Trials in Breast Brachytherapy - Cancer Specialist Catheryn Yashar, Answers

Recent controversy on breast brachytherapy is sparked by the fact that the number of women receiving the treatment is on the rise even before the American Randomized Prospective Trial has been completed and published. Meanwhile the guidelines by several American societies focus on the cautious selection of eligible candidate to receive brachytherapy as an alternative to Whole Breast Radiation (WBI). Dr. Catheryn Yashar M.D. Oncologist and Brachytherapy Specialist of UC San Diego Moores Cancer Center, sheds light on the concerns impacting brachytherapy offered to women. Q. One of the advantages of brachytherapy is the limited timeframe in comparison to WBI, what are the other benefits of brachytherapy?

A. With partial breast radiation therapy or breast brachytherapy, the treatment depends on the method employed, but from one centimeter to 2 centimeter of the tissue that is at risk to harbor cancer cells is irradiated. So once a woman has a lumpectomy and the tumor is removed, brachytherapy or accelerated partial breast radiation really only treats one to 2 centimeters of tissue surrounding where the tumor used to be. On the other hand whole breast radiation therapy, which takes 3-6 weeks, treats the entire breast. Hence it’s not just the shorter time span but also less tissue is treated with partial breast radiation therapy than with whole breast radiation therapy.

Q. How is the eligibility of a person to receive brachytherapy determined?

A. Among the numerous guidelines published in the United States, the most stringent is from ASTRO (American Society of Therapeutic Radiation Oncology). It recommends into an unsuitable category women that should be treated with partial breast only on an open trial. The suitable category is women over 60 with invasive tumours that are 2 centimeters or less and are ER (Estrogen Receptor) positive. There are also the cautionary group of tumors between 2 and 3 centimeters, women between 50 and 60 years old, ductal carcinoma in situ and some other risk factors. So when a woman is interested in partial breast therapy, I would go over in detail the pathology of the breast cancer and then discuss what we know about partial breast radiation therapy and what we don’t know. We thoroughly discuss the guidelines so that we make the decision on the appropriate treatment together.

Q. To what extent does a doctor’s intervention help a woman with breast cancer decide what treatment (brachytherapy or WBI) is in her best interest?

A. Brachytherapy takes shorter treatment time, and less normal tissue is treated. We go over the unknown details such as the trials that are yet to be published and the risks of both whole breast therapy and partial breast therapy. We discuss that we have to wait for the results of those trials before we are certain that partial breast irradiation is equivalent to the standard of care, which is full breast radiation therapy. I basically walk the women through that data to help them make the choice that is appropriate for them. Many women like partial breast radiation therapy and are happy with it, although in many women it is not considered the standard of care. It is appropriate only for the earliest, lowest risk cancers. But for women in whom it is appropriate and who choose to do it, it is a very convenient method of treatment, where we can conform the dose nicely to area of the breast at most risk for recurrence and limit radiation to the other tissues such as lung, heart, and ribs that don’t harbor cancer cells but are difficult to avoid in whole breast radiation therapy.

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Q. Wouldn’t women be at a disadvantage the longer it takes for the trials to be published?

A. True, but whole breast radiation is available and is an excellent treatment choice. The Hungarians have actually published a randomised prospective trial and then there is another randomised prospective called the TARGIT trial in which case the radiation would be offered in the operating room. The Italians have also recently published a trial on partial breast radiation therapy, so there are trials that are published that suggest that it may be an alternative. But in those trials women tend to be older and at the lowest risk for recurrence and so once again concerning younger women or higher risk breast cancer we have to wait for trials to demonstrate that it’s equivalent. Some women are not comfortable with the lack of data and are very accepting of whole breast radiation therapy. No one is trying to get rid of WBI; we are just hoping that partial breast radiation therapy will be, in appropriate women, a more convenient and less toxic alternative.

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Wonderful advances have been observed in brachytherapy since 2006 that have enabled the physician to shape the dose much better than we could with the original balloon brachytherapy. The type of brachytherapy used in the Hungarian trial, interstitial brachytherapy, involved the placement of multiple catheters through the breast tissue. This method allows the most precise dose shaping to the person’s anatomy but the skill and experience level it requires is much greater and not all physicians are comfortable with that method. The new multicatheter devices are far easier to place and plan so in the appropriate woman a more attractive option.

Source-Medindia