4 June 2018
CHICAGO: About 70 per cent of women with early-stage breast cancer and an intermediate risk of cancer recurrence can safely skip chemotherapy after their tumours have been removed, US researchers say.
“This is a major finding,” said Larry Norton, a breast cancer expert at Memorial Sloan Kettering Cancer Centre in New York, who helped organise the government-funded study more than a decade ago.
“It means that maybe 100,000 women in the United States 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 returning 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 — from 0 to 10 — are already told to skip chemotherapy after their tumours are removed and they receive hormone therapy. Those who score high — 26 to 100 — receive both hormone
therapy and chemotherapy.
The study, published in The New England Journal of Medicine, involved more than 10,000 women with breast cancer that had not spread to nearby lymph nodes and whose tumours responded to hormone therapy and tested negative for the HER2 gene. Of those, 6711 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 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 0 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. Steven Shak, chief scientific officer at Genomic Health, said about four in 10 women in the US with early-stage breast cancers were not tested for recurrence risk. He expected the study’s results to change that practice.
“This is going to provide the highest level of evidence now for our test being indispensable in clinical practice,” Dr Shak said.