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Tamoxifen is an important targeted endocrine therapy in breast cancer. However, side effects and early discontinuation of tamoxifen remains a barrier for obtaining the improved outcome benefits of long-term tamoxifen treatment. Biomarkers predictive of tamoxifen side effects remain unidentified. The objective of this prospective population-based study was to investigate the value of tamoxifen metabolite concentrations as biomarkers for side effects. A second objective was to assess the validity of discontinuation rates obtained through pharmacy records with the use of tamoxifen drug monitoring. Longitudinal serum samples, patient-reported outcome measures and pharmacy records from 220 breast cancer patients were obtained over a 6-year period. Serum concentrations of tamoxifen metabolites were measured by LC–MS/MS. Associations between metabolite concentrations and side effects were analyzed by logistic regression and cross table analyses. To determine the validity of pharmacy records we compared longitudinal tamoxifen concentrations to discontinuation rates obtained through the Norwegian Prescription database (NorPD). Multivariable Cox regression models were performed to identify predictors of discontinuation. At the 2nd year of follow-up, a significant association between vaginal dryness and high concentrations of tamoxifen, Z-4′-OHtam and tam-NoX was identified. NorPD showed a tamoxifen-discontinuation rate of 17.9% at 5 years and drug monitoring demonstrated similar rates. Nausea, vaginal dryness and chemotherapy-naive status were significant risk factors for tamoxifen discontinuation. This real-world data study suggests that measurements of tamoxifen metabolite concentrations may be predictive of vaginal dryness in breast cancer patients and verifies NorPD as a reliable source of adherence data.

After a cancer diagnosis, patients often change their lifestyle in order to improve health. The aim of this study was to examine whether women with breast cancer had changed their diet two years after the diagnosis, and to compare their diet with that of healthy female blood donors.Patients (n = 180), median age 58 years (range 37-78), and 101 controls, median age 57 years (age 43-75) answered questions about consumption of alcohol, 36 different food items, and information like age, body mass index (BMI), marital status, and years of education.Forty patients (22%) had changed their diet. Comparing all patients with controls, significantly more patients avoided alcohol, p = 0.0005, and 3 of 36 food items; smoked food, p = 0.04, and milk and other dairy products, p = 0.02 and p =0.0001, respectively. Based on BMI, 50% of all the patients reported overweight or obesity. Breast cancer treatment explained 5.7% of the total variance in scores for changing diet, where chemotherapy was the sole significant predictor, p = 0.04.Two years after a breast cancer diagnosis, most women (78%) maintained their diet, which was largely similar to the controls. Fifty percent of the patients reported overweight or obesity.

Tamoxifen is an important targeted endocrine therapy in breast cancer. However, side effects and early discontinuation of tamoxifen remains a barrier for obtaining the improved outcome benefits of long-term tamoxifen treatment. Biomarkers predictive of tamoxifen side effects remain unidentified. The objective of this prospective population-based study was to investigate the value of tamoxifen metabolite concentrations as biomarkers for side effects. A second objective was to assess the validity of discontinuation rates obtained through pharmacy records with the use of tamoxifen drug monitoring.Longitudinal serum samples, patient-reported outcome measures and pharmacy records from 220 breast cancer patients were obtained over a 6-year period. Serum concentrations of tamoxifen metabolites were measured by LC-MS/MS. Associations between metabolite concentrations and side effects were analyzed by logistic regression and cross table analyses. To determine the validity of pharmacy records we compared longitudinal tamoxifen concentrations to discontinuation rates obtained through the Norwegian Prescription database (NorPD). Multivariable Cox regression models were performed to identify predictors of discontinuation.At the 2nd year of follow-up, a significant association between vaginal dryness and high concentrations of tamoxifen, Z-4'-OHtam and tam-NoX was identified. NorPD showed a tamoxifen-discontinuation rate of 17.9% at 5 years and drug monitoring demonstrated similar rates. Nausea, vaginal dryness and chemotherapy-naive status were significant risk factors for tamoxifen discontinuation.This real-world data study suggests that measurements of tamoxifen metabolite concentrations may be predictive of vaginal dryness in breast cancer patients and verifies NorPD as a reliable source of adherence data.

Purpose Adjuvant endocrine therapy (ET) in breast cancer reduces recurrence risk and increases overall survival. The aim of the study was to quantify non-adherence and discontinuation to ET in postmenopausal women with breast cancer, and identify possible clinical or social risk factors. Methods Women with hormone-receptor positive breast cancer (N = 138), mean age 58 (SD 9.3) years, filled in 4 questionnaires within 1–12, 24, 36 and 48–60 months after surgery; Subjective Health Complaints Inventory (SHC), Functional Assessment of Cancer Therapy-Social Support Subscale (FACT-ES), and Quality of Patient Information Questionnaire (QPI). Adherence to Tamoxifen (Tam) or Aromatase Inhibitors (AI) was examined using the self-reported Morisky Medication Adherence Scale (MMAS-8) and data from the Norwegian Prescription Database (NorPD). Kaplan-Meier curves and Cox proportional hazards regression models estimated adherence to ET. Results The estimate of discontinued ET within 60 months was 38%. Self-reported discontinuation was 7% compared with 25% from the NorPD. Being overweight or obese were significantly time dependent factors predictive for discontinuing ET, p = 0.025. Conclusion Closer follow-ups, tailor-made information about the proven benefits of ET, and keeping a normal body mass index (BMI) may improve adherence to ET in postmenopausal women with breast cancer.

Women with breast cancer often attribute their health problems as side effects caused by oncological treatments. The aim of the study was to examine and compare self-reported health complaints (SHC) in postmenopausal patients with breast cancer to healthy controls.Women with breast cancer (N = 196) filled in 5 questionnaires 1-2 years after surgery; SHC Inventory, Functional Assessment of Cancer Therapy-Endocrine Subscale (FACT-ES), Fatigue - Functional Assessment of Cancer Therapy-Fatigue subscale (FACIT-F), Fatigue Visual Analog Scale (Fatigue VAS), and Hospital Anxiety and Depression Scale (HADS). Controls comprised 101 blood donors who reported on the questionnaires except for HADS. Bonferroni adjustment and p 0.0017 was considered statistically significant for SHC Inventory, p 0.05 for the remaining questionnaires.The patients, mean age 58.0 (SD 9.5), reported significantly more self-reported health complaints, whereof 6 of 29 complaints were significantly elevated compared to the controls, mean age 57.0 (SD 5.8) (p 0.001). HADS scores in patients fell into normal range, mean 6.3 (SD 5.7). A subgroup of 48 patients experienced more frequent and severe symptoms in all the questionnaires compared to the remaining 148 patients, and the 101 controls. Among the patients, fatigue, anxiety and depression explained 49% of the total variance in self-reported health complaints (p ≤ 0.001).Most women with breast cancer (76%) reported health complaints equal to the healthy controls. Fatigue, anxiety and depression, not oncological treatments, were significant predictors for the complaints.

Several studies have shown that uncertainty about disease and fear of disease progression affects psychosocial adjustment and quality of life. The purpose of this study was to validate a Norwegian short version of the "The Mishel Uncertainty in Illness Scale" (SF-MUIS) and to examine the impact of uncertainty in illness in breast cancer patients.209 patients in breast cancer treatment completed questionnaires for SF-MUIS, Hospital Anxiety and Depression Scale (HADS), the Functional Assessment of Cancer Therapy-Breast (FACT-ES), and eight questions concerning quality of the patient information provided (IQP). Relationship between scores on uncertainty in illness and anxiety, depression, social support, emotional well-being, the quality of patient information provided, and age were studied by multiple regression analyses.Ordinal coefficient alpha for the Norwegian version of SF-MUIS was 0.70. Scores on SF-MUIS correlated significantly with scores on HADS (P = 0.001), FACT-ES (P = 0.001), and IQP (P = 0.001) indicating good convergent validity. The patients reported a moderate degree of uncertainty in illness. However, those who had been diagnosed with breast cancer for a year, reported higher scores than those newly diagnosed (P=0.0001). Information provided was the sole significant predictor of illness uncertainty (P=0.0001).The results of the present study confirm that the Norwegian version of the SF-MUIS is a suitable tool for assessment of uncertainty in breast cancer patients, who reported a moderate degree of uncertainty in illness.

1 Stavanger University Hospital, Department of Surgery, Section for Breast and Endocrine Surgery, Stavanger, Norway, 2 University of Bergen, Institute of Medicine, Bergen, Norway, 3 University of Bergen, Institute of Surgical Sciences, Bergen, Norway, 4 Haukeland University Hospital, Department of Breast and Endocrine Surgery, Bergen, Norway and 5 Haukeland University Hospital, Hormonlaboratoriet, Bergen, Norway