Interview
with Neil Love, MD Breast Cancer Update for Medical Oncologists,
Program 6 2000
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Audio Below:
We’ve
now got really good evidence that five years of tamoxifen is better
than two years of tamoxifen. It’s not a big difference, but
it’s a real difference. We got 20,000 women randomized. 10,000
of them got about five years, 10,000 got about two years. But we
can now see that there is a small, but real, difference with five
years of tamoxifen being better than just two years of tamoxifen.
We don’t have comparable data in terms of whether ten years
is better than five years. There’s a fair number — a few
thousand women — who’ve been randomized, but they’ve
been randomized so recently, most of them, that we’ve hardly
got any follow-up on them. In terms of recurrences, we’ve got
a few hundred recurrences, whereas in the trials of five years versus
two years, we’ve got a few thousand recurrences. So, we don’t
have reliable information on whether ten years is better than five
years. And even worse, the recurrences that we do have, nearly all
of them in the first few years after randomization, where the carryover
benefit from that first five years is still going to be providing
a lot of protection in the control group. The real question is,
"Breast cancer is a disease with at least a 20-year natural history.
Would 10 years of tamoxifen be better than five years of tamoxifen
in terms of providing protection against recurrence in the second
decade after diagnosis?" And if you’ve got a woman aged 50
and a woman aged 60, the question is, "What’s going to happen
in terms of 20-year outcome?" And there’s almost as many breast
cancer deaths in the second decade after diagnosis as in the first
decade after diagnosis. We’ve really got to think on a long
time scale. When you do that, then the idea that ten years might
be better than five years actually becomes quite interesting. But
you’ve got to be saying, "Is 10 years better than five years
in terms of what it’s doing to breast cancer recurrences, the
breast cancer deaths in that second decade after diagnosis?" We’ve
got virtually no information in that second decade. And there’s
just a few dozen recurrences, which slightly favor longer treatment.
The
idea that there might be some serious adverse effect on breast cancer
from carrying on longer, I think, has disappeared. That, in retrospect,
was just a chance fluctuation, a zig in one trial, which has been
counterbalanced by zags elsewhere. Now it’s just averaged out.
So, I don’t think there’s any reason to fear that longer
treatment — 10 years of treatment — is going to be any
worse in terms of having an adverse affect on breast cancer itself.
But whether it’s going to actually have any worthwhile benefit
in that second decade, I think, is still unanswered.
