The CancerWeb Report, What's New In Cancer: January, 1997
Breast Cancer

• Telomerase enzyme as a test for early breast cancer - We have discussed telomerase in a number of earlier issues of CancerWeb Report. This enzyme repairs and maintains the end segments of chromosomes, normally subject to a degenerative process somewhat like fraying, which finally prevents the cell from further division. Almost all normal adult cells lack this enzyme and have a limited lifespans, but cancer cells reacquire the activity and become in a sense immortal. Researchers at the M.D. Anderson Cancer Center in Houston found that most breast cancers had telomerase activity. However, most interesting was their report in the January, 1997 issue of Clinical Cancer Research, that 100% of early (Stage I) breast cancers had telomerase, as did 6 of 6 Stage 0 (so-called DCIS or ductal carcinomas in situ) tumor samples. There was no telomerase in samples of breast tissue adjacent to the tumors, and only one benign tumor had activity. Acquisition of telomerase activity must be a very early event in the development of breast cancer, and the very sensitive PCR repeat method test may be helpful in diagnosing early disease. (Bednarek, Clin Cancer Res 3:11, 1997)

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• c-Src protein expression, a potential new breast cancer marker - An article by researchers in Utrecht University Hospital in the Netherlands (in the December, 1996 issue of the Journal of Pathology) described overexpression of c-Src protein in breast cancer cells, accompanying a 4- to 30-fold increase of the c-Src tyrosine kinase activity. The actual function of c-Src in the cell is unknown. Normal breast tissue showed only traces of c-Src protein which was spread evenly throughout the cytoplasm rather than concentrated around the nucleus as in tumor cells. (Verbeek, J Pathol 180:383, 1996)

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• Induced abortion and the risk of breast cancer - In the December, 1996 issue of CancerWeb Report (Volume 2, Number 12, under Breast Cancer), we described the results of a Dutch case-control study which addressed the relationship to abortion in 918 women with breast cancer, and also looked at reporting bias by comparing regions of the Netherlands that differ in attitudes towards abortion. This, together with other studies from the US and Sweden, indicated that there was a reporting bias resulting from the fact that healthy controls are less likely than breast cancer patients to report on controversial, emotional issues like abortion, making the findings of studies based on interviews unreliable. Now comes a Danish study, based on that nation's National Registry of Induced Abortions including 370,715 abortions, the results of which appeared in the January 9, 1997 issue of the New England Journal of Medicine. This major study, independent of any reporting bias, found no overall effect of induced abortion on the risk of breast cancer, although there was a small increase in risk among the small number of women having the procedure done during their second trimester, and a lower than normal risk for those having abortions done before 7 weeks of pregnancy. (Melbye, New Engl J Med 336:81, 1997)

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• Oral contraceptives and breast cancer - The relationship between the use of oral contraceptives and breast cancer is unsettled. Studies done to determine whether there is a relationship have given conflicting results, and many of the larger ones have not shown a connection. It could be that amassing a large heterogeneous group of women may obscure a relationship affecting only a certain group. Indeed, more recent surveys such as the World Health Organization Collaborative Study, suggest that the effect of oral contraceptives may be restricted to younger women. A study from the Iceland Cancer Registry, reported in the January, 1997 issue of the British Journal of Cancer, specifically addressed this topic by focusing on the marked change in prescription practices that have occurred since 1960. Whereas only about 20% of women born before 1950 started using contraceptives after the age of 20, 82% of new users in Iceland are now well below 20. The researchers found that the risk of breast cancer was doubled with use of oral contraceptives for more than 4 years in those women born after 1950, rising to 3-fold after more than 8-years use. There was no significant increase in risk when women born in 1945-50 were included in the analysis together with those born between 1951 and 1967. The risk increased with duration in use only in women born after 1950, indicating that exposure at a young age is the critical factor, and emphasizing that studies of this association should distinguish groups on this basis. (Tryggvadottir, Br J Cancer 75:139, 1997)

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• Vitamins, fiber, and breast cancer, little or no connection? - A large study from the Netherlands, published in the January, 1997 issue of the British Journal of Cancer, has added to the recent crop of negative findings regarding an association of breast cancer and diet. Associations between fruit and vitamin C intake and reduced cancer incidence were weak and not statistically significant; the same was true of beta-carotene and vitamin C in those subjects with a high intake of polyunsaturates. This study of 62,573 women of whom 650 developed breast cancer over a 51-month period, concluded that there is no strong role, if any role at all, for vitamins C and E, beta-carotene, retinol, dietary fiber, vegetables, fruit or potatoes in the development of breast cancer. (Verhoeven, Br J Cancer 75:149, 1997)

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• What are the pain and other symptoms experienced by women after breast cancer surgery? - There have been a few studies addressing the issues of pain and other symptoms after breast cancer surgery, some reporting no difference between those undergoing modified radical mastectomy and conservative breast surgery, while others finding differences. A Finnish study, reported in the December, 1996 issue of the British Journal of Cancer, followed up for one year 93 patients treated during 1993-94. One year after treatment, 80% still had treatment-related symptoms in the scar area and nearly all had problems in the arm on the side of the operated breast. Surprisingly, post-treatment pain was more frequent after conservative surgery than after mastectomy, 33% versus 17%, and 23% versus 13%, for the breast and arm, respectively. Numbness was experienced by 75%, and swelling (edema) in over 30% after both forms of surgery. About 25% described phantom sensations' in the missing breast after mastectomy. Anxiety and depression scores were highest before surgery and decreased with time; they were significantly related to preoperative stressful events. (Tasmuth, Br J Cancer 74:2024, 1996)