SATURDAY, June 4, 2011 (HealthDay News) -- For patients undergoing surgery for colorectal cancer, a new study suggests that the sooner chemotherapy starts following the operation, the better the prognosis.
For every month after the first four weeks post-surgery that chemotherapy is delayed, odds of survival decrease measurably, the Canadian researchers found.
"What our research has indicated is that giving chemo early rather than later after surgery is associated with improved survival," said study lead author Dr. James J. Biagi, a medical oncologist and head of the oncology department at Queens University, in Kingston, Ontario. "Giving it later appears to be detrimental."
"But at the same time, we also believe that it still might be worthwhile having a patient look to chemotherapy even if they wouldn't be starting until the three-month point," Biagi added. Traditionally, oncologists avoided recommending chemo after that benchmark.
Biagi and his colleagues are slated to present their findings Saturday in Chicago at the American Society of Clinical Oncology annual meeting, and the study will appear in the June 8 issue of the Journal of the American Medical Association.
In Western countries, colorectal cancer is the number three cause of cancer fatalities, the authors said.
Surgery to remove cancerous tissue is usually the first line of treatment for patients diagnosed with stage 1, II, or III colorectal cancer, followed by chemotherapy to eradicate any remaining disease. The ideal time frame for beginning chemo remains unclear, however.
To examine the question, the authors systematically reviewed and did a meta-analysis of data from 10 different studies conducted between 1975 and 2011. (A meta-analysis statistically combines the results of different studies with related hypotheses.) In total, the investigations involved more than 15,400 patients.
"What we found is that roughly for every month delayed, chemotherapy is 14 percent less effective in improving survival rate," noted Biagi. "That's relative to giving it within four weeks after surgery, which is the anchor time point we compare it to."
This means that for a patient who is ready for chemotherapy at the four-week post-surgery mark (a patient with no health complications that might require chemo postponement), waiting until the eight-week mark increases the risk of death by 14 percent.
If the same patient were to experience a delay in chemotherapy treatment until the 12-week post-surgery mark, the risk of death would increase to 30 percent, the authors said.
With respect to the value of beginning chemo at or after three-months post-surgery, Biagi and his colleagues referenced the standard assumption that the five-year survival rate post-surgery without chemotherapy is about 45 percent. With chemo delivered at a 12-week post-surgery window, this rate typically rises to about 60 percent.
The current study found that delaying chemo until the 12-week mark reduces five-year survival rates to 48 percent. The team therefore concluded that promoting the treatment as a viable option as late as four to five months post-surgery might have merit.
"We still don't know the ideal time to begin chemotherapy," Biagi said. "We were not able to pinpoint that. But certainly all things being equal, earlier appears to be better than later."
"The message is that we should be trying to avoid unnecessary delays when providing chemotherapy," he added. "Not all patients are ready to start chemo right away for all sorts of reasons. But for those who are, we're simply saying that we should focus on improving the efficiency of patient flow through the health care system from surgery to chemotherapy."
The researchers also noted some study limitations, including that another chemotherapy drug is now in use and that the studies relied on retrospective data.
Dr. Frank A. Sinicrope, a professor of medicine and oncology at the Mayo Clinic in Rochester, Minn., approached the issue of chemotherapy timing with caution.
"The big question has always been, how long can we wait?" he noted. "And, of course, we generally like people to have a period of recovery. But for many patients how long that is is really dependent on the patient's overall condition."
While conceding there could be a reduction in benefit the longer the delay, Sinicrope said much more research -- "with very large numbers of patients and very robust data" -- is needed to validate the findings.
More information
For more on colorectal cancer and chemotherapy, visit the American Cancer Society.
