Screening has not reduced deaths from breast cancer, study showsBMJ 2013; 346 doi: https://doi.org/10.1136/bmj.f3780 (Published 11 June 2013) Cite this as: BMJ 2013;346:f3780
All rapid responses
All that Brewster et al(1)say may be true. But do not they think at this juncture in the history of breast screening that it would have been decent for screeners to tell me, when they invited me to be screened, that screening is conducted on faith not evidence of benefit? Rather than misleading me to believe that I was more likely to die of breast cancer without screening, which claim they must agree is not and never has been warranted by the evidence.
That comparison of mortality trends is not an ideal way to show an effect of an intervention does not mean that it is okay to proceed with the intervention whistling in the dark in the absence of evidence of benefit. For 25 years. In the face of overwhelming harm, evidence of which is apparent to the naked eye.
Do they not think it would have been decent for my doctors to ensure that when receiving a diagnosis through screening I understood that this cannot mean that I “had cancer”, since a disputed but large proportion of screening diagnoses are clinically inconsequential, while the majority will not benefit from earlier detection and it is simply not known if any do. That at best they can be few, 1 in 15 according to their estimate, which Professor Marmot himself has admitted is uncertain. So that it would be better to use this figure by way of illustration to educate women about what screening means than as an accurate representation of any diagnosed woman’s actual probability of benefitting from the treatment she will at that point be too frightened to decline. And too preoccupied with current danger to be able to ask the obvious question, “Why didn’t you tell me this before you screened me?”
Why are they still defending screening in the face of insufficient evidence when, given what they know, they should be bending their efforts towards making sure every woman invited for screening understands the big risk of grave harm and the lack of evidence of chance of benefit?
More than half a year has passed since the review panel added its evaluation of screening to the existing range. While it is misleading to cherry pick this estimate to inform women rather than explaining the impossibility, given the nature of the evidence, of getting accurate figures, and therefore of being able to assure them that they have a chance of benefit, what is incomprehensible is the absence of any sign of urgency in informing women at all.
Another million women have been screened since then. 8000 encouraged to believe misleadingly they ‘have cancer’; about 5,350 will receive no benefit from earlier treatment; an optimistic 650 may die of something other than breast cancer though whether any live longer is unclear; 2000 didn’t ‘have cancer’. Nobody knows which is which. Yet they believe falsely ‘screening saved my life’, and these writers are letting this debacle continue while quibbling about studies.
(1)AGE-RELATED DIFFERENCES IN USE OF TREATMENT MEAN THAT IT IS NOT APPROPRIATE TO JUDGE THE EFFECTIVENESS OF MAMMOGRAPHIC SCREENING BY COMPARING BREAST CANCER MORTALITY TRENDS IN SCREENING AND NON-SCREENING AGE GROUPS David H Brewster, Director, Scottish Cancer Registry Lesley A Bhatti, Catherine S Thomson, David A Cameron, John A Dewar
BMJ 2013; 346:f3780
Competing interests: Diagnosed through screening
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
AGE-RELATED DIFFERENCES IN USE OF TREATMENT MEAN THAT IT IS NOT APPROPRIATE TO JUDGE THE EFFECTIVENESS OF MAMMOGRAPHIC SCREENING BY COMPARING BREAST CANCER MORTALITY TRENDS IN SCREENING AND NON-SCREENING AGE GROUPS
At least three papers have now used comparisons of secular trends in age-specific mortality rates of breast cancer to make inferences about the effectiveness of mammographic screening for breast cancer.[1-3] However, Autier and colleagues were circumspect in their interpretation, acknowledging that "the particularly larger reduction in mortality in women <50 years old may reflect better targeting of effective treatments and response to treatments".
Previous research suggests that the relative effects of adjuvant chemotherapy and hormone therapy do not vary substantially by age. However, there is evidence that older women are less likely to undergo some modalities of treatment for breast cancer.[6,7]
We have analysed Scottish Cancer Registry (SCR) data to investigate the use of surgery, radiotherapy, chemotherapy, and hormone therapy by age group in women diagnosed with invasive breast cancer between 1997 and 2011. Treatment data are recorded at the time of completion of a cancer registration, and thus it is possible that some treatments, delayed by neo-adjuvant therapy, may go unrecorded. For this reason, we supplemented the SCR data with information on surgery, radiotherapy, and chemotherapy held on linked hospital discharge records up to one month before or 12 months after the recorded date of incidence. ‘Biological therapies’, such as trastuzumab, used to be recorded as chemotherapy on SCR, but latterly have been recorded under a free-text field for ‘other therapy’. For the purposes of this analysis, we re-assigned biological therapies to the chemotherapy category.
The percentage use of each major treatment modality by age group is shown in the figure. It is apparent that the use of different therapies (in particular, chemotherapy) varies substantially by age, with higher use of all major therapies except hormonal therapy among younger age groups. The overall pattern was similar in three consecutive periods of diagnosis: 1997-2001, 2002-2006, and 2007-2011 (data not shown, but available on request).
Previous research suggests that SCR data are reasonably complete, both in terms of overall ascertainment and in terms of the recording of treatment information. Although we supplemented the SCR treatment data using linked hospital discharge records, this made only a marginal difference to treatment levels (absolute difference 2.5% or less for the total period of observation, depending on treatment modality).
Our analysis confirms the perception, and the findings of previous research,[6,7] that there are striking age-related differences in use of breast cancer therapy. Therefore, we conclude that it is not appropriate to judge the effectiveness of mammographic screening by comparing breast cancer mortality trends in screening and non-screening age groups in observational studies of the general population.
1. Jørgensen KJ, Zahl PH, Gøtzsche PC. Breast cancer mortality in organised mammography screening in Denmark: comparative study. BMJ 2010;340:c1241
2. Autier P, Boniol M, La Vecchia C, Vatten L, Gavin A, Héry C, Heanue M. Disparities in breast cancer mortality trends between 30 European countries: retrospective trend analysis of WHO mortality database. BMJ 2010;341:c3620
3. 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.
4. Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). Comparisons between different polychemotherapy regimens for early breast cancer: meta-analyses of long-term outcome among 100 000 women in 123 randomised trials. Lancet 2012;379:432–44.
5. Early Breast Cancer Trialists’ Collaborative Group (EBCTCG). Relevance of breast cancer hormone receptors and other factors to the efficacy of adjuvant tamoxifen: patient-level meta-analysis of randomised trials. Lancet 2011;378:771–84.
6. Lavelle K, Todd C, Moran A, Howell A, Bundred N, Campbell M. Non-standard management of breast cancer increases with age in the UK: a population based cohort of women ≥65 years. Br J Cancer 2007;96:1197-203.
7. Lavelle K, Moran A, Howell A, Bundred N, Campbell M, Todd C. Older women with operable breast cancer are less likely to have surgery. Br J Surg 2007;94:1209-15.
8. Brewster DH, Stockton DL. Ascertainment of breast cancer by the Scottish Cancer Registry: An assessment based on comparison with five independent breast cancer trials databases. Breast 2008;17:106-8.
9. Brewster DH, Stockton D, Harvey J, Mackay M. Reliability of cancer registration data in Scotland, 1997. Eur J Cancer 2002;38:414-7.
Competing interests: DAC and JAD were members of the Independent UK Panel on Breast Cancer Screening