Breast Brachytherapy
Partial breast radiotherapy an alternative to whole breast radiotherapy in Breast Cancer
Breast cancer is the most common cancer site among women and is expected to account for about 30% of new cancer cases, approximately 180,000 cases annually. Breast carcinoma is second only to lung cancer in cancer death rates among women. Although the number of deaths of women from breast cancer appears to be leveling off, our goal, in the 21st century, must be to see a significant decline in death from breast cancer as well as unnecessary side effects from treatment, through the application of improved treatment techniques.
An innovative type of radiation therapy technique may prevent unnecessary radiation exposure to the whole breast in patients who undergo breast conserving treatment for early stage breast cancer. This treatment technique is called breast brachytherapy, and involves outpatient delivery of radiation to the quadrant of the breast containing the primary tumor.
Breast Brachytherapy has played a role in breast cancer treatment for nearly 100 years. In the 1960’s, 1970’s, and 1980’s, as breast conserving treatments were being explored, interstitial implants regained favor as a boost modality after whole breast external beam radiotherapy. Subsequently, at most center, electron beam treatment supplanted implants as the boost treatment of choice because of it’s availability, minimal invasiveness, and radiation safety.
Over the past two decades, breast conserving treatment, consisting of lumpectomy followed by external beam radiotherapy, has become a standard treatment option for patients with early stage breast cancer. Many prospective, randomized trials have demonstrated similar disease free and overall survival rates between breast conserving therapy and mastectomy. Breast conserving therapy has the advantage of superior cosmetic outcome with breast preservation, and less emotional trauma related to body image.
However, some disadvantages to breast conserving treatment include the prolonged treatment course required to deliver external beam radiotherapy, as well as potential side effects, related to the need to irradiate a portion of the adjacent lung, and possibly the heart, in order to treat the entire breast. The six to seven weeks of daily treatment may pose a problem to some patients such as working women, elderly patients, and those living a significant distance from a radiotherapy facility. In some cases, women may elect a non breast conserving management only due to these time and convenience restraints.
Since patterns of failure studies have demonstrated that the majority of breast recurrences are in the same quadrant as the original tumor,, large volume breast brachytherapy, delivering radiotherapy to only the quadrant containing the original tumor, is expected to offer equivalent of not better local control and survival results while reducing the radiation exposure to surrounding normal tissues, and delivering the entire course of treatment over five to ten days postoperatively.
A pilot trial of wide-volume brachytherapy was performed at the Ochsner Clinic with unifocal breast cancers less than 4cm with negative margins and zero to 3 metastatic axillary nodes. Fifty-two patients have been followed a median of 4.5 years. There have been no breast recurrences and the cosmetic outcome was equivalent to external beam radiotherapy in a matched-pair analysis.
A Phase II Radiation Therapy Oncology (RTOG) trial with more strict eligibility criteria and quality assurance measures opened in May 1997 to study the reproducibility, clinical feasibility, quality assurance, treatment results, and cosmesis with this technique. More than 300 patients have been treated with this technique and results show local recurrence rates comparable to external beam radiotherapy. A Phase III Randomized trial comparing breast brachytherapy with external beam radiotherapy in comparable patients is underway.
Patients who are candidates for breast brachytherapy, are those with small primary tumors less than or equal to 3cm in size, negative microscopic lumpectomy margins, and no more than zero to three involved axillary lymph nodes.
