Breast cancer risk: weaving facts into fabric

Synergistic anticancer effects of combined γ-tocotrienol with statin or receptor tyrosine kinase inhibitor treatment

Systemic chemotherapy is the only current method of treatment that provides some chance for long-term survival in patients with advanced or metastatic cancer. γ-Tocotrienol is a natural form of vitamin E found in high concentrations in palm oil and displays potent anticancer effects, but limited absorption and transport of by the body has made it difficult to obtain and sustain therapeutic levels in the blood and target tissues. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase and are an example of a promising cancer chemotherapeutic agent whose clinical usefulness has been limited due to high-dose toxicity. Similarly, erlotinib and gefitinib are anticancer agents that inhibit the activation of individual HER/ErbB receptor subtypes, but have shown limited clinical success because of heterodimerization between different EGF receptor family members that can rescue cancer cells from agents directed against a single receptor subtype. Recent studies have investigated the anticancer effectiveness of low-dose treatment of various statins or EGF receptor inhibitors alone and in combination with γ-tocotrienol on highly malignant +SA mouse mammary epithelial cells in vitro. Combined treatment with subeffective doses of γ-tocotrienol with these other chemotherapeutic agents resulted in a synergistic inhibition of +SA cell growth and viability. These findings strongly suggest that combined treatment of γ-tocotrienol with other anticancer agents may not only provide an enhanced therapeutic response but also provide a means to avoid the toxicity, low bioavailability, or limited therapeutic action associated with high-dose monotherapy.

Should Tamoxifen Be Used in Breast Cancer Prevention?

Breast cancer is the most commonly diagnosed cancer in women. The risk of developing breast cancer can be lowered by maintaining a healthy bodyweight and avoiding long-term use of combined estrogen and progestogen replacement after menopause. However, many women are at an increased risk of developing breast cancer secondary to age, early menarche, a family history of breast cancer or a personal history of benign breast disease. These women may now be offered tamoxifen as a chemoprevention therapy. Five years of tamoxifen treatment results in a reduction in the relative risk of developing estrogen receptor-positive breast cancer of 48%. This benefit outweighs the risk of tamoxifen-related adverse events for many healthy women. However, the benefit-risk ratio of tamoxifen chemoprevention varies for individual women. The randomized clinical trials evaluating standard-dose tamoxifen versus placebo as chemoprevention therapy are reviewed and analyzed to determine which particular women are most likely to benefit and least likely to experience a tamoxifen-related adverse event. Tamoxifen decreases the risk of breast cancer associated with aging, having a first-degree relative with disease, and a personal diagnosis of atypical ductal hyperplasia or lobular carcinoma in situ. Women who have had a hysterectomy and are at low risk of a thromboembolic event have a decreased risk of adverse effects associated with tamoxifen therapy. The strengths and weaknesses of the Gail model (frequently used to assess an individual's risk of developing invasive breast cancer over the next 5 years) are highlighted. A method for assessing the benefit-risk ratio for an individual woman is presented. Alternative breast cancer chemoprevention strategies are considered, including the use of aromatase inhibitors. This article discusses the pros and cons of these various preventive therapies and concludes that at this time, tamoxifen remains the gold standard for breast cancer prevention.