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Mammosite

After a lumpectomy when radiation is necessary, it may be possible to complete the radiation in 5 days, rather than the usual six weeks, using the mammosite technique (go here and for scientific studies go here and here, and here, and see RTOG 95-17 and RTOG 0413 and read the recent updates on partial breast irradiation here and here

The guidelines for patient suitability is noted here and from the ASCO consensus guidelines here and here

 

After a lumpectomy a tube or catheter is left behind in the cavity where the tumor was removed and later in the radiation clinic this tube is attached to a radioactive wire that radiates the area around the lumpectomy site, instead of treating the whole breast. This is called "partial breast irradiation" and is currently being studied and compared to more traditional radiation to the whole breast to see if the results are as effective

The original balloon applicator was Mammosite (noted below). Other technologies include the SAVI applicator here, and the CONTURA here.

The MammoSite device is placed at the time of lumpectomy or during a separate procedure post-lumpectomy. The balloon can be inflated to variable sizes to accommodate the individual cavity. An 192Ir radiation source, connected to a computer-controlled high-dose rate (HDR) remote afterloader, is inserted into the balloon to deliver the prescribed dose of radiation. Once the therapy is concluded, the balloon is deflated and the catheter is removed.

 

Benefits of MammoSite RTS:
  • Radiation therapy can be completed in up to 5 days.
  • MammoSite RTS places the radiation source inside the lumpectomy cavity, delivering radiation to the area where cancer is most likely to recur.
  • The amount of radiation to healthy tissue is limited, potentially minimizing side effects.
  • The therapy is given on an outpatient basis.
  • Studies have shown cosmetic results to be good/excellent in 88% of patients.
  • Patient satisfaction has been overwhelmingly positive.
 
 

Treatment Procedure
The MammoSite balloon catheter can be placed at the time of lumpectomy or up to 10 weeks post-surgery. Catheter placement is performed either during the surgical procedure under general anesthesia or in an outpatient procedure room under local anesthesia.

The MammoSite catheter is inserted into the surgical cavity through a separate pathway created by a trocar, or via the lumpectomy scar. The balloon end of the catheter is inflated with saline and contrast agent to allow the surrounding tissue to conform to the balloon, the exit site is dressed, and the patient is sent home.

Once the patient has sufficiently recovered from surgery (typically the next day), she is referred to her radiation oncologist for CT of the balloon in the breast and treatment planning.

Radiation therapy is provided on an outpatient basis. During therapy, an 192Ir seed (attached to a high-dose rate [HDR] remote afterloader) is inserted into the inflated balloon for a short duration (typically less than 10 minutes). When used as primary radiation therapy, 2 treatments are administered per day, for up to 5 days, to deliver the prescribed radiation dose (typically 34 Gy). When used as a boost with external beam radiation, a typical prescription requires treatment for 1-2 days.

After radiation therapy is concluded, the balloon is deflated and the MammoSite catheter is easily removed.