As many as 70 per cent of women with the most common form of breast cancer may be able to skip chemotherapy, based on their score on a genetic test, researchers said Sunday.
Until now, women have faced a great deal of uncertainty about whether to add chemo to hormone therapy after a diagnosis with hormone-receptor positive, HER-2 negative breast cancer at an early stage before it has spread to the lymph nodes.
“With results of this groundbreaking study, we now can safely avoid chemotherapy in about 70 per cent of patients who are diagnosed with the most common form of breast cancer,” said co-author Kathy Albain, an oncologist at Loyola Medicine.
“For countless women and their doctors, the days of uncertainty are over.”
A 21-gene test called Oncotype Dx that has been around for years has helped guide some decisions. A high recurrence score, above 25, means chemo is necessary to ward off a recurrence while a low score, below 10, means it is not.
The current study involved more than 10,000 women and focused on those whose scores were in the middle range, from 11 to 25.
Patients, aged 18 to 75, were randomly assigned to receive chemotherapy followed by hormonal therapy or hormone therapy alone.
Then, researchers studied the outcomes, including whether or not cancer recurred, and overall survival.
“For the entire study population with gene test scores between 11 and 25 -- and especially among women aged 50 to 75 -- there was no significant difference between the chemotherapy and no chemotherapy groups,” said the findings, published in the New England Journal of Medicine.
Among women younger than 50, outcomes were similar when gene test scores were 15 or lower.
Among younger women with scores 16 to 25, outcomes were slightly better in the chemotherapy group.
The results, presented at the American Society of Clinical Oncology annual meeting in Chicago, “should have a huge impact on doctors and patients,” Albain said.
“We are de-escalating toxic therapy.”
According to first author Joseph Sparano of Montefiore Medical Center in Bronx, New York, “any woman with early stage breast cancer 75 or younger should have the test and discuss the results” with her doctor.