 3 years. Alcohol use was associated with reduced full adherence at 1 month (P = 0.016; OR = 0.79 1+ vs. 0), as was college education (P <0.001; OR = 0.78 vs. high school); age (P < 0.001; OR = 1.4 age 60+) and per capita household annual income (P < 0.001; OR = 1.2 per $30,000) with increased adherence. Current smoking (P = 0.003; OR = 0.75), age (P = 0.024, OR = 1.1), college education (P = 0.037; OR = 1.4), tamoxifen assignment (P = 0.031; OR = 0.84), and breast cancer risk (P <.001; OR = 1.5 high vs. low) predicted adequate adherence at 36 months. There were no significant associations with obesity or physical activity. Alcohol use and smoking might indicate a need for greater adherence support.

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Available from: William MP Klein, Oct 03, 2015
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    • "In some settings, non-adherence has been associated with adverse health behaviours such as tobacco smoking and excess alcohol consumption (Land et al., 2011). Increased prescription of oral therapies has also led to lower adherence, raising concerns about potential for increased non-adherence as use of oral therapies increases (Partridge et al., 2002: 2003; Atkins et al., 2006; Chlebowski & Geller, 2006; Partridge et al., 2008; Ruddy 1676 & Partridge, 2009). "
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    • "Smoking has long been known to be a risk factor while obesity has more recently been recognized as one. Together they account for roughly half of all cancer cases (Ott et al. 2011, Brand et al. 2011, Land et al. 2011, Li et al. 2011a, Boniol and Autier 2010, Giovannucci et al. 2010, Gotay 2010, Khan et al. 2010, Teucher et al. 2009). Since these habits are easier said than done, policies that make unhealthy lifestyle choices difficult and expensive while making healthier ones easier and cheaper will be a step in the right direction. "
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    ABSTRACT: Treatment with the selective estrogen receptor modulator (SERM) tamoxifen for 5 years has produced dramatic breast cancer-related benefits in (a) the adjuvant setting, with 30% to 50% reductions in recurrence, contralateral disease, and mortality and (b) the prevention setting of healthy high-risk women, where tamoxifen reduces the risk of invasive and noninvasive breast cancer by 50%. Despite these striking data, adherence to tamoxifen is low, and low adherence is associated with poor survival. Although toxicity is a major predictor of poor adherence after starting therapy, pretreatment (baseline) predictors of poor tamoxifen adherence have been minimally studied. The adherence-survival link underscores the critical need to identify early predictors of poor adherence, and recent work is beginning to address this need. A major baseline predictor of poor adherence to prevention is current smoking, which is interestingly absent from studies of adherence to adjuvant therapy. Other important prevention adherence factors include breast cancer risk, extremes of age, non-white ethnicity, low socioeconomic status, and alcohol use. The strongest adjuvant therapy predictors are age (especially very young), ethnicity, and socioeconomic status. Future studies involving prospective systematic evaluation of these and other potential predictors in endocrine chemoprevention (e.g., other SERMs and aromatase inhibitors) are critical, as is the development of effective/targeted interventions to improve adherence and thus treatment outcomes in at-risk women.
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