BOSTONA 16-Gy radiation boost can cut the local recurrence rate
by more than half at 5 years for younger breast cancer patients
receiving lumpectomy with radiation therapy, according to European
Organization for Research and Treatment of Cancer (EORTC) clinical
trial results presented at the American Society for Therapeutic
Radiology and Oncology meeting.
Harry Bartelink, MD, PhD, professor of radiotherapy, Netherlands
Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam,
reported that the boost reduced local recurrence rates by 54% in
women under age 40 and by 48% in women aged 41 to 50. While younger
patients benefited more than older patients, the oldest patients had
a drop of 32%. Overall, the recurrence rate was cut by 41%.
These results were so striking at a median follow-up of 5.1 years
that Dr. Bartelink reported them to ASTRO midway through the 10-year
study of 5,569 women. They had to change their standard of
practice. This is the largest study ever done. It will not be
repeated within the next 10 years, he told ONI.
Jay R. Harris, MD, of the Dana-Farber Cancer Institute, called the
study a blockbuster. He told the ASTRO audience,
This trial demonstrates that the boost works. Dr. Harris
said the full impact on survival would not be known until the study
passes 10 years, but that he never thought the results seen so far
could be achieved with minimum cosmetic effects.
Eleven European countries participated in the trial, with 32
radiation therapy departments reporting cases. Strict quality
assurance procedures were implemented to ensure that all patients
received the same standard of care whether they enrolled at a large
teaching hospital or a smaller center in their home community.
The patients all had stage I or II breast cancer, and no tumors were
greater than 5 cm in diameter. The average age of the participants
was 55 years old, with 1,334 women between the ages of 41 and 50, and
449 aged 40 or under; 60% of the women were postmenopausal, 11%
received chemotherapy, and 18% received tamoxifen (Nolvadex).
All the women underwent tumorec-tomy followed by whole breast
irradiation of 50 Gy. The vast majority5,318 patientshad
a microscopically complete excision and were randomized to receive no
boost or the 16-Gy boost. The remaining 251 patients had incomplete
excisions and were randomized between boost doses of 10 Gy and 26 Gy.
Among those who had a complete excision, local recurrences were
reported for 182 women in the no-boost group vs 109 patients who
received the 16-Gy boost. This results in 5-year actuarial recurrence
rates of 6.8% and 4.3%, respectively.
Age was the most important single factor for local
control, Dr. Bartelink said, adding that the researchers are
currently studying the womens DNA to try to find out why breast
cancer is more aggressive in the younger women. The key appears
to be that you have to be more aggressive in treating breast cancer
in these women, he said.
A panel assessed the cosmetic results at 3 years, rating them as
excellent/good in 86% of the no-boost group and 71% of the women who
received the boost. Of course, the boost has an impact on
cosmetic outcome, Dr. Bartelink said, but it must be
weighed against the medical benefit afforded by the boost. There is a
large positive impact on local control and only a small negative
impact on cosmetic outcome.
The researchers plan to do an analysis of local control and survival
at 10 years, he added. They do not see a difference in survival at
this point. Nine of 10 participants (91%) were alive 5 years after