Rinaa Punglia, MD, MPH
Older women who have had breast cancer surgery have a greater risk of
the cancer returning if they delay their post-surgical radiation
treatment, report Dana-Farber Cancer Institute scientists.
The study, which involved more than 18,000 women age 65 and older who
had breast cancer, found that those who started radiation treatment
more than six weeks after breast-conserving surgery were more likely to
have a local recurrence than those whose radiation treatment started
within six weeks of surgery. The findings are being published online by
the British Medical Journal.
Rinaa Punglia, MD, MPH,
a radiation oncologist at Dana-Farber and Brigham and Women's Hospital
and the study's lead author, said she and her colleagues conducted the
research to address scientifically the debate about the "appropriate
interval between surgery and radiation treatment, or radiotherapy, and
its impact on treatment outcomes."
Post-surgical radiotherapy is designed to destroy remaining cancer cells following the removal of a localized breast tumor.
Punglia said four to six weeks after surgery is widely viewed as a
safe interval for beginning radiotherapy, which typically is
administered five days a week for six weeks.
The researchers reviewed Medicare database records of 18,050 women
with early stage breast cancer to assess whether the timing of when
radiotherapy started following surgery affected outcomes.
These women were treated between 1991 and 2002 with lumpectomy and
radiation, but not chemotherapy. Thirty percent of women began
radiotherapy six or more weeks after surgery.
For the overall group, slightly more than 4 percent of the women
experienced a local recurrence. The risk increased to about 5 percent,
approximately a 19 percent jump, when the surgery-radiotherapy interval
was longer than six weeks.
The researchers found that there was no "threshold" at which the risk
suddenly rose — it increased incrementally day by day. "There isn't a
large difference between 43 days instead of 41," commented Punglia. "The
day-to-day risk increase is very small."
The rise in breast-conserving surgery in the past two decades has
fueled greater demand for radiotherapy, and might be one cause of longer
waiting times.
The study revealed more delays in areas such as the Northeast, where
the procedure is more common, and fewer delays in the southern states,
where breast-conserving surgery is less common.
Waiting times were also longer in cases involving African-American
and low-income women, but the study did not pinpoint the exact source of
the delay.
"It could be factors such as access to care, the patients' ability to
navigate the healthcare system, or physician referrals," said Punglia.
Although the study focused on older women, the findings have implications for younger women.
"It's possible that the increased risk we identified in older women
could be magnified in younger women, whose tumors are biologically
different and tend to be more aggressive," said Punglia, who is also an
assistant professor of radiation oncology at Harvard Medical School.
The study's other authors are Bridget Neville, MPH, and Jane Weeks,
MD, MSc, of Dana-Farber; Craig Earle, MD, formerly of Dana-Farber and
now of the Ontario Institute for Cancer Research, Toronto; and Akiko
Saito, MD, PhD, formerly of Dana-Farber and now of Nagoya Medical
Center, Japan.
The research was supported by grants from the National Institutes of Health and the American Society of Clinical Oncology.