Largest known series of data examining the sequencing of tamoxifen and radiation

Fox Chase Cancer Center researchers say the sequence of tamoxifen and radiation following lumpectomy for early-stage breast cancer patients does not affect disease control, survival or complication rates, but administering tamoxifen concurrently with radiation has negative cosmetic results.

These findings of this study, the largest known series of data examining the sequencing of tamoxifen and radiation, were presented today at the 47th Annual Meeting of the American Society for Therapeutic Radiology and Oncology in Denver, Colo.

"Prior to this study, the sequencing of radiation and tamoxifen following lumpectomy had not been well-established," explained Penny Anderson, M.D., a radiation oncologist at Fox Chase Cancer Center in Philadelphia and lead author of the study. "Some studies have suggested a potential negative effect of tamoxifen on radiosensitivity when the drug was administered during radiation treatments, while other studies have not demonstrated an adverse effect."

Anderson's study included 1,088 women with stage I/II breast cancer who underwent breast-conserving surgery and radiation therapy and received adjuvant tamoxifen (with or without chemotherapy) between 1982 and 2004. Of these, 699 patients received tamoxifen after completing radiation (sequential) and 389 patients received tamoxifen during radiation therapy (concurrent).

There were no statistically significant differences observed between the sequential group and the concurrent group for disease control and survival. However, there was a statistically higher rate of excellent/good cosmesis in the sequential group compared to the concurrent group (95 percent versus 88 percent).

"Previous studies have shown that quality-of-life issues such as the appearance of the affected breast after treatment is important to women," said Anderson. "We continue to recommend sequential sequencing of tamoxifen and radiation, but concurrent administration has acceptable outcomes if required by a clinical trial or delay in the time of radiation after surgery or chemotherapy."

Other authors of the study include radiation oncologist Gary Freeman, M.D., and biostatisticians Tianyu Li, Ph.D., and Eric Ross, Ph.D., all of Fox Chase Cancer Center.

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