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TORONTO (CP) - Women with early-stage breast cancer can safely wait up to three months after surgery to begin chemotherapy, but delaying treatment beyond that point increases the risk of recurrence and death, a large Canadian study concludes.
In an analysis of health records from almost 2,600 women with breast cancer, researchers from the B.C. Cancer Agency found that women given chemotherapy within three months of tumour removal did much better than those whose chemo was delayed.
Five years after diagnosis, recurrence and overall survival were similar among women starting chemotherapy any time within a three-month window following surgery. But the risk of recurrence increased and survival was dramatically reduced among those who waited longer, either by choice or by force of circumstance.
"Time matters, but not in as short a time interval as we think, so patients can be reassured if they're feeling anxiety because they don't feel their treatment is starting fast enough," said lead investigator Dr. Caroline Lohrisch, a medical oncologist with the B.C. Cancer Agency.
"Or if they're feeling anxious, on the flip side, because all these decisions are coming at them so fast and they need time to digest it, then it's safe to take a bit of time before they start their treatment," Lohrisch said Monday from Vancouver.
The study, published online in the Journal of Clinical Oncology, showed that delaying chemo past three months had grave consequences for some women: among those who initiated drug therapy at 12 to 24 weeks, 31 per cent had their cancer return - compared with 18 to 26 per cent of women who began chemo at an earlier point.
Five-year survival was also affected by timing of chemo: among women who started within four weeks of surgery, 84 per cent were alive five years after diagnosis. Similar rates were recorded for women who began their drug treatment four to eight weeks (85 per cent) and eight to 12 weeks ( 89 per cent) after surgery.
But among women who didn't start chemo until more than 12 weeks post-surgery, the survival rate dropped to 78 per cent, determined the researchers, whose study included patients diagnosed between 1989 and 1998.
Looked at another way, although there were deaths in each group, more women died from breast cancer if the interval between surgery and chemo exceeded three months. For example, 15 per cent of those who started drug therapy at four to eight weeks died, compared to 21.5 per cent of those in the three-month-plus group.
"If you take 100 women, that's a difference of 21 versus 15, that is seven lives," said Lohrisch. "If you take 10,000 women or 100,000 women, it translates into a big number."
Dr. Mark Clemons, head of breast medical oncology at Princess Margaret Hospital in Toronto, called the research a "nice, solid paper" that should help reassure Canadian women.
"This is an important study because delay in commencement of any cancer therapy is extremely scary for patients, who are understandably worried that any delay might lead to a worsening of their prognosis," Clemons said.
"It's also important from a physician and a health-care system point of view that we set targets and goals to make sure that we're treating patients within appropriate time frames."
While there is no official guideline that tells doctors the optimal period after surgery to begin chemotherapy, Lohrisch said most patients probably start the medication regimen within four to eight weeks.
Many factors can delay that first infusion, however. It may take some women longer to recover from surgery; pathologists who analyze tumours may be backed up due to workload; and wait times to see an oncologist may be lengthier in some areas of Canada than others, particularly in rural or remote areas.
"It's OK to take a bit of time if people need a bit of time or if the system is such that that time (delay) happens, but there is a time limit both for patients to consider and for physicians to strive to meet to maximize the outcomes," Lohrisch said.
"So a surgeon shouldn't delay in referring too long and a medical oncologist shouldn't defer in seeing the patient and starting the treatment. But the kind of usual delays are probably safe."
The B.C. researchers say their results should help relieve women newly diagnosed with breast cancer that they can take some time before starting chemo to gather information and be involved in decisions about their treatment - steps that have been shown to reduce anxiety and depression associated with the disease.
An estimated 22,300 Canadians will be diagnosed with breast cancer this years, says the Canadian Cancer Society. About 5,300 will die of the disease.
Early diagnosis and reasonably prompt treatment offer the highest hopes for beating breast cancer, doctors agree.
"The best success is when you have the smallest amount of disease to deal with, so the sooner you start (chemotherapy), the smaller the amount of disease you have to deal with," said Lohrisch. "And it seems from this study, anyway, that once you hit the three-month mark, that's the place you need to worry about the amount of disease becoming insurmountable, or less surmountable."
© The Canadian Press, 2006
