Women who have undergone treatment for hormone-receptor positive breast cancer typically take aromatase inhibitors for the subsequent five years. The study showed that extending this treatment to 10 years lowers the rate of recurrence. The added benefit of continuing aromatase inhibitors for 10 years as opposed to five must, however, be weighed against the side effects. For women who are at high risk of recurrence, the results of this study are of particular interest.
The story does a commendable job of presenting a clear and balanced report of the study findings, and by stating that the results did not find a difference in overall survival.
Continuing aromatase inhibitors beyond the standard five years is already a choice undertaken by some women and their doctors. This study is the first to rigorously address whether this is beneficial.
The story mentions costs. Letrozole, the aromatase inhibitor used in the trial, is available as a generic for less than $100 a month.
The benefit of continuing aromatase inhibitors for five additional years is presented clearly. The study shows that among hormone-receptor positive breast cancer survivors, the risk of recurrence is lower for women continuing aromatase compared to those who did not, particularly in the opposite breast. The story breaks down the figures by whether recurrence occurred in the original breast or in the opposite breast:
In a randomized controlled trial, 959 women were given the drug and 959 a placebo. Thirteen of the women taking the drug for an additional five years developed breast cancer in the opposite breast during the study, compared with 31 taking the placebo; 55 and 68, respectively, developed a recurrence of cancer in the original breast.
Later in the story, the overall recurrence rate is given.
95 percent of those taking letrozole for the additional five years remained free of breast cancer (meaning the disease had not returned in the original breast or developed in the opposite one). Of those taking an inert pill, or placebo, 91 percent did.
The story could have gone a step further by explaining more clearly what the recurrence rate for breast cancer is normally. The description of “200 to 1 odds per year” is not easy to understand and it’s unclear if the recurrence rate in the study was lower than expected in the general population.
First, we applaud the story for recognizing the difference between absolute and relative benefits.
But because the absolute benefits were not huge, and because the drug did cause side effects, it makes sense to consider this for women at the highest risk of a recurrence of breast cancer, he said.
The story also clearly understands that the absolute benefit of the treatment must be weighed against the side effects:
Aromatase inhibitors cause side effects in some women, especially night sweats, hot flashes, and sexual dysfunction. Women receiving five more years of letrozole also had greater loss of bone in their hip, worse osteoporosis, and more fractures.
One thing that would have made this even stronger: Including the rates of the different side effects.
The type of conclusions drawn by the story are supported by the design study being a randomized controlled trial. A strong grasp of the quality of the evidence is exhibited by recognizing these important caveats:
The study did not continue long enough to discover whether the lower risk of developing cancer in the opposite breast translated into a lower risk of death.
There was no difference in survival, however: 100 women in each group died during the study.
Dr. J. Leonard Lichtenfeld, deputy chief medical officer for the American Cancer Society cautioned, however, that “one has to be cautious in interpreting these results,” partly because “based on what they show, there is no overall change in survival.”
There is no disease mongering in terms of the overall risk of developing breast cancer or the risk of recurrence.
Kudos here, too. Dr. Richard Schilsky was interviewed as an independent source. Conflicts of interest were also disclosed: The study was funded by Novartis which sells letrozole, and several of the study authors are connected to pharmaceutical companies.
Continuing aromatase inhibitor was compared to not continuing it. There was a brief mention that study participants had taken another drug, tamoxifen, before starting letrozole. However, we’d have liked to have seen details on what other long-term alternatives women have for preventing recurrence.
The drug letrozole is already available, and the story makes this clear.
The story adequately establishes the novelty of the study:
“The reason this is a milestone trial is that it’s the first to show that 10 years [on letrozole] is better than five,” said Dr. Nicholas Robert, an oncologist with Virginia Cancer Specialists and a co-author of the study.
“…If you can tolerate the side effects, I think many women will opt to take the extra years of letrozole, so this study is practice-changing.”
This is important because many patients already continue aromatase inhibitors:
Experts said the study was significant because some women and their doctors choose to continue aromatase inhibitors past the standard five years. There had been no research on whether that was beneficial.
The story had interviews with independent sources and does not appear to be copied from a news release.