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Considerations for Choosing Partial Breast Irradiation

Considerations for Choosing Partial Breast Irradiation

Question

Dear OncoLink "Ask The Experts,"

What factors need to be considered when choosing partial breast irradiation (type of tumor, size, and stage)? My doctor told me my age (44yo) was also a factor.

Answer

Terry Styles, MD, Assistant Professor of Radiation Oncology at the University of Pennsylvania, responds:

Partial breast irradiation is just one of many new techniques in radiation oncology attempting to make treatment more convenient or to have fewer side effects. In discussing this topic, however, the first thing to understand is that whole breast radiotherapy with daily treatments over six to seven weeks is the standard of care. There are many trials with more than 25 years of data and thousands of patients who have been treated in this manner, all showing good results in terms of survival, side effects, and the cosmetic results. Breast cancer has a long natural history, meaning that it takes many years (more than 10) to be sure that a treatment is effective and that there are no adverse side effects.

At this time, the longest studies evaluating partial breast irradiation ( PBI ) do not use the same techniques we use most frequently today. They appear to show equivalence in terms of recurrence rates and survival and also have good results cosmetically, but since they were done in a different manner it is very hard to say with 100% confidence that the two treatments are equal. PBI has become more popular with the FDA approval of the MammoSite catheter in 2002, and alternative techniques are also being evaluated. While many patients are receiving this treatment, it is still considered experimental.

Most of the available data has looked at peri and post-menopausal patients with small breast cancers (<3cm), negative margins, and no involved lymph nodes. The American Society of Breast Surgeons and the American Brachtherapy Society recommend that patients who will receive PBI should be 45 years or older; have a tumor that is an invasive ductal carcinoma or ductal carcinoma in situ (DCIS) that is less than three centimeters in size (around an inch); have no cancer on the cut edge or margins; have no spread to the lymph nodes. There is currently an ongoing research study that includes others in whom it would not normally be recommended, for instance, women between 18 and 45 years of age and women with 1-3 involved lymph nodes. It will be a long time before we know the results of this study, so I would only treat women in this category as part of a trial.


Mammosite catheter in place


Mammosite catheter