Observational research suggests that antioxidant vitamins may prevent cancer, but findings from randomised trials are mostly negative. Three recent studies have revisited this topic. The first trial, of 35,533 relatively healthy men aged 50 years or older, showed that selenium or vitamin E, alone or in combination, did not prevent prostate cancer. The second trial involved 14,641 male physicians aged 50 years or older, with a mean follow-up of eight years; it found that neither vitamin E nor vitamin C supplementation reduced prostate or total cancer risk. The third trial involved 7,627 women free of cancer at baseline, followed up for an average 9.4 years. Again, supplementation with vitamin C, vitamin E or beta carotene offered no benefit in terms of cancer incidence or mortality.(Lippman SM, Klein EA, Goodman PJ et al. JAMA 2009;301:39-51; Gaziano JM, Glynn RJ, Christen WG et al. JAMA 2009;301:52-62; Lin J, Cook NR, Albert C et al. J Natl Cancer Inst 2009;101(1):14-23)
US researchers have carried out a trial to determine whether risedronate prevents bone loss in premenopausal women having chemotherapy for breast cancer. In the study, 216 women were treated with oral calcium 600mg and vitamin D 400IU daily and randomly assigned to oral risedronate 35mg weekly or placebo. Risedronate was well tolerated, but there was no difference between treatment and placebo with respect to the mean change or percentage change in lumbar spine BMD (risedronate arm, 4.3 per cent loss; placebo arm, 5.4 per cent loss, at one year). (Hines SL, Mincey BA, Sloan JA et al. J Clin Oncol 2008; doi: 10.1200/JCO.2008.191783)
Debate continues on fertility drugs and women's risk of cancer. In a population-based cohort study of 54,362 women with infertility problems, researchers from Denmark assessed the effects of four groups of fertility drugs over an average 16 years. They found no overall increased risk for ovarian cancer after use of any fertility drug, even among women who had undergone 10 or more cycles of treatment. A population-based study of 15,030 women in Israel found those who had used drugs to induce ovulation had a 36 per cent increased risk of cancer at any site. The risk of uterine cancer rose more than threefold. However, there was no association between use of ovulation-inducing agents and ovarian cancer. (Jensen A, Sharif H, Frederiksen K, Kruger Kjaer S. BMJ 2009; 338:b249;doi:10.1136/bmj.b249.)
Calderon-Margalit R, Friedlander Y, Yanetz R et al. Am J Epidemiol 2009; 169(3): 365-75
Tadpoles could prove crucial in the development of effective drugs for the treatment of skin cancer, according to a UK study. Researchers at the University of East Anglia have identified a compound which, when introduced into Xenopus laevis tadpoles, blocks the movement of melanophores that give the tadpoles their distinctive markings and adult frogs their greenish-brown colouring. Uncontrolled movement and growth of melanophores in tadpoles and humans causes skin cancer, so it is thought that blocking the migration of these cells could prevent this. The researchers aim to test their novel inhibitor in other species. (Tomlinson ML, Guan P, Morris RJ et al. Chem Biol 2009;16(1):93-104)
Originally published in the March 2009 edition of MIMS Oncology & Palliative Care.