Earlier OPTIMA results found some over-40s could skip chemotherapy
Breast Cancer Trials is opening the OPTIMA Pre-menopausal Extension study this month at sites in Australia and New Zealand for pre-menopausal women aged 35 to 54 with breast cancer.
The extension builds on earlier OPTIMA results that found many people aged 40 and over could safely avoid chemotherapy when genomic testing showed low risk.
The new study will test whether younger women can also avoid chemotherapy when the Prosigna test shows a low genomic risk score and modern hormone-blocking therapies are used.
Chemotherapy is generally offered to people with early-stage disease that has spread to nearby lymph nodes because it lowers the risk of the cancer returning on average. However, Breast Cancer Trials says many people with hormone-receptor positive breast cancer get little or no benefit while still facing significant side effects.
That question is especially important for younger patients because chemotherapy in young women can cause permanent ovarian failure and infertility.
Prosigna test guides treatment decisions
The OPTIMA Pre-menopausal Extension study builds on the original OPTIMA trial, run by Breast Cancer Trials in Australia and New Zealand. OPTIMA recruited women and men aged 40 or older after surgery for newly diagnosed hormone-receptor positive breast cancer.
Its findings indicated that people whose tumours had a low genomic test score could be treated safely with hormone-blocking therapy alone and still achieve the same or better outcomes, without increasing the risk of the cancer returning.
The new study lowers the minimum age for participants to 35. It will use the same genomic test, Prosigna, which measures the activity of genes involved in breast cancer growth and provides a genomic risk score.
A/Prof Belinda Kiely, Breast Cancer Trials’ study chair, said many people receive chemotherapy unnecessarily and that the side effects can be particularly hard on younger women.
“In the future, I would like to see all women with hormone receptor positive breast cancer being offered one of these tests when they’re diagnosed, so they can get that information early on to help with their decision-making and planning,” Kiely said.
“For many younger women diagnosed with breast cancer, treatment decisions can have lifelong consequences — including impacts on fertility and quality of life,” Price said.
One former participant, Samantha Phillips, joined the original OPTIMA trial after she was diagnosed with ER+/PR+ HER2- breast carcinoma in 2024 at age 46. Her partner noticed an indentation in her breast while she was balancing a busy career as a CEO and family life.
Phillips was randomised to the treatment arm that avoided chemotherapy. She later had two surgeries and radiotherapy, and she continues on hormone-blocking therapy.
“For me, knowing the results of the genomic test through the OPTIMA trial meant I was able to get on with life as I knew it – without having to quit my job or pause my career,” Phillips said.
Founded in 1978, Breast Cancer Trials runs a multicentre national and international clinical trials research program into the treatment and prevention of breast cancer. More than 1,000 researchers across 118 institutions in Australia and New Zealand are part of the organisation.
