Genetic test may be able to predict need for chemotherapy in early-stage breast cancer

By Sally Robertson, B.Sc.Aug 25 2016

Patients with early stage breast cancer who have a low genetic risk of disease recurrence may not need to have chemotherapy, report researchers.

The findings come from a study that used a genetic test called MammaPrint to assess the risk of cancer recurrence in women with early-stage disease.

The genetic markers that tumors carry vary from individual to individual and MammaPrint works by checking a 70-gene signature that predicts the likelihood of disease recurrence among such patients.

As reported in the New England Journal of Medicine, Laura van’t Veer (San Francisco Helen Diller Family Comprehensive Cancer Center) and colleagues used MammaPrint to genetically profile excised tumors from almost 6,700 patients with early-stage breast cancer.

The results showed that women with a high clinical risk of recurrence, as determined by conventional measures such as tumor size and spread to lymph nodes, but a low genetic risk, as determined by MammaPrint, had very similar prognoses, whether they had received chemotherapy or not.

After five years, 94.7% of women with a high clinical risk, but low genetic risk were still alive even though they had not received chemotherapy. This survival rate was only 1.5% lower than that among women with the same clinical/genetic risk profile who had undergone chemotherapy.

All patients had received other standard therapies after their surgery including radiotherapy and hormone therapy.

The results indicate that clinicians could use MammaPrint to help them assess the best treatment option for these patients and to decide whether or not chemotherapy is necessary or not.

For the first time, a prospective, randomized trial shows that the active biology of breast cancer in an individual, as assessed by the MammaPrint test, can assist in making a well-informed choice to undergo chemotherapy treatment or not,”

Laura van’t Veer, Co-first author of the paper, director of Applied Genomics at UC San Francisco Helen Diller Family Comprehensive Cancer Center.

According to the World Health Organization, breast cancer is the most common cancer among women worldwide and is estimated by the American Cancer Society to have accounted for 25% of all new cancer cases in women internationally in 2012.