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phyto-oestrogens do. Like phyto-oestrogens, tamoxifen has mild —_ These findings would later be challenged. oestrogenic properties but is considered an anti-oestrogen since it Tamoxifen is now recommended for all premenopausal women inhibits the activity of regular oestrogens. More accurately, with hormone-positive cancers, as well as for most post- tamoxifen is an oestrogen-blocker. It fights breast cancer by com- menopausal women with breast cancer and/or a growing number peting with oestrogen for space on oestrogen receptors in the of women with hormone-negative cancers. Tamoxifen is current- tumour tissue. Every tamoxifen molecule that hooks onto an ly used by more women with breast cancer than any other drug.® oestrogen receptor prevents an oestrogen molecule from linking Tamoxifen (brand name Nolvadex) is now the most widely pre- up at the same site. Without a steady supply of oestrogen, cells in scribed cancer medication in the world. It generated revenues of an oestrogen-receptor-positive (ER+) tumour do not thrive and the US$265 million in 1992. By 1995, worldwide sales of Nolvadex tumour's ability to spread is reduced.* reached $400 million.” And at AUD$90 for one month's supply, it However, tamoxifen exhibited two conflicting characteristics. doesn't come cheap (the Australian Pharmaceutical Benefits It could act either as an anti-oestrogen or as an oestrogen. Scheme covers $70). Therefore, while tamoxifen is anti-oestrogenic to the breast, it Tamoxifen was developed by UK-based Imperial Chemical also acts as an oestrogen to the uterus and, to a lesser extent, the Industries (ICI), one of the world's largest multinational chemical heart, blood vessels and bone. So, although it initially showed the corporations. Zeneca, an ICI subsidiary, is responsible for manu- tendency to counter breast cancer facturing and marketing the hormone recurrence, it would soon be revealed and is now the world's largest can- that it also promoted particularly cer-drug company. aggressive uterine and liver cancers, Like phyto-oestrogens, tamoxifen It is no surprise that ICI's profits caused fatal blood clots and interfered has mild oestrogenic properties come from playing both sides of the with many other functions. cancer industry. ICI's agrochemical Doctors, however, were quick to but is considered an anti- division, which includes Zeneca, jump on the tamoxifen bandwagon, oestrogen since it inhibits the manufactures chlorinated and other turning a blind eye to its more injuri- industrial chemicals including her- ous tendencies. Starting in the 1970s activity of regular oestrogens. bicides. All are poisonous, and oncologists began using tamoxifen to More accurately, tamoxifen is many are known endocrine-disrup- treat women with cancer, often in com- Y tors that have been incriminated as bination with other drugs, radiation or an oestrogen-blocker. causes of breast cancer. ICI's prof- surgery such as lumpectomy and mas- its swell by manufacturing chemi- tectomy, with modest success. Like cals that on the one hand cause DES, tamoxifen's benefits were then breast cancer, and on the other hand extended for use as a preventive against osteoporosis and heart reputedly cure breast cancer. disease. Today, doctors are treating about one million American breast — LIMITED BENEFITS OF TAMOXIFEN cancer patients with tamoxifen, about 20 per cent of them for Tamoxifen 's benefits are determined by several factors:* more than five years. As studies published in the New England * Postmenopausal women who are ER-positive (have a positive Journal of Medicine in 1989 and the Journal of the National oestrogen receptor status) get the most benefit. Cancer Institute in 1992 showed, women with breast cancer who For postmenopausal women who are ER-negative, the benefits took tamoxifen reduced their chances of developing cancer in the appear to outweigh the risks. other breast (counterlateral cancer) by about 30 to 50 per cent.* ¢ For premenopausal women who are ER-pi call Datantial hana oestrogen since it inhibits the activity of regular oestrogens. More accurately, tamoxifen is an oestrogen-blocker. LIMITED BENEFITS OF TAMOXIFEN Tamoxifen 's benefits are determined by several factors:* * Postmenopausal women who are ER-positive (have a positive oestrogen receptor status) get the most benefit. + For postmenopausal women who are ER-negative, the benefits appear to outweigh the risks. ¢ For premenopausal women who are ER-positive, it's a tough call. Potential benefits are small. « Premenopausal women who are ER- negative receive virtually no benefit. * Tamoxifen is more effective in women who have cancer in their lymph nodes than in those whose nodes are cancer-free. In 1992 the Lancet published a review of a number of studies in which a total of 30,000 breast cancer patients were ran- domly assigned either to take tamoxifen or not. The average patient in this collabora- tive study was followed up for between five and six years. Of the patients taking tamoxifen, 74.4 per cent survived, as com- pared with 70.9 per cent in the non-tamox- ifen group—a_less-than-impressive improvement. The report found that the group helped _—— most consisted of postmenopausal women with ER-positive status. The study went on to report that premenopausal women who are ER-negative had absolutely no benefit from taking tamoxifen.’ YE) J ZELLIL Vee anaes Ny fel) @BOxash 44 - NEXUS JUNE - JULY 1998 reputedly cure breast cancer.