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MammoSite Technical Bulletin

On April 15th, the National Surgical Adjuvant Breast and Bowel Project (NSABP) and the Radiation Therapy and Oncology Group (RTOG) issued amendment #5 to the current NSABP-39/RTOG 0413 phase III study. The amendment was prompted by the fact that since the initiation of the trial in 2005, three FDA-cleared, single-entry multi-lumen, intra-cavitary devices became commercially available:

MammoSite® (Multi-Lumen), Contura® MLB (Multi-Lumen Balloon), and SAVI® Radiation Therapy Systems

This is great news for APBI in general and brachytherapy device therapy in particular.  We wanted to ensure that you had the most recent information as well as some very pertinent clinical highlights below from the B-39 protocol. 

All three of these intracavitary devices preserve the single-entry concept while providing the radiation oncologist with the ability to improve dosimetric coverage of the target and reduce the dose to the nearby rib and skin when needed.  These devices provide the potential to expand the number of patients who can be appropriately treated with an intracavitary brachytherapy approach.

The changes made in Amendment #5 were constructed to allow the use of these additional protocol-specified multi-lumen intracavitary device options on the NSABP B-39/RTOG 0413 study.  All multi-lumen APBI devices (MSML, Contura and SAVI) may now be included in the B-39 trial.

We have highlighted some of the important B-39 protocol information below from Section 13 for your reference.  Please familiarize yourself with the entire B-39 protocol as we have listed only a few of the most critical excerpts below.  Essentially, these criteria address the following dosimetric minimal standards that must be met concurrently:

1. ≥90% of the prescribed dose (PD) ≥90% of the target volume (PTV_EVAL)
2. Maximum skin dose ≤ 145% of the PD
3. Minimum balloon/device surface-skin distance of 5 mm
4. V150 ≤ 50 cc
5. V200 ≤ 10 cc

13.1.4 Determination of appropriateness for treatment

Minimal balloon/device surface-skin distance – It will be considered acceptable for treatment after appropriate treatment planning documents that the maximum skin dose at any point is < 145% of prescription dose, assuring that the skin dose does not exceed acceptable limits.

Despite the ability of the multi-lumen devices to dose shape, a minimum skin thickness of 5 mm is required for all three intracavitary treatment devices. This rule was maintained in order to preserve the consistency of the trial data and because little published data are available documenting the safety and efficacy of thinner skin spacing. Concerns still exist about adequate tissue oxygenation and possible tissue necrosis caused by marginal (< 5mm) skin thicknesses. Similar to the ASTRO Consensus Panel Guidelines, the NSABP-39/RTOG 0413 felt that no variation in this parameter should be allowed until sufficient published data exist to support the safety and efficacy of thinner skin spacing.

Normal breast tissue volume parameters To ensure that acceptable dose homogenity is not exceeded while striving to achieve target coverage, the volume of tissue receiving higher doses will be limited.  The actual volume of tissue receieving 150% (V150) and 200% (V200) of the prescribed dose will be limited to < 50 cc and < 10 cc, respectively.  (V150 will be the volume of tissue receiving 150% of the prescribed dose, and V100 will be the volume of tissue receiving the prescribed dose.)

The NSABP-39/RTOG 0413 PI’s rightly felt that all three devices are intra-cavitary and as such, must meet the dosimetric criteria established in the protocol which have been documented (in published clinical data) to be safe (when using this form of APBI). Deviations from these parameters are considered protocol violations because of unacceptable dosimetry and the potential for the development of significant late effects (i.e., fat necrosis) related to hot spots.

Please note that all of these dosimetric criteria must be met concurrently in order for any of these new devices to be allowed on the phase III trial.

As previously stated – this is great news for APBI and we at Hologic wanted to apprise you of this amendment and assure you that MammoSite ML radiation therapy system is capable of meeting all dosimetric parameters of Section 13.1.4 of the NSABP-39/RTOG 0413 protocol.  If you have any questions please contact your sales representative or Hologic Customer Service at:

Phone: 1-800-442-9892 - Option 5
Fax: 1-800-409-7591
Email at: CSPCustomerService@Hologic.com

  1. 05/27/11 – Technical Information Bulletin regarding the National Surgical Adjuvant Breast and Bowel Project (NSABP) and the Radiation Therapy and Oncology Group (RTOG) issued amendment #5 to the current NSABP-39/RTOG 0413 phase III study
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