Overview of the main outcomes in breast-cancer prevention trials
ABSTRACT Early findings on the use of tamoxifen or raloxifene as prophylaxis against breast cancer have been mixed; we update available data and overview the combined results.
All five randomised prevention trials comparing tamoxifen or raloxifene with placebo were included. Relevant data on contralateral breast tumours and side-effects were included from an overview of adjuvant trials of tamoxifen versus control.
The tamoxifen prevention trials showed a 38% (95% CI 28-46; p<0.0001) reduction in breast-cancer incidence. There was no effect for breast cancers negative for oestrogen receptor (ER; hazard ratio 1.22 [0.89-1.67]; p=0.21), but ER-positive cancers were decreased by 48% (36-58; p<0.0001) in the tamoxifen prevention trials. Age had no apparent effect. Rates of endometrial cancer were increased in all tamoxifen prevention trials (consensus relative risk 2.4 [1.5-4.0]; p=0.0005) and the adjuvant trials (relative risk 3.4 [1.8-6.4]; p=0.0002); no increase has been seen so far with raloxifene. Venous thromboembolic events were increased in all tamoxifen studies (relative risk 1.9 [1.4-2.6] in the prevention trials; p<0.0001) and with raloxifene. Overall, there was no effect on non-breast-cancer mortality; the only cause showing a mortality increase was pulmonary embolism (six vs two).
The evidence now clearly shows that tamoxifen can reduce the risk of ER-positive breast cancer. New approaches are needed to prevent ER-negative breast cancer and to reduce the side-effects of tamoxifen. Newer agents such as raloxifene and the aromatase inhibitors need to be evaluated. Although tamoxifen cannot yet be recommended as a preventive agent (except possibly in women at very high risk with a low risk of side-effects), continued follow-up of the current trials is essential for identification of a subgroup of high-risk, healthy women for whom the risk-benefit ratio is sufficiently positive.
SourceAvailable from: Ivana Sestak[Show abstract] [Hide abstract]
ABSTRACT: Tamoxifen has been shown to reduce the risk of developing estrogen receptor (ER)-positive breast cancer by at least 50%, in both pre- and postmenopausal women. The current challenge is to find new agents with fewer side effects and to find agents that are specifically suitable for premenopausal women with ER-negative breast cancer. Other selective estrogen receptor modulators (SERMs), such as raloxifene, arzoxifene, and lasofoxifene, have been shown to reduce the incidence of breast cancer by 50%-80%. SERMs are interesting agents for the prevention of breast cancer, but longer follow-up is needed for some of them for a complete risk-benefit profile of these drugs. Aromatase inhibitors have emerged as new drugs in the prevention setting for postmenopausal women. In the Mammary Prevention 3 (MAP3) trial, a 65% reduction in invasive breast cancer with exemestane was observed, and the Breast Cancer Intervention Study-II trial, which compared anastrozole with placebo, reported a 60% reduction in those cancers. Although SERMs and aromatase inhibitors have been proven to be excellent agents in the preventive setting specifically for postmenopausal women and ER-positive breast cancer, newer agents have to be found specifically for ER-negative breast cancers, which mostly occur in premenopausal women.Cancer Management and Research 01/2014; 6:423-30. DOI:10.2147/CMAR.S55219
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ABSTRACT: The pattern of double primary cancer after treatment for breast cancer is important for patient survival. We analyzed 108 cases of metachronous double primary cancer in breast cancer patients treated from 1999 to 2012. Metachronous double primary cancers occurred in 108 of 2,657 patients (4.1%) with breast cancer. The median time to the occurrence of second cancer after diagnosis of the first was 58.4±41.2 months (range, 6.9 to 180.2 months). The most common cancer was thyroid cancer, which occurred in 45 patients (41.7%). This was followed by gastric cancer in 16 patients (14.8%), endometrial cancer in 10 patients (9.3%), and cervical cancer in seven patients (6.5%). The relative risk showed a significant increase in endometrial (4.78; 95% confidence interval [CI], 1.66 to 13.79), gastric (2.61; 95% CI, 1.68 to 4.06), and thyroid cancer (1.95; 95% CI, 1.37 to 2.79). At 5 years after diagnosis of breast cancer, secondary cancer occurred in 48 patients (44.4%), with 50.0% of the endometrial, 56.3% of the stomach, and 37.8% of the thyroid cancer cases being diagnosed after 5 years. Median survival after diagnosis of the second cancer was 123.9±11.2 months. The prognosis was mainly influenced by the anatomic site. The incidence of endometrial, stomach, and thyroid cancer increased significantly after treatment with primary breast cancer, and survival was dependent on early detection and the type of second primary cancer. A prolonged follow-up examination for metachronous double primary cancer is needed to provide early detection and improve survival time in patients with breast cancer.Cancer Research and Treatment 10/2014; 47(1). DOI:10.4143/crt.2013.215 · 2.98 Impact Factor
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ABSTRACT: The increased practice of traditional Chinese medicine worldwide has raised concerns regarding herb-drug interactions. We analyzed the usage of Chinese herbal products containing dang-qui and investigated whether dang-qui therapy increases endometrial cancer risk among tamoxifen-treated breast cancer survivors in Taiwan. All patients newly diagnosed with invasive breast cancer who received tamoxifen treatment from January 1, 1998, to December 31, 2008 were selected from the National Health Insurance Research Database. The usage, frequency of service and type of Chinese herbal products containing dang-qui prescribed across the 31,970 survivors were evaluated. Logistic regression method was employed to estimate the odds ratios for utilization of Chinese herbal products containing dang-qui. Cox proportional hazard regression was performed to calculate the hazard ratio of endometrial cancer associated with dang-qui use within the cohort. Almost one in two study subjects had used dang-qui. Among 31,938 tamoxifen-treated breast cancer survivors, 157 cases of subsequent endometrial cancer were identified. The hazard ratio for development of endometrial cancer among breast cancer survivors aged 20-79 years who had taken dang-qui after tamoxifen treatment was decreased compared to survivors who had never used dang-qui (HR: 0.61, 95%CI: 0.44-0.84). To minimise potential confounding factors, women with breast cancer in the reproductive age were excluded from further analysis, and the negative relationship between dang-qui consumption and subsequent endometrial cancer among breast cancer survivors aged 55-79 years was still observed, although not significantly (HR: 0.74, 95%CI: 0.46-1.17). Dang-qui consumption is common among breast cancer survivors aged 20-79 years and seems decrease the risk of subsequent endometrial cancer after less than a cumulative dose of 7,500 mg of tamoxifen treatment.PLoS ONE 12/2014; 9(12):e113887. DOI:10.1371/journal.pone.0113887 · 3.53 Impact Factor