In this groundbreaking study results suggest that about 70% of patients diagnosed with common forms of early breast cancer can safely avoid chemotherapy thanks to testing. 21 gene testing examines patient’s biopsy samples to determine how active the tumors are, then the tumors are assigned recurrences scores from 1-100 with higher scores indicating greater chance the cancer will recur in distant organs and decrease survival. Typically there is decreased risk of recurrence in patients with higher scores who receive chemotherapy.
Mid ranged scores pose challenges, as it was previously uncertain whether chemotherapy was great enough to justify added risks and toxicity. It has been previously demonstrated that low score of 10 or lower did not need chemotherapy, high scores above 25 did require chemotherapy. This study was designed to examine breast cancer patients with gene test scores that fall into the mid range of 11 to 25.
10,273 women were enrolled to participate in this study with hormone-receptor positive, HER-2 negative breast cancer that had not spread to the lymph nodes, 69% of patients had intermediate score on the 21 gene test; researchers examined outcomes of the 69%.
At random participants were assigned to receive either hormone therapy alone, or chemotherapy followed by hormonal therapy; groups were examined for outcomes which included having cancer recur locally, having cancer recur to distant sites in the body, overall survival, and being cancer free.
Entire study population with gene test scores that were between 11-25 and especially among participants aged 50-75 there was no significant difference between the two groups. Among participants younger than 50 outcomes were similar to when gene test scores were 15 or lower. Among younger participants with gene test scores of 16-25 outcomes were slightly better in the chemotherapy group.
Researchers say this study should have impacts as findings will greatly expand the numbers of patients who can safely forgo chemotherapy without compromising their outcomes, and advance the steps to de-escalate toxic therapies.
