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. 2013 Feb 1;266(2):685. doi: 10.1148/radiol.12121630

Mammographic Surveillance after Breast Conservation Therapy

D David Dershaw 1,✉, Carol H Lee 1, Elizabeth A Morris 1
PMCID: PMC6940001  PMID: 23362098

Editor

We read with interest the article by Dr Arasu and colleagues (1) in the August 2012 issue of Radiology advocating 6-month rather than annual mammography in women who have undergone breast conservation. The authors’ comments on our observations would be appreciated.

Data in the study show that although mean tumor size was smaller at recurrence in those undergoing more frequent mammography, this did not reach statistical significance (P = .15) for invasive cancers; the same was true for a difference in nodal status (P = .28). There was considerable overlap in tumor size in both groups (mean ± standard deviation, 11.7 mm ± 7.4 in 6-month group and 15.3 mm ± 8.8 in 12-month group). The mean size of invasive recurrences was greater than 1 cm for both groups and only differed by 3.6 mm. The difference in size of tumor recurrence suggested by the authors when presented as less than or more than 1 cm rather than as true size may overstate the real significance in the difference between these two groups.

The authors have defined their two study groups as “compliant,” those undergoing mammography in 6-month intervals (with intervals as short as 3 months), and “noncompliant,” those undergoing mammography at up to 18-month intervals. Differences in patient behavior may indicate other differences in these two populations that have not been appreciated by the authors. In addition, the study is not strictly comparing 6- versus 12-month follow-up but includes intervals that range from 3 to 18 months. There is no doubt that a 15-month interval will have an effect on staging of recurrence.

Footnotes

Disclosures of Conflicts of Interest: D.D.D. No relevant conflicts of interest to disclose. C.H.L. No relevant conflicts of interest to disclose. E.A.M. No relevant conflicts of interest to disclose.

Reference

  • 1. Arasu VA, Joe BN, Lvoff NM, et al. Benefit of semiannual ipsilateral mammographic surveillance following breast conservation therapy. Radiology 2012;264(2):371–377. [DOI] [PMC free article] [PubMed] [Google Scholar]
Radiology. 2013 Feb;266(2):685–686. doi: 10.1148/radiol.12121630a

Response

Vignesh A Arasu *, Bonnie N Joe *,✉, Natalya M Lvoff †, Jessica W T Leung ‡, R James Brenner *,§, Chris I Flowers *, Dan H Moore ∥, Edward A Sickles *

Thank you for the opportunity to clarify our study (1). Recurrences had more favorable prognosis in our compliant cohort with every 6-month follow-up. This was statistically significant on the basis of tumor stage, which is an important predictor of survival (2,3). A 1-cm cut point for invasive cancer size, although not the point of maximum statistical significance in our study, has clinical relevance because it separates stage T1b and smaller cancers from stage T1c and larger cancers. Prognosis is excellent for invasive cancers measuring 1 cm or smaller, with approximately 90% survival at 20 years (4).

As acknowledged, study cohorts defined according to patient compliance introduce potential selection bias. Because we found no meaningful differences in age and family history (major breast cancer risk factors) between cohorts, the magnitude of selection bias may not have been substantial.

Compliance with any mammography screening protocol is customarily measured in ranges of months rather than limiting study to a specific recommended month. The great majority of women in our 6-month and 1-year cohorts underwent follow-up within 2 months of the center intervals, with relatively few undergoing follow-up at 14–18-month intervals. It is unlikely that our outcomes are substantially skewed by women screened at far-from-center intervals.

This is the first study reporting outcomes data on a more frequent than annual screening interval in patients who had undergone lumpectomy. Although more elegantly controlled data would be preferable, and we strongly encourage others to report such data, our study provides suggestive evidence that women may benefit from semiannual rather than annual screening for the first 5 years after lumpectomy.

Disclosures of Conflicts of Interest: V.A.A. No relevant conflicts of interest to disclose. B.N.J. Financial activities related to the present article: none to disclose. Financial activities not related to the present article: has grants pending with the National Institutes of Health; receives royalties from UptoDate. Other relationships: none to disclose. N.M.L. No relevant conflicts of interest to disclose. J.W.T.L. No relevant conflicts of interest to disclose. R.J.B. No relevant conflicts of interest to disclose. C.I.F. No relevant conflicts of interest to disclose. D.H.M. No relevant conflicts of interest to disclose. E.A.S. No relevant conflicts of interest to disclose.

References

  • 1. Arasu VA, Joe BN, Lvoff NM, et al. Benefit of semiannual ipsilateral mammographic surveillance following breast conservation therapy. Radiology 2012;264(2):371–377. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 2. Chances for survival based on cancer stage . Surveillance, epidemiology, and end results (SEER) data. http://ww5.komen.org/Diagnosis/ChancesForSurvivalBasedOnCancerStage.html. Accessed November 17, 2012.
  • 3. Elkin EB, Hudis C, Begg CB, Schrag D. The effect of changes in tumor size on breast carcinoma survival in the U.S.: 1975-1999. Cancer 2005;104(6):1149–1157. [DOI] [PubMed] [Google Scholar]
  • 4. Tabár L, Vitak B, et al. The Swedish Two-County Trial twenty years later: updated mortality results and new insights from long-term follow-up. Radiol Clin North Am 2000;38(4):625–651. [DOI] [PubMed] [Google Scholar]

Articles from Radiology are provided here courtesy of Radiological Society of North America

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