© 2004 by Oxford University Press
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© 2004 Oxford University Press
CORRESPONDENCE |
Re: Trends in the Treatment of Ductal Carcinoma In Situ of the Breast
Correspondence to: Peter C. Gøtzsche, MD, DrMedSci, MSc, The Nordic Cochrane Centre, Rigshospitalet, Dept. 7112, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark (e-mail: pcg{at}cochrane.dk)
Baxter et al. (1) report that about half the women undergoing lumpectomy for ductal carcinoma in situ do not get radiotherapy. The authors consider this to be undertreatment, because several studies have shown that radiotherapy reduces the risk of local recurrence and of invasive cancer. But the effect on mortality is not encouraging (2), and I believe the 50–50 split reflects the considerable uncertainty about what to do with carcinoma in situ.
What the authors found most likely represents overtreatment. More than anything else, people with cancer want to increase their chance of survival. Radiotherapy causes adverse cardiovascular effects, and in a large meta-analysis, it was predicted that radiotherapy treatment of women at low risk, such as those who have their cancers identified at screening, will increase overall mortality (2).
Women with carcinoma in situ are at exceptionally low risk of dying from breast cancer, and it is therefore very likely that radiotherapy will increase overall mortality by even more than predicted in the meta-analysis. Tumor recurrence is sometimes used as a surrogate marker for mortality in cancer trials, but it is obviously a very misleading marker in this case. The studies on tumor recurrence that Baxter et al. cite do not have sufficient power to address overall mortality because very few women died. The best evidence we have is, therefore, the meta-analysis, which makes me seriously question the wisdom of treating women with carcinoma in situ with radiotherapy rather than using a wait-and-see approach.
There is also substantial surgical overtreatment because practically all patients were treated surgically; in 1999, 28% of women got a mastectomy (1), despite the fact that less than half of these cell changes ever develop into cancer.
Not only the treatment but also the diagnosis of carcinoma in situ seems out of control. It is detected by mammography, but although breast cancer is very rare among women 18–39 years of age and mammography screening is not recommended, 4.8% of the cases of carcinoma in situ were found in this age group (1). Furthermore, 18.0% of the cases were found in women aged 70–79 years, and 5.7% of the cases were found in women aged 80 years and older. These age groups are generally not screened in Europe because we doubt whether the possible benefits outweigh the harms. In fact, because screening leads to about 30% overdiagnosis and overtreatment, even for invasive cancers (3), this doubt can be raised for any age group. For example, the group that did a meta-analysis for the U.S. Preventive Services Task Force expressed concern whether, across all age groups, the magnitude of benefit is sufficient to outweigh the harms (4).
It seems to me that the harms of screening for cancer need to be much better understood, acknowledged, and honestly communicated, both in scientific papers and in the information materials directed to women, which currently are very misleading (5–7).
REFERENCES
1 Baxter NN, Virnig BA, Durham SB, Tuttle TM. Trends in the treatment of ductal carcinoma in situ of the breast. J Natl Cancer Inst 2004;96:443–8.
2 Early Breast Cancer Trialists‘ Collaborative Group. Favourable and unfavourable effects on long-term survival of radiotherapy for early breast cancer: an overview of the randomised trials. Lancet 2000;355:1757–70.[CrossRef][ISI][Medline]
3 Gotzsche PC. On the benefits and harms of screening for breast cancer. Int J Epidemiol 2004;33:56–64.
4 Humphrey LL, Helfand M, Chan BK, Woolf SH. Breast cancer screening: a summary of the evidence for the U.S. Preventive Services Task Force. Ann Intern Med 2002;137(5 Part 1):347–60.
5 Welch HG. Should I be tested for cancer? Maybe not and here's why. Berkeley (CA): University of California Press; 2004.
6 Thornton H, Edwards A, Baum M. Women need better information about routine mammography. BMJ 2003;327:101–3.
7 Jorgensen KJ, Gotzsche PC. Presentation on websites of possible benefits and harms from screening for breast cancer: cross sectional study. BMJ 2004;328:148–51.
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J Natl Cancer Inst 2004 96: 1258.
J Natl Cancer Inst 2004 96: 1258-1259.
J Natl Cancer Inst 2004 96: 1259-1260.
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