A new study aimed at finding the best way to treat early-stage breast cancer has revealed that ‘precision medicine’ doesn’t provide clear answers when it comes to selecting the best therapy patients should be offered or take up.
David Hunter, a professor of cancer prevention at Harvard’s T.H. Chan School of Public Health said that “precision doesn’t mean certainty”. This point is supported in the latest large study that was published in the New England Journal of Medicine. The study involves the decisions made with regards to chemotherapy for breast cancer patients.
Similar to other cancers, catching breast cancer at an early stage allows treatments to be more effective. The lead author of the study, Dr. Fatima Cardoso, says that this gives rise to confusion for patients and doctors. Dr. Cardoso, a breast cancer specialist at the Champalimaud Clinical Center in Lisbon, Portugal, said that a lot of times women receive chemotherapy even if the chances of their survival are low. She added that a lot of early breast cancer patients are over treated by doctors due to confusion still present in the field of breast cancer treatment.
Dr. Cardoso wanted to refine the treatment decisions and that’s why she aided in organizing a large study throughout Europe. She wanted to see if MammaPrint, a commercial genetic test, could serve a role in reducing the over treatment that women receive. More than 6,600 women took part in the research at 112 institutions and spanning nine nations.
In the study, women with breast cancer who were relatively at a high risk for having the cancer return after surgery, as suggested by their physical exams, but were at low risk of experiencing cancer again based on the results from MammaPrint, were identified by researchers.
The women were then invited to take part in a study in which they would be assigned to undergo chemotherapy. The women who would be assigned to go through chemotherapy were selected at random. “You know that chemotherapy is a treatment that scares people, so overall and for the majority of patients, it was not difficult to convince them,” Cardoso says.
The commercially available genetic test was effective at predicting the women at low risk of recurrence of breast cancer and thus, could avoid chemotherapy. A total of 70 distinct features of a tumor are studied by the test. It is priced at over $4,000 and some insurance companies in the U.S cover it.
The results of the studies revealed that a total of 46% women who were shown to be at high risk of cancer recurrence based on their physical symptoms didn’t suffer from drastic changes to their survival rate if chemotherapy treatment wasn’t provided to them. However, it was noted that the results weren’t definitive at all times. Approximately 95% women who didn’t get chemotherapy due to the results from the genetic test were shown to be free of metastasis after five years. But women who did get chemotherapy were able to do 1.5% better.
“It’s possible that the benefit is zero, and it’s possible that’s 2 percent or maybe even a little more, you can’t be sure,” said Dr. Clifford Hudis, chief executive officer of the American Society of Clinical Oncology. While he wasn’t involved in the study he did co-author the accompanying editorial. More research is required to see if a survival advantage is indeed possible due to chemotherapy for such women.
Dr. Cardoso said that she’s seeing a lot of women making decisions based on the results of her current study. She said that a majority of women who are at a low risk of breast cancer recurrence, due to the results from the genetic test, decided not to go through chemotherapy. However, there were also a small number of such women who still underwent such treatment as a 1% increase in survival rate held merit for them. She added that the new research and the information it has revealed does help breast cancer patients and doctors to make better decisions with regards to cancer treatment.