To The New Zealand Press Association:

This is to express my support for including women from age 40 into regular, high quality, organized screening for breast cancer. Those who would dogmatically exclude women from the benefit of this proven life-saving method, do not fully understand the biology of this disease, and cite randomized trials that have been initiated before sufficient knowledge has accumulated about the natural history of this disease and therefore have been carried out with interscreening intervals which are too long.

The basic issue is that the growth rate of the different breast cancer subtypes have equally short preclinical detectable phase (so-called sojourn time, i.e. the time-difference between mammographic detectibility and clinical detectibility) in premenopausal women, while there is a considerable spread in the length of this preclinical detectable phase according to tumor type among postmenopausal women. Also, it is fundamental to take the propensity of worsening of the histologic grade into account (the so-called phenotypic drift, i.e. the propensity for a less aggressive tumor to become more aggressive during tumor growth).

According to our research 8 breast cancers out of 10 (81%) have the potential for dedifferentiation (worsening of malignancy grade during tumor growth) in age group 40-54, while this figure is one out of two (about 50%) in women aged 55 and older. This clearly tells us that more breast cancers benefit from early detection in "younger women"...leading to the conclusion that "If anybody is to be screened, it should be the younger women"!

The recommendation of the Swedish government is that screening should begin from age 40 and above.


I have been screening age group 40-49 for 26 yrs now - and will continue to do so.

The American Cancer Society clearly recommends screening for women aged 40 and above. Their new guidelines are available at:

The randomized controlled trials clearly underestimate the benefit of screening, and it is very difficult for the individual woman to "translate" the "general to the specific". To answer the question: “What will be my personal benefit if I attend regular screening?” In order to answer this question more clearly, we have published new data in The Lancet. The Abstract of our publication is included below.


László Tabár, M.D.

Professor of Radiology

University of Uppsala, Uppsala, Sweden

Chairman, Department of Mammography

Falun Central Hospital, Falun, Sweden

Lancet. 2003 Apr 26;361(9367):1405-10. 

Mammography service screening and mortality in breast cancer patients: 20-year follow-up before and after introduction of screening.

Tabar L, Yen MF, Vitak B, Chen HH, Smith RA, Duffy SW.

Department of Mammography, Central Hospital, Falun, Sweden.

BACKGROUND: The long term effect of mammographic service screening is not well established. We aimed to assess the long-term effect of mammographic screening on death from breast cancer, taking into account potential biases from self-selection, changes in breast cancer incidence, and classification of cause of death. METHODS: We compared deaths from breast cancer diagnosed in the 20 years before screening was introduced (1958-77) with those from breast cancer diagnosed in the 20 years after the introduction of screening (1978-97) in two Swedish counties, in 210000 women aged 20-69 years. We also compared deaths from all cancers and from all causes in patients diagnosed with breast cancer in the 20 years before and after screening was introduced. In the analysis, data were stratified into age-groups invited for screening (40-69 years) and not invited (20-39 years), and by whether or not the women had actually received screening. We also analysed mortality for the 40-49-year age-group separately. FINDINGS: The unadjusted risk of death from breast cancer dropped significantly in the second screening period compared with the first in women aged 40-69 years (relative risk [RR] 0.77 [95% CI 0.7-0.85]; p<0.0001). No such decline was seen in 20-39 year olds. After adjustment for age, self-selection bias, and changes in breast-cancer incidence in the 40-69 years age-group, breast-cancer mortality was reduced in women who were screened (0.56; 0.49-0.64 p<0.0001), in those who were not screened (0.84 [0.71-0.99]; p=0.03), and in screened and unscreened women combined (0.59 [0.53-0.66]; p<0.0001). After adjustment for age, self-selection bias, and changes in incidence in the 40-49-year age-group, deaths from breast cancer fell significantly in those who were screened (0.52 [0.4-0.67]; p<0.0001); and in all women, screened and unscreened combined (0.55 [0.44-0.7] p<0.0001) but not in unscreened women (p=0.2). In both 40-69-year and 40-49-year age-groups, reductions in deaths from all cancers and from all-causes in women with breast cancer were consistent with these results. INTERPRETATION: Taking account of potential biases, changes in clinical practice and changes in the incidence of breast cancer, mammography screening is contributing to substantial reductions in breast cancer mortality in these two Swedish counties.