MammoSite and interstitial brachytherapy for accelerated partial breast irradiation

Factors that affect toxicity and cosmesis

Authors

  • Neenad M. Shah M.D.,

    1. Department of Radiation Oncology, Tufts-New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts
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  • Todd Tenenholz M.D.,

    1. Department of Radiation Oncology, Medical College of Virginia of Virginia Commonwealth University Health System, Richmond, Virginia
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  • Douglas Arthur M.D.,

    1. Department of Radiation Oncology, Medical College of Virginia of Virginia Commonwealth University Health System, Richmond, Virginia
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  • Thomas DiPetrillo M.D.,

    1. Department of Radiation Oncology, Rhode Island Hospital/Women and Infants' Hospital, Brown University School of Medicine, Providence, Rhode Island
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  • Bruce Bornstein M.D., M.B.A.,

    1. Department of Radiation Oncology, Tufts-New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts
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  • Gene Cardarelli M.Sc., M.P.H.,

    1. Department of Radiation Oncology, Rhode Island Hospital/Women and Infants' Hospital, Brown University School of Medicine, Providence, Rhode Island
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  • Zhen Zheng Ph.D.,

    1. Department of Radiation Oncology, Rhode Island Hospital/Women and Infants' Hospital, Brown University School of Medicine, Providence, Rhode Island
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  • Mark J. Rivard Ph.D.,

    1. Department of Radiation Oncology, Tufts-New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts
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  • Seth Kaufman M.D.,

    1. Department of Radiation Oncology, Tufts-New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts
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  • David E. Wazer M.D.

    Corresponding author
    1. Department of Radiation Oncology, Tufts-New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts
    • Department of Radiation Oncology, Tufts-New England Medical Center, Tufts University School of Medicine, 750 Washington Street, Box 359, Boston, MA 02111
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    • Fax: (617) 636-6131


Abstract

BACKGROUND

In interstitial brachytherapy (IB), cosmesis and toxicity correlate with volume of tissue irradiated, dose homogeneity index (DHI), and adjuvant doxorubicin/cyclophosphamide based chemotherapy (ACCT). MammoSite brachytherapy (MSB) irradiates smaller volumes than IB, and lower dose homogeneity does not appear to affect toxicity. However, clinical experience suggests that other factors may also play an important role in cosmesis and toxicity with MSB. We reviewed our prospectively maintained data base of women who underwent accelerated partial breast irradiation (APBI) to assess this issue.

METHODS

Beginning in September 1995, 115 women were enrolled in a trial evaluating APBI as monotherapy after lumpectomy. The first 75 eligible patients received IB, and the most recent 28 eligible patients received MSB. All patients received 34 gray (Gy) in 10 twice-daily fractions through high-dose rate iridium-192 brachytherapy; 19% of patients in the IB group and 0% of patients in the MSB group received ACCT.

RESULTS

At 1 year after treatment, MSB caused significantly less Grade 2–4 subcutaneous fibrosis (as graded by a radiation oncologist according to the Radiation Therapy Oncology Group/Eastern Cooperative Oncology Group system) compared with IB (10.7% vs. 32%; P = 0.04). However, when only ACCT-naïve patients in the IB group were compared with patients in the MSB group, this finding became nonsignificant. Among the patients who received MSB, significantly smaller volumes were irradiated, and the DHI was lower.

CONCLUSIONS

Current studies suggest an improved toxicity profile with MSB compared with IB that is attributed to lower irradiated volumes with MSB. When only chemotherapy-naïve patients were compared, however, toxicity and cosmesis were found to be similar between MSB and IB, suggesting a more complex interplay between irradiated volumes, DHI, and chemotherapy. The relation of ACCT to toxicity in this scenario is intriguing and warrants further investigation. Cancer 2004. © 2004 American Cancer Society.

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