Re: Screening has not reduced deaths from breast cancer, study shows
Evaluations of the effectiveness of mammographic screening on breast cancer mortality in England are confounded by changes in hormone use.1,2 Since 1962 large increases in breast cancer different age groups have matched increases in hormone use (Fig 1). There have been falls in hormone use in the 1970s, mid 1990s, and, in the 2000s when the Women’s Health Institute randomised controlled trial confirmed HRT increased breast cancers and breast cancer mortality. Breast cancers increased within one year of use while use for more than 5 years trebled the risk in both the WHI and MWS.
In 2007 the International Agency for Cancer Research of the World Health Organization classified progestogen/oestrogen oral contraceptives as Group 1 carcinogens.2 Reductions in hormone use matched reductions in breast cancer incidences and mortality. 3,4
Many studies found that longer progestogen exposure before a first full time pregnancy is a high risk factors for breast cancer. Promotion of long-acting hormonal contraceptives to teenagers has been accompanied by increases in invasive breast cancer in younger women. In the United States, the incidence of metastatic stage IV breast cancer increased by 78% in women aged 25 to 39 from 1976 to 2009 (34 years). For this age group the national 5-year survival was 31% and the 10-year overall survival below 20%.5
1 Mukhtar T, Yeates D, Goldacre M. Breast cancer mortality trends in England and the assessment of the effectiveness of mammography screening: population-based study. J R Soc Med 2013:106:234-42.
2 IARC. Combined estrogen-progestogen contraceptives and combined estrogen-progestogen menopausal therapy. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans 2007; Volume 91
3 Grant ECG. Fall in HRT use would have reduced breast cancer mortality. BMJ (Published 28 January 2005)
4 Colditz GA. Decline in breast cancer incidence due to removal of promoter: combination estrogen plus progestin. Breast Cancer Res. 2007;9:108.
5 Johnson RH, Chein FL, Bleyer A. Incidence of breast cancer with distant involvement among women in the United States, 1976 to 2009. JAMA 2013;309(8):800-805
Competing interests: No competing interests