Brachytherapy, a type of radiation treatment that uses radioactive implants, has gained popularity in the U.S. in the context of breast conserving treatment (which typically consists of lumpectomy plus radiation). Treatment only lasts one week compared to five to seven weeks for conventional whole breast irradiation. However, a few observers have raised questions concerning the increasing use of brachytherapy, especially in light of a lack of randomized clinical trials comparing brachytherapy's effectiveness with that of whole breast irradiation. There have also been concerns about patient selection; brachytherapy appears sometimes to be offered to women who are not good candidates for it. Another potential problem with any form of partial breast irradiation is that it does not treat possible dispersal of cancer cells in the biopsy needle tract.
Now a new study has reported that brachytherapy has comparable survival outcomes as whole breast radiation. However, rates of side effects and mastectomy are higher in women undergoing brachytherapy, which is inconsistent with hoped-for advantages of what is in some respects less extensive treatment.
Brachytherapy patient selection
The best candidates for brachytherapy have small, early stage tumors. Women who are treated with brachytherapy or other forms of partial breast irradiation must have localized disease that has been completely removed during surgery. This means that the pathology report must show clear surgical margins, no residual in situ disease, and, ideally, no lymphovascular invasion (invasion of the cancer cells into the blood vessels or lymphatic channels). Women with multifocal or multicentric disease are not good candidates because they have a higher probability of additional undetected cancer in the breast.
Risk of needle tract seeding is theoretical only when whole breast is irradiated
The potential for tumor seeding along the needle path has long been a concern regarding breast cancer needle biopsies. In fact, evidence exists to suggest that such seeding can and does occur up to half of the time. However, studies that have examined the question as to whether such seeding has an impact on survival have been reassuring. Apparently, most cancer cells dispersed in such a manner are not able to survive. Nevertheless, cases have been described in which local recurrences were found in the biopsy path.
Radiation treatment appears to be an effective method for destroying any breast cancer cells dispersed in the breast by needle biopsies. However, the needle tract must be part of the radiation field. This is automatic in the case of whole breast irradiation, but not for brachytherapy.
Latest research finds brachytherapy is effective but has some drawbacks
The study referenced at the beginning of this news article was designed to investigate outcomes of women who undergo brachytherapy. The authors decided to perform this retrospective observational study since results of long-term prospective trials comparing brachytherapy with whole breast irradiation will not be available for years. The study included 92,735 women on Medicare diagnosed with breast cancer during the period 2003 to 2007. All of the women received a lumpectomy. This was followed by brachytherapy for 6,952 of the women and whole breast irradiation for 85,783. The women were followed through 2008.
The main outcomes studied were subsequent mastectomy (representing a failure to preserve the breast) and death. In addition, postoperative infections and other complications were compared. The five-year rate of mastectomy was found to be higher in women treated with brachytherapy (3.95%) compared to whole breast irradiation (2.18%). However, five-year overall survival was 87.66% among women treated with brachytherapy compared to 87.04% in women treated with whole breast irradiation, results which were equivalent.
Brachytherapy was associated with more infections (16.20%) than whole breast irradiation (10.33%). In addition, brachytherapy was associated with more noninfectious postoperative complications (16.25%) than whole breast irradiation (9.00%), higher five-year incidence of breast pain (14.55% compared to 11.92%), fat necrosis (8.26% compared to 4.05%), and rib fracture (4.53% compared to 3.62%).
The authors conclude that treatment with brachytherapy is associated with worse long-term breast preservation and increased complications but no difference in survival when compared to whole breast irradiation in a population of older breast cancer patients.
Please see our article on breast cancer diet during radiation treatment for more information.