Single-dose patients faced fewer side effects and clinic visits with no loss in outcomes
One infusion did the job of seven. A single dose of zoledronic acid worked about as well as the standard seven doses for many women with early-stage breast cancer, a Canadian-led trial found.
The team said the result could reshape care for roughly 30,000 Canadian patients a year and two million worldwide
Mark Clemons, an oncologist at the Ottawa Hospital who led the study, did not understate the findings, calling them "an absolute slam dunk."
The results affect care for about 30,000 Canadian patients a year and two million worldwide, he said.
CTV News reported that researchers ran the trial at several hospitals in Ontario and published it in NEJM Evidence.
They tested something simpler than a new drug or a stronger regimen: whether patients could safely receive far less treatment with a similar long-term effect.
The study followed 211 post-menopausal women with early-stage breast cancer, half on the recommended seven doses and half on a single infusion.
After five years, researchers found no meaningful difference in cancer recurrence, cancer spread or death between the two groups.
The single-dose patients, CTV News reported, had fewer side effects, fewer hospital visits and less disruption to their lives.
The practical payoff drives the case.
Clemons said patients can skip the cancer-centre visits "every six months for three years."
A single infusion means "less toxicity, less blood tests, and more time with" family.
Each infusion under the standard schedule carries a real burden, since patients need blood work before every dose and must travel repeatedly to cancer clinics, with side effects that can include fever, nausea, flu-like symptoms, kidney complications and, in rare cases, serious bone loss in the jaw.
The drug's long life in the body gave researchers their rationale.
Zoledronic acid, one of a class of medications known as bisphosphonates, strengthens bones and cuts the risk of cancer spread in post-menopausal women with breast cancer.
Studies from more than a decade ago found it reduced the risk of the cancer reaching the bones, leading to guidelines that recommend seven intravenous doses over three years.
"We knew a single infusion would stay in the body for 10 years, so it made no sense giving the drug every six months," Clemons said.
The trial fits a growing movement in oncology known as "de-escalation," in which researchers ask whether less treatment can match the same results while cutting toxicity.
Bishal Gyawali, a medical oncologist and associate professor at Queen's University in Kingston who was not involved in the study, said the field has long pulled the other way.
The field of oncology usually asks what more it can do for patients, but that is "flawed thinking," Gyawali said, since the aim is quality and length of life, not just shrinking tumours.
He said oncologists are realizing they are "probably over-treating patients."
Part of the "Common Sense Oncology" group, Gyawali said the evidence convinced him a single dose "should be enough for most" eligible patients.
Caution remains.
The findings are "not ready for the universal de-escalation in all patients with breast cancer," Harvard scientist Neelima Vidula, who reviewed the study, told CTV News in an email.
She said single-dose patients ran a slightly higher risk of osteoporosis and fracture, though those at lower risk of bone spread could weigh stopping after one dose with their doctors.
Guidelines have not changed, but agencies are watching.
"Clinical trials like this provides important real-world evidence that clinicians can apply in their care of patients," officials from Ontario Health (Cancer Care Ontario) wrote in a statement to CTV News, adding, "We are aware of this research and it is under discussion."
Charitable funding rather than the pharmaceutical industry backed the work, with support from the CURE Foundation, the Ottawa Hospital Research Institute and the Ottawa Hospital Foundation.
Ottawa's Beth Ciavaglia drew the single dose after surgery, chemotherapy and radiation. "I didn't want to take less," she told CTV News, but the one dose, rough as a severe flu, spared her years of appointments.
Seven years on, she is cancer-free.
Clemons came back to the lesson: "more isn't better," he said.
More treatment adds "no additional benefits" but heavy toxicity and cost for patients and families.
