Women 40 years and younger with early-stage breast cancer who receive an additional high dose of radiation (boost dose) after undergoing lumpectomy and standard radiation treatment are almost twice as likely to be free of cancer 10 years after treatment compared to those who don't receive the boost dose. The study results were presented at the Plenary I session on October 29, 2007, at the American Society for Therapeutic Radiology and Oncology's 49th Annual Meeting in Los Angeles.
Although younger women benefited most from an extra dose of radiation, the findings show that women of all ages who had a boost dose of radiation after standard treatment were more likely to be cancer-free over a 10-year period.
The study involved 5,318 women who underwent lumpectomies and whole breast radiation treatment as part of their breast conserving therapy for Stage I and Stage II breast cancer and was evaluated 10 years later. Researchers wanted to determine if a boost dose of radiation following this treatment would decrease the risk of breast cancer recurrence. In addition to this, a sub-group of 1,725 patients were evaluated to find out the highest risk factors for localized breast cancer recurrence.
For patients with early stage breast cancer, the current standard treatment involves lumpectomy followed by radiation therapy to the breast over a six to eight week period to kill any remaining cancer cells. In this study, an additional boost of high-dose radiation was given after conventional radiation therapy to the lumpectomy site where the tumor was removed to potentially increase the chances of a cure.
With a lumpectomy, the surgeon removes the tumor, along with nearby healthy tissue. If the outside of the tumor, or margin, has cancer cells present, then it's considered a positive margin. If it's unclear, or a very small distance, then doctors call it a close margin. Women who have positive and close surgical margins are at a higher risk of breast cancer returning, compared to those who have negative margins that are free of cancer.
The study also found that early-stage breast cancer patients who were at a younger age are most likely to have their cancer come back (recurrence), particularly those who have positive surgical margins. This study and previous ones have shown that young patients with early-stage breast cancer have a higher risk of breast recurrence, compared to older patients because their cancer tends to be more aggressive.