Thousands of patients can avoid chemo
Breast cancer study focused on women in ‘grey area’
TORONTO — When Lisa Freedman was diagnosed with breast cancer, a genetic test of her tumour suggested chemotherapy would have no effect on the risk of recurrence, allowing her to safely skip the treatment and its dreaded side-effects.
“When the test came back, it showed that I would have a 13 per cent chance of recurrence if I had chemo and a 12 per cent chance if I didn’t have chemo,” said the Toronto lawyer, 61.
“So that became an easy nochemo decision,” said Freedman, who has been cancer-free for two years.
A recently published U.S.-led study of more than 10,000 women whose tumours were tested determined that most patients with early-stage estrogen-positive breast cancer and no lymph-node spread should be able to avoid chemo and be treated with surgery, radiation and a hormoneblocking drug like tamoxifen alone.
The study is the largest ever performed looking at breast cancer treatment, and its results are expected to spare thousands of women in Canada each year from having to undergo rounds of chemotherapy and its harsh side-effects.
Funded by the U.S. National Cancer Institute, with additional funding from the Canadian Cancer Society Research Institute, the research looked at women with breast cancer with an intermediate risk of recurrence, based on their scores from the genetic test. Previously, scores from the Oncotype DX test, used since 2004, allowed doctors to sort out women at high risk and low risk of recurrence to determine whether they would benefit from chemotherapy. But women with in-between scores fell into a grey area.
That’s what the study, which included 10,253 women aged 18 to 75, set out to determine, with participants randomized to receive chemo plus a hormone dampening drug or that medication alone. The results were stunning. After nine years, the findings put the women virtually in a dead heat: more than 90 per cent of those in both groups were still alive, while almost 85 per cent in each were free of recurrence.
Researchers concluded that almost 70 per cent of women with this form of breast cancer could safely dodge chemotherapy.
The results represent an evolution in how this most common form of breast cancer will be treated in the future, agreed Dr. David Cescon, a breast medical oncologist and researcher at the Princess Margaret Cancer Centre.
“There have been other studies that have contributed, other supportive information along these lines, which have allowed us to avoid chemotherapy, particularly for women in the lower end of this middle-risk group,” he said.
“But this will allow us to make those recommendations with more confidence, particularly in the higher end of the middle range for older women.”
Dr. Andrea Eisen, an oncologist at Sunnybrook Health Sciences Centre in Toronto, said there has been an ongoing shift over the decades in how breast cancer is treated.
“Everybody used to have a mastectomy, then we realized doing a lumpectomy and radiation was essentially just as good,” she said.
“And then everybody used to have an ancillary lymph-node dissection, so removal of a lot of lymph nodes under the arm. And then we realized that a smaller operation called a sentinel node biopsy could give in most cases equivalent information.”