CORRESPONDENCE

Re: Breast-Conserving Surgery With or Without Radiotherapy: Pooled-Analysis for Risks of Ipsilateral Breast Tumor Recurrence and Mortality

Claire Verschraegen, Vincent Vinh-Hung

Affiliations of authors: University of New Mexico, Cancer Research and Treatment Center, Albuquerque (CV); Oncology Center, AZ-VUB, Brussels, Belgium (VVH)

Correspondence to: Claire Verschraegen, MD, University of New Mexico, Cancer Research and Treatment Center, 900 Camino de Salud, Albu-querque, NM 87131 (e-mail: cverschraegen{at}salud.unm.edu)

We recently received an e-mail from Dr. Seymour Levitt (Department of Radiation Oncology, Fairview University Hospital, University of Minnesota, Minneapolis) about our paper (1) that drew our attention to the results of a Bayesian analysis of the impact of radiation on early breast cancer that he and his colleagues had performed in 1996 (2) and which was absent from the references of our paper.

Our focus was on standard methods of meta-analysis; currently, Bayesian methods are not part of mainstream meta-analyses. A recent systematic overview of radiotherapy in breast cancer performed by a Swedish team identified no other Bayesian-based paper (3). Furthermore, there is no public-domain dedicated Bayesian meta-analysis software; by contrast, stand-alone software for meta-analyses by classic methods are readily available (4,5). Software routines for Bayesian analysis implemented in packages such as S-Plus or BUGS do exist, but they have a steep learning curve, which necessitates additional time, cost, and manpower that unfunded studies cannot afford.

Was the omission of the analysis by Levitt et al. (2) a shortcoming of our meta-analysis? Bloom et al. (6) compared the results of meta-analyses performed according to classic or Bayesian methods and noted a considerable lack of agreement and important divergence of results. However, Bloom et al. also noted that one might gain confidence that a result is correct if the same answer is obtained by using two different methods (6). Using a Bayesian method, Levitt et al. (2) estimated that an 87% probability of a positive survival benefit at 10 years was associated with the addition of radiation to lumpectomy in patients with negative lymph nodes and clear surgical margins, a result that clearly indicates a survival advantage associated with radiotherapy. Using classic statistical methods, we obtained a similar result (1). The fact that these two analytic methods produced comparable results, even when the analyses were separated by 8 years, argues not only that the result is robust but also that Bayesian analysis can be an extremely valuable tool that should perhaps be an integral part of meta-analyses. We gratefully acknowledge Dr. Levitt for drawing attention to our omission.

NOTES

The text of this letter was approved by Dr. Seymour Levitt and by the members of the mailing list [onco] contributing to the Breast-Conserving Surgery Project: Donald Promish, Gábor Cserni, Georges Vlastos, Jan Van de Steene, and Guy Storme.

REFERENCES

1 Vinh-Hung V, Verschraegen C, for the Breast Conserving Surgery Project. Breast-conserving surgery with or without radiotherapy: pooled-analysis for risks of ipsilateral breast tumor recurrence and mortality. J Natl Cancer Inst 2004;96:115–21.[Abstract/Free Full Text]

2 Levitt SH, Aeppli DM, Nierengarten ME. The impact of radiation on early breast carcinoma survival. A Bayesian analysis. Cancer 1996;78:1035–42.[CrossRef][ISI][Medline]

3 Rutqvist LE, Rose C, Cavallin-Stahl E. A systematic overview of radiation therapy effects in breast cancer. Acta Oncol 2003;42:532–45.[CrossRef][ISI][Medline]

4 Sutton AJ, Abrams KR, Lambert PC, Hellmich MAG, Jones DR. Meta-analysis in practice: a critical review of available software. Poster, 14th Annual Meeting of the International Society of Technology Assessment in Health Care, Ottawa, June 7–10 1998. Available at: http://www.prw.le.ac.uk/epidemio/personal/ajs22/meta/soft_p.pdf. [Last accessed: June 8, 2004.]

5 Sutton AJ, Abrams KR, Jones DR, Sheldon TA, Song F. Systematic reviews of trials and other studies. Health Technol Assess 1998;2:1–276. Available at: http://www.ncchta.org/execsumm/summ219.htm. [Last accessed: June 8, 2004.]

6 Bloom BS, de Pouvourville N, Libert S. Classic or Bayesian research design and analysis. Does it make a difference? Int J Technol Assess Health Care 2002;18:120–6.[ISI][Medline]



             
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