Some 70 per cent of women with early-stage breast cancer and an intermediate risk of cancer recurrence can safely skip chemotherapy after their tumors have been removed, US researchers said on Sunday.
"This is a major finding," said Dr Larry Norton, a breast cancer expert at Memorial Sloan Kettering Cancer Centre in New York, who more than a decade ago helped organise the government-funded study.
“It means that maybe 100,000 women in the US alone do not require chemotherapy,” Dr Norton said.
The research, presented at the American Society of Clinical Oncology meeting in Chicago, studied how to treat women with early-stage breast cancer that responds to hormone therapy.
Women were deemed to have a medium-level risk of the cancer coming back based on a 21-gene panel known as Oncotype DX from Genomic Health. The test predicts the likelihood of cancer recurrence within 10 years.
Those who score low on the test – which involves a scale from zero to 10 – are already told to skip chemotherapy after their tumors are removed and they receive hormone therapy. Those who score high – 26 to 100 – receive both hormone therapy and chemotherapy.
Method
The study, dubbed TAILORx, was also published in the New England Journal of Medicine. It involved more than 10,000 women with breast cancer that had not spread to nearby lymph nodes and whose tumors tested negative for the HER2 gene.
Of those women, 6,711 scored in the intermediate range of 11-25, and were randomly assigned hormone therapy alone or hormone therapy plus chemotherapy.
The study found that all women over the age of 50 with this type of breast cancer could skip chemotherapy, a group that represented 85 per cent of the study’s population. In addition, women 50 and younger who scored between zero and 15 could be spared chemotherapy and its toxic side-effects.
However, chemotherapy did offer some benefit to women aged 50 and younger who had a cancer recurrence score of 16-25, researchers found.
Dr Steven Shak, chief scientific officer at Genomic Health, said about four in 10 women in the US with early-stage breast cancer are not tested for recurrence risk. He expects the study's results will change that practice. – Reuters