PURPOSE: The use of cytochrome P450 2D6-inhibiting drugs (CYP2D6 inhibitors) during tamoxifen treatment leads to a decrease in plasma concentration of endoxifen, the major active tamoxifen... Show morePURPOSE: The use of cytochrome P450 2D6-inhibiting drugs (CYP2D6 inhibitors) during tamoxifen treatment leads to a decrease in plasma concentration of endoxifen, the major active tamoxifen metabolite. Concomitant use of CYP2D6 inhibitors, such as selective serotonin reuptake inhibitors, as well as low tamoxifen adherence may negatively impact tamoxifen efficacy in breast cancer patients. The objectives of this study were to relate concomitant CYP2D6 inhibitor use and tamoxifen adherence to breast cancer event-free time (EFT). PATIENTS AND METHODS: Data were from PHARMO and included a community pharmacy dispensing database; PALGA, a nationwide pathology database; and the Dutch Medical Register in the Netherlands. Breast cancer patients treated with adjuvant tamoxifen between 1994 and 2006 were included. A Cox proportional hazards model with a time-dependent definition for concomitant CYP2D6 inhibitor exposure was used. Adherence calculated over the first year after tamoxifen initiation was related to breast cancer events in the following period. RESULTS: In total, 1,962 breast cancer patients using tamoxifen were included, among whom 150 (7.6%) frequently used a CYP2D6 inhibitor during tamoxifen treatment. No association between concomitant CYP2D6 inhibitor use and breast cancer recurrence was observed (adjusted hazard ratio [HR], 0.87; 95% CI, 0.42 to 1.79; P = .69). Poor tamoxifen adherence was associated with lower EFT (adjusted HR, 0.987; 95% CI, 0.975 to 0.999; P = .029). CONCLUSION: This observational study did not show an association between concomitant CYP2D6 inhibitor use and breast cancer recurrence among patients treated with adjuvant tamoxifen despite the strong biologic rationale. This study shows, to the best of our knowledge for the first time, that poor tamoxifen adherence is associated with an increased risk of breast cancer events. Show less
Hage, J.A. van der; Mieog, J.S.D.; Vijver, M.V. van de; Bartelink, H.; Putter, H.; Velde, C.J.H. van de 2010
BACKGROUND: After surgery for intermediate-risk endometrial carcinoma, the vagina is the most frequent site of recurrence. This study established whether vaginal brachytherapy (VBT) is as effective... Show moreBACKGROUND: After surgery for intermediate-risk endometrial carcinoma, the vagina is the most frequent site of recurrence. This study established whether vaginal brachytherapy (VBT) is as effective as pelvic external beam radiotherapy (EBRT) in prevention of vaginal recurrence, with fewer adverse effects and improved quality of life. METHODS: In this open-label, non-inferiority, randomised trial undertaken in 19 Dutch radiation oncology centres, 427 patients with stage I or IIA endometrial carcinoma with features of high-intermediate risk were randomly assigned by a computer-generated, biased coin minimisation procedure to pelvic EBRT (46 Gy in 23 fractions; n=214) or VBT (21 Gy high-dose rate in three fractions, or 30 Gy low-dose rate; n=213). All investigators were masked to the assignment of treatment group. The primary endpoint was vaginal recurrence. The predefined non-inferiority margin was an absolute difference of 6% in vaginal recurrence. Analysis was by intention to treat, with competing risk methods. The study is registered, number ISRCTN16228756. FINDINGS: At median follow-up of 45 months (range 18-78), three vaginal recurrences had been diagnosed after VBT and four after EBRT. Estimated 5-year rates of vaginal recurrence were 1.8% (95% CI 0.6-5.9) for VBT and 1.6% (0.5-4.9) for EBRT (hazard ratio [HR] 0.78, 95% CI 0.17-3.49; p=0.74). 5-year rates of locoregional relapse (vaginal or pelvic recurrence, or both) were 5.1% (2.8-9.6) for VBT and 2.1% (0.8-5.8) for EBRT (HR 2.08, 0.71-6.09; p=0.17). 1.5% (0.5-4.5) versus 0.5% (0.1-3.4) of patients presented with isolated pelvic recurrence (HR 3.10, 0.32-29.9; p=0.30), and rates of distant metastases were similar (8.3% [5.1-13.4] vs 5.7% [3.3-9.9]; HR 1.32, 0.63-2.74; p=0.46). We recorded no differences in overall (84.8% [95% CI 79.3-90.3] vs 79.6% [71.2-88.0]; HR 1.17, 0.69-1.98; p=0.57) or disease-free survival (82.7% [76.9-88.6] vs 78.1% [69.7-86.5]; HR 1.09, 0.66-1.78; p=0.74). Rates of acute grade 1-2 gastrointestinal toxicity were significantly lower in the VBT group than in the EBRT group at completion of radiotherapy (12.6% [27/215] vs 53.8% [112/208]). INTERPRETATION: VBT is effective in ensuring vaginal control, with fewer gastrointestinal toxic effects than with EBRT. VBT should be the adjuvant treatment of choice for patients with endometrial carcinoma of high-intermediate risk. FUNDING: Dutch Cancer Society. Show less
BACKGROUND: After surgery for intermediate-risk endometrial carcinoma, the vagina is the most frequent site of recurrence. This study established whether vaginal brachytherapy (VBT) is as effective... Show moreBACKGROUND: After surgery for intermediate-risk endometrial carcinoma, the vagina is the most frequent site of recurrence. This study established whether vaginal brachytherapy (VBT) is as effective as pelvic external beam radiotherapy (EBRT) in prevention of vaginal recurrence, with fewer adverse effects and improved quality of life. METHODS: In this open-label, non-inferiority, randomised trial undertaken in 19 Dutch radiation oncology centres, 427 patients with stage I or IIA endometrial carcinoma with features of high-intermediate risk were randomly assigned by a computer-generated, biased coin minimisation procedure to pelvic EBRT (46 Gy in 23 fractions; n=214) or VBT (21 Gy high-dose rate in three fractions, or 30 Gy low-dose rate; n=213). All investigators were masked to the assignment of treatment group. The primary endpoint was vaginal recurrence. The predefined non-inferiority margin was an absolute difference of 6% in vaginal recurrence. Analysis was by intention to treat, with competing risk methods. The study is registered, number ISRCTN16228756. FINDINGS: At median follow-up of 45 months (range 18-78), three vaginal recurrences had been diagnosed after VBT and four after EBRT. Estimated 5-year rates of vaginal recurrence were 1.8% (95% CI 0.6-5.9) for VBT and 1.6% (0.5-4.9) for EBRT (hazard ratio [HR] 0.78, 95% CI 0.17-3.49; p=0.74). 5-year rates of locoregional relapse (vaginal or pelvic recurrence, or both) were 5.1% (2.8-9.6) for VBT and 2.1% (0.8-5.8) for EBRT (HR 2.08, 0.71-6.09; p=0.17). 1.5% (0.5-4.5) versus 0.5% (0.1-3.4) of patients presented with isolated pelvic recurrence (HR 3.10, 0.32-29.9; p=0.30), and rates of distant metastases were similar (8.3% [5.1-13.4] vs 5.7% [3.3-9.9]; HR 1.32, 0.63-2.74; p=0.46). We recorded no differences in overall (84.8% [95% CI 79.3-90.3] vs 79.6% [71.2-88.0]; HR 1.17, 0.69-1.98; p=0.57) or disease-free survival (82.7% [76.9-88.6] vs 78.1% [69.7-86.5]; HR 1.09, 0.66-1.78; p=0.74). Rates of acute grade 1-2 gastrointestinal toxicity were significantly lower in the VBT group than in the EBRT group at completion of radiotherapy (12.6% [27/215] vs 53.8% [112/208]). INTERPRETATION: VBT is effective in ensuring vaginal control, with fewer gastrointestinal toxic effects than with EBRT. VBT should be the adjuvant treatment of choice for patients with endometrial carcinoma of high-intermediate risk. FUNDING: Dutch Cancer Society. Show less
