PURPOSE Nonadherence to long-term treatments is often under-recognized by physicians and there is no gold standard for its assessment. In breast cancer, nonadherence to tamoxifen therapy after surgery constitutes a major obstacle to optimal outcomes. We sought to evaluate the rate of biochemical nonadherence to adjuvant tamoxifen using serum assessment and to examine its effects on short-term, distant disease-free survival (DDFS). PATIENTS AND METHODS We studied 1,177 premenopausal women enrolled in a large prospective study (CANTO/NCT01993498). Definition of biochemical nonadherence was based on a tamoxifen serum level < 60 ng/mL, assessed 1 year after prescription. Self-reported nonadherence to tamoxifen therapy was collected at the same time through semistructured interviews. Survival analyses were conducted using an inverse probability weighted Cox proportional hazards model, using a propensity score based on age, staging, surgery, chemotherapy, and center size. RESULTS Serum assessment of tamoxifen identified 16.0% of patients (n = 188) below the set adherence threshold. Patient-reported rate of nonadherence was lower (12.3%). Of 188 patients who did not adhere to the tamoxifen prescription, 55% self-reported adherence to tamoxifen. After a median follow-up of 24.2 months since tamoxifen serum assessment, patients who were biochemically nonadherent had significantly shorter DDFS (for distant recurrence or death, adjusted hazard ratio, 2.31; 95% CI, 1.05 to 5.06; P = .036), with 89.5% of patients alive without distant recurrence at 3 years in the nonadherent cohort versus 95.4% in the adherent cohort. CONCLUSION Therapeutic drug monitoring may be a useful method to promptly identify patients who do not take adjuvant tamoxifen as prescribed and are at risk for poorer outcomes. Targeted interventions facilitating patient adherence are needed and have the potential to improve short-term breast cancer outcomes.

PURPOSE Adverse effects of breast cancer treatment can negatively affect survivors’ work ability. Previous reports lacked detailed clinical data or health-related patient-reported outcomes (PROs) and did not prospectively assess the combined impact of treatment and related sequelae on employment. METHODS We used a French prospective clinical cohort of patients with stage I-III breast cancer including 1,874 women who were working and ≥ 5 years younger than legal retirement age (≤ 57 years) at breast cancer diagnosis. Our outcome was nonreturn to work (non-RTW) 2 years after diagnosis. Independent variables included treatment characteristics as well as toxicities (Common Toxicity Criteria Adverse Events [CTCAE] v4) and PROs (European Organization for Research and Treatment of Cancer [EORTC] Quality of life Questionnaires, Breast cancer module [QLQ-BR23] and Fatigue module [QLQ-FA12], Hospital Anxiety and Depression Scale) collected 1 year after diagnosis. Logistic regression models assessed correlates of non-RTW, adjusting for age, stage, comorbidities, and socioeconomic covariates. RESULTS Two years after diagnosis, 21% of patients had not returned to work. Odds of non-RTW were significantly increased among patients treated with combinations of chemotherapy and trastuzumab (odds ratio [OR] v chemotherapy-hormonotherapy: for chemotherapy-trastuzumab, 2.01; 95% CI, 1.18 to 3.44; for chemotherapy-trastuzumab-hormonotherapy, 1.62; 95% CI, 1.10 to 2.41). Other significant associations with non-RTW included grade ≥ 3 CTCAE toxicities (OR v no, 1.59; 95% CI, 1.15 to 2.18), arm morbidity (OR v no, 1.59; 95% CI, 1.19 to 2.13), anxiety (OR v no, 1.47; 95% CI, 1.02 to 2.11), and depression (OR v no, 2.29; 95% CI, 1.34 to 3.91). CONCLUSION Receipt of systemic therapy combinations including trastuzumab was associated with increased odds of non-RTW. Likelihood of unemployment was also higher among patients who reported severe physical and psychological symptoms. This comprehensive study identifies potentially vulnerable patients and warrants supportive interventional strategies to facilitate their RTW.

BackgroundMany breast cancer (BC) survivors are employed at diagnosis and are expected to return to work after treatment. Among them, around 50% are overweight or obese. There are limited data about the impact of body weight on their ability to return to work.MethodsWe used data from CANcer TOxicity (NCT01993498), a prospective, multicentre cohort of women with stage I–III BC. Professionally active women who were ≥5 years younger than retirement age were identified. Multivariable logistic regression models examined associations of body mass index (BMI) at diagnosis and subsequent weight changes with non-return to work 2 years after diagnosis, adjusting for psychosocial, treatment and behavioural characteristics.ResultsAmong 1869 women, 689 were overweight or obese. Overall, 398 patients (21.3%) had not returned to work 2 years after diagnosis. Non-return to work was more likely for overweight or obese than underweight or normal weight patients (adjusted OR (aOR) 1.32; 95% CI, 1.01 to 1.75; p=0.045). Weight loss (≥5%) was observed in 15.7% overweight or obese and 8.7% underweight or normal weight patients and was associated with significant increases in physical activity only among overweight or obese patients (mean change, +4.7 metabolic-equivalent-of-task-hour/week; 95% CI +1.9 to +7.5). Overweight or obese patients who lost weight were more likely to return to work compared with those who did not lose weight (aOR of non-return-to-work, 0.48; 95% CI 0.24 to 0.97, p=0.0418), whereas weight loss was associated with increased odds of non-return to work among underweight or normal weight women (aOR 2.07; 95% CI 1.20 to 3.56, p=0.0086) (pinteractionBMI×weight changes=0.0002). The continuous trend of weight gain on non-return to work was significant for overweight or obese patients (aOR for one-percent-unit difference, 1.03; 95% CI 1.01 to 1.06, p=0.030).ConclusionsExcess weight may be a barrier to return to work. Among overweight or obese BC survivors, weight loss was associated with higher rates of return to work, whereas further weight gain was associated with lower likelihood of return to work. Employment outcomes should be evaluated in randomised studies of weight management.