Accelerated Intensity Modulated Radiation Therapy (AIMRT) to the Breast After Segmental Mastectomy

Despite level I evidence of comparable efficacy to that of mastectomy, breast conserving therapy (BCT) remains underutilized in the United States. In 1990, the National Institutes of Health (NIH) Consensus Development Conference concluded that BCT was the appropriate method of treatment for the majority of women with early stage I and II breast cancer. However, this subsequently only translated in a moderate increase in the utilization of BCT, shifting from 34% to 60% for stage I breast cancer and from 19% to 39% for stage II breast cancer.

There appear to be multiple causes for underutilization. The demands of the standard radiation schedule probably play the main role. Generally, post-lumpectomy radiation therapy consists of 4 to 5 weeks of whole breast radiation of a total dose 45 to 50 Gy in 23-25 fractions, usually followed by a boost of 10 to 16 Gy in 5-8 fractions to the tumor bed area. The total length of treatment is 5-7 weeks, commonly six weeks. Practically, women who choose BCT automatically commit to a regimen of approximately six weeks of daily radiation visits (Monday to Friday) to complete the local management of their breast cancer. For many women, concerns about this commitment are likely to influence the choice for mastectomy instead of breast preservation since only 40-60% of women who meet criteria for BCT actually undergo the procedure. In addition to possible biases of the primary health care provider affecting these choices, it is known that distance from RT treatment facilities also plays an important role in women's choice for mastectomy instead of BCT. Unfortunately, 15-30% of patients who have actually selected BCT, in particularly older patients and those with 2 or more co-morbid conditions, do not receive postoperative RT. These facts warrant a critical assessment of standard radiation therapy in this clinical setting.

The actual standard approach to post-segmental mastectomy adjuvant radiation at our institution consists of surgical excision followed by 6 weeks of breast irradiation for a total of 30 fractions of 2 Gy each, 23 (46 Gy) to the whole breast while 7 to the original tumor bed (14 Gy). Instead, the women in this study will only receive 15 larger radiation fractions (2.7 Gy) to the entire breast with a concomitant boost to the tumor bed (2.7 Gy + .5 Gy, total 3.2 Gy per fraction). All women will be treated prone to best apply IMRT techniques while avoiding the rest of the body.

Treatment with fewer fractions over a shorter duration of time offers several advantages, provided it is as effective as the conventional treatment regimens and without added morbidity. The potential advantages include: 1) less time away from homes, families and jobs; 2) less cost associated with travel and time away from work; 3) ease the demand on radiation treatment resources and produce savings to the health-care system. Moreover, treatment prone assures that only minimal dose of radiation is delivered to the lung, heart and to the controlateral breast.

Patients will have completed all breast surgical procedures prior to accrual into this protocol in order to establish eligibility criteria. All patients will then be treated prone with 2.7 Gy/fraction delivered in 15 fractions over a 3-week period for a total dose of 40.5 Gy.

All patients will be followed 1, 3, 6, 12 months after treatment course, then yearly thereafter.