Cancer treatments that attack tumours based on their individual genetic traits — not their location in the body — far outperform traditional methods, extending survival for twice as many patients.
The precision medicine field of targeted therapy involves testing tumours for clues about their genetic mutations, and matching patients with new drugs designed to block cancer's growth on a molecular level.
Researchers began studying the impact of these therapies in 2007, after seeing the success of Gleevec (imatinib) — a breakthrough drug approved by US regulators in 2001, that showed huge success against chronic myeloid leukemia.
The results of the first and largest precision medicine trial to look at survival across a host of cancer types and many different targeted therapies were released at the recent American Society of Clinical Oncology meeting in Chicago, the world's largest annual cancer meeting.
The study, called IMPACT, enrolled 3,743 patients from 2007 to 2013.
All the patients had advanced cancers, or "end-stage disease," involving cancers of the gastrointestinal tract, breast, or lung. Melanoma and cancer of the female reproductive tract were also included, along with rarer types of cancer.
Those enrolled had typically tried at least four — and sometimes up to 16 — other treatments that failed to halt the growth of their cancer.
Patients who received molecular targeted therapies either got an investigational drug then being tested in a clinical trial, or an FDA-approved targeted therapy commercially approved for another indication.
After three years, 15 per cent of people treated with targeted cancer therapies were alive, compared to seven per cent in the non-targeted group.
After 10 years, six per cent of the targeted group was alive, compared to just one per cent in the other group.
On the whole, targeted therapies led to an average of four months of life without the cancer advancing, known as progression-free survival, and nine extra months of overall survival.
Those who were treated with traditional approaches lived just under three months without cancer growing, and 7.3 months longer overall.
Further research will improve the range of therapies available to cancer patients.
"When IMPACT first opened, we tested for no more than one to two genes.
“Now patients are being tested for hundreds of actionable genes, amplifications and mutations, as well as for immune markers," said lead investigator Apostolia Tsimberidou, and professor of investigational cancer therapeutics.
"Ideally, in the future, patients' tumour testing and cell-free DNA analysis will become the standard of care at the time of diagnosis, in hopes of making a difference for patients upfront, especially in those with hard-to-treat cancers."