CHICAGO – Less radiation may be just as good as the standard dose in treating women with early breast cancer, according to a study presented Sunday in Chicago at the world’s biggest cancer meeting.
The British study, the largest to look at the question, found that fewer, larger doses of radiation were as effective at preventing recurrence and did not cause more side effects.
If the results are borne out by similar ongoing studies in the U.S., they could offer a welcome alternative to many American women who now must undergo six to seven weeks of post-surgical radiation.
About 250,000 U.S. women are diagnosed with breast cancer each year. The vast majority are eligible for breast-conserving surgery, or lumpectomy, in which the tumor is removed and the breast then irradiated to prevent a recurrence of the cancer.
Studies have shown that many of those women choose mastectomy, or removal of the entire breast, to escape the burdensome radiation therapy. In addition, up to one-third of women who get lumpectomies skip the recommended radiation, greatly increasing their risk of relapse.
“Shorter regimens offer an alternative to those women,” said Dr. Gary Freedman of Fox Chase Cancer Center in Philadelphia.
Freedman, who was not involved in the British study, noted that two other foreign studies have reached similar conclusions and that he and others in the U.S. are researching shorter courses of radiation therapy.
Dr. Julie Gralow of the University of Washington said her cancer center gets many patients from Alaska who cannot commute or move to Seattle for radiation therapy. She said the shorter regimen “makes sense – we might do it, especially for those patients.”
In the British study, more than 4,400 women were randomly assigned to receive either the standard course of radiation therapy – 50 Gray (or Gy, a standard unit of radiation exposure) delivered in 25 installments over five weeks – or one of two courses with less total radiation. In one of the experimental courses, the women got 40 Gy delivered in 15 installments over three weeks.
After five to six years of follow-up, there was no significant difference between the groups in the rate of recurrence, and there were fewer side effects, such as skin discoloration or shrinkage, in the women who got less radiation.
“These findings suggest that women can safely undergo a less demanding course of radiation therapy without appearing to increase their risk of recurrence,” said Dr. John Dewar of the University of Dundee in Scotland and one of the authors of the study.
Dewar presented his findings Sunday at the annual meeting of the American Society of Clinical Oncology. More than 31,000 cancer experts are attending the five-day meeting at McCormick Place.
Freedman said he did not expect most American doctors to adopt the British radiation schedule because most American breast cancer patients get more radiation than the standard used in the British control group and because the level of side effects in the British study – more than one-third of the women had some negative results – would not be acceptable in the U.S.
The standard in the U.S. is 50 Gy over five weeks to the entire breast, followed by a “boost” to the lumpectomy site of 10 to 14 Gy, for a total of six to seven weeks of treatment.
Freedman’s center recently completed a study of 75 women who got 20 doses of radiation over four weeks. The researchers combined the “boost” and the whole-breast irradiation, so that the whole breast got a total of 45 Gy and the lumpectomy site got an additional 11 Gy. They used a newer technology called intensity-modulated radiation therapy.
Freedman said his patients have been followed for only two to three years, but so far, fatigue and skin reactions are no worse than from the standard six- to seven-week course.
“We’ll continue to follow them for five years,” he said.
Although breast cancer can come back anywhere in the body and at any time, most local recurrences – that is, in the same breast – happen within five years.
In other research presented Sunday at the oncology meeting:
A study from the University of Texas found that black women are not benefiting from the progress made in treating advanced (metastatic) breast cancer.
An analysis of national statistics found that the average white woman diagnosed between 1988 and 1993 lived 20 months, compared with 17 months for the average black woman. A decade later, white survival had increased to 27 months, but black survival remained the same.
The study did not reveal whether the racial gap is due to biological differences or differences in treatment.
A drug used to treat narcolepsy and promote wakefulness was found to combat “chemo brain” in a small group of breast cancer survivors. The drug, modafinil (Provigil), improved memory, concentration and learning, which are commonly impaired by chemotherapy.
A test that is already helping doctors offer personalized treatment to women with early breast cancer appears useful for some patients with more advanced cancer.
The test, Oncotype DX, uses a 21-gene signature to predict which patients are likely to relapse and which can safely forgo chemotherapy. A study suggested that the test provides accurate information regarding the likelihood of recurrence for patients with hormone-sensitive tumors, even if the cancer has already spread to nearby lymph nodes.
A pill that starves tumors by cutting off their blood supply proved better than the standard of care – interferon – in patients with advanced kidney cancer. The drug, Sutent, kept the disease from progressing for an average of 11 months, compared with five months for interferon.