Increasing the dose intensity of chemotherapy lowers breast cancer recurrence

Increasing the dose intensity of chemotherapy by shortening the time period between treatments may help to reduce the risk of breast cancer recurring, a new study shows.

The research, presented at the San Antonio Breast Cancer Symposium, also noted that delivering drugs sequentially rather than at the same time helped to reduce the risk of recurrence and death.

The study involved a meta-analysis of a number of clinical trials comparing treatments in which chemotherapy was given every two weeks instead of every three weeks, and others in which anthracycline and taxane-based chemotherapies were infused sequentially rather than concurrently as is usual practice.  

Lead researcher, Dr Richard Gray from the University of Oxford, says giving chemotherapy more frequently increases the average weekly dose so that it is 1.5 times higher than with the standard three-week regimen.

“Another way of increasing the dose intensity of chemotherapy is to give the chemotherapeutics individually in sequence rather than administering all the drugs together at the same time.

“This sequential approach allows higher doses of the individual drugs to be used in each cycle while keeping the side effects manageable,” Dr Gray says.

The researchers say the results were marked. Compared with those on the standard regimens:

  • Patients who received chemotherapy every two weeks were 17 percent and 15 percent less likely to have disease recurrence and die from breast cancer within 10 years
  • Patients who received sequential chemotherapy were 14 percent and 13 percent less likely to have disease recurrence and die from breast cancer within 10 years.

“We were surprised by how strong and consistent the findings from our study were. 

“The results apply to most women receiving chemotherapy for early-stage breast cancer and the 15 percent reduction in recurrence with dose-intense chemotherapy across all trials was similar in ER-positive and in ER-negative disease, and did not differ significantly by any other patient or tumour characteristics, including age, HER2 status, nodal status, tumour size, and grade,” Dr Gray says.

He points out that there were few additional side-effects with the dose-intense schedule compared with standard schedule of chemotherapy.

“Some centres prefer giving chemotherapy every three weeks and offer treatment every two weeks less frequently because of concerns about side-effects and uncertainty about the additional benefit.

“But looking at the data from large numbers of women receiving dose-intense chemotherapy, we have found no evidence to justify these concerns, and the results show consistent benefit from the more intense treatments,” Dr Gray says.

A limitation of the study is that the chemotherapy used in the dose-intensification trials varied in the doses, the number of treatment cycles, and the agents used.

Dr Gray says although dose-intense chemotherapy is clearly more effective at eradicating cancers, it is difficult to recommend any one particular dose-intense chemotherapy regimen based on this study.

He says more research is needed.

“It is important to continue to find out whether or not there are worthwhile benefits from one treatment compared to another.”

06 March 2018

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