The new findings challenge past studies that showed delivering radiation to a breast with an implant in place causes significant problems in the implant, resulting in poor cosmetic results.
"Past research was based on a small sample of patients and older radiation techniques," said Rosalyn Morrell, M.D., lead author of this Mayo Clinic study. "Therefore, we investigated a larger group of women treated with radiation using newer techniques that refuted the reports of poor cosmetic outcome among patients."
Most women with early-stage breast cancer are able to undergo breast conservation surgery to keep their breast after treatment. Typically, this means that they first have surgery to remove the cancer (a lumpectomy), followed by a course of radiation therapy to kill any cancer cells that may remain. This approach is just as effective as a mastectomy in treating the cancer and is preferred by many women.
More women today are opting to have cosmetic breast implants. As women age, their risk of breast cancer increases, so a fraction of these women will eventually develop breast cancer. These are the patients who would be most interested in preserving their breasts and avoiding mastectomy.
Between 1994 and 2004, researchers reviewed the records of 26 breast cancer patients with previously augmented breasts who were treated with breast conservation surgery and radiation at the Mayo Clinic. All patients had their implants in place before their breast cancer diagnosis. Eighty-five percent of patients followed over a three-year period had favorable cosmetic results following radiation therapy. None of the patients in the study suffered a relapse of their cancer.
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Post-treatment complications included balloon rupture, infections, skin toxicity and seromas (persistence of the cavity where the lump was removed). Study results indicated that balloon rupture occurred in six patients (7 percent) and wound infections occurred in 10 patients (12 percent). No patients had serious skin toxicities from treatment. A palpable seroma was observed in 34 of the patients (40 percent) and persisted beyond six months of treatment in 22 patients (26 percent).
The study also evaluated cosmetic outcome of MammoSite treatment. Cosmetic outcome refers to the physical similarity between the treated breast and the untreated breast. Forty-eight patients (56 percent) had excellent cosmetic outcomes; 32 patients (37 percent) had good cosmetic outcomes; and seven patients (7 percent) had fair cosmetic outcomes.
"Our findings demonstrate that the toxicities associated with MammoSite were similar to results reported in the MammoSite brachytherapy registry trial," said Dr. Beriwal. "The complications were acceptable and the cosmetic outcome was comparable to what we might see with standard external beam radiation." Dr. Beriwal added that follow-up studies will seek to assess the long-term effects as well as the efficacy of the treatment compared with standard external beam radiation therapy and other types of breast brachytherapy.
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