Reducing fat intake reduces death rates in some breast cancer patients

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Published: 16 Dec 2014
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Professor Rowan Chlebowski - Harbor-UCLA Medical Centre, Torrance, USA

Prof Chlebowski talks to ecancertv at SABCS 2014 about the results of the Women’s Intervention Nutrition Study (WINS) which looked at nutrition and breast cancer.

Read the news story or watch the press conference for more. Also see comment from Prof Osborne for more.

You are the author of the Women’s Intervention Nutrition Study, a very interesting study where you actually tried to intervene with diet among women who had breast cancer. What did you do in fact?

Yes, these were 2,437 largely post-menopausal women with early stage resected breast cancer. Since they were recruited between ’94 and 2001 they received standard therapy, so hormone therapy for receptor positive, chemotherapy for receptor negative, appropriate radiation therapy but this is therapy from twenty years ago, but that standard therapy The randomisation was to a lifestyle intervention targeting dietary fat intake and we achieved that. We also got a 6lb weight loss which is both statistically significantly different than the control population. Intervention for five years had 24% fewer recurrences. Funding ended and so now after all these years, really it’s over a decade, we’re able to do a death registry follow-up.

Right, because it’s twenty years and you’ve now got what’s called the final survival analysis because some of your women sadly have died but you’ve got statistics on this now. What did you come up with exactly? You were giving me some of the numbers just there but in detail what did you have?

I should emphasise this is death registry follow-up so we’re really only able to find, unfortunately, the dead participants. But with that we look at overall survival, the overall population, there were 17% of the women had died in the control, 13.6% in the intervention but that difference was not statistically significant. However, in the oestrogen receptor negative population there was a 36% improvement in overall survival approaching two years of additional survival. And even more interesting and exciting from a biological standpoint in that oestrogen receptor negative progesterone receptor negative population we didn’t have HER2 status but SEER data registry will tell us that 73% of those patients would be triple negative so the population, largely triple negative, had a 54% improvement in overall survival, 2.3 years median survival increase.

It’s beginning, from what you say, to seem as if dietary intervention could be one of the arms of therapy?

Yes. This study which was negative overall but with these very, very interesting exploratory subgroup analyses really points to a need for confirming studies, perhaps especially in the oestrogen receptor negative population. In triple negative we’ve really been stuck for about 10-15 years in terms of breakthrough therapies.

But you’ve got a survival advantage in the group overall?

No, not overall. Overall there were fewer deaths but that was not statistically significant. Now, one of the problems with these long-term survival things is people start to die of many other things and we couldn’t separate out cause of death in our analysis.

What then can you definitely say about reducing fat in the diet among your patients being treated for breast cancer?

Right now we’re in a situation where if this was an expensive new drug you would need for sure confirmatory studies before you could do anything because of the toxicity or the cost. Here we have a different situation, we have a signal for the scientists, for breast scientists, other breast scientists, to work out. But for a woman with breast cancer we know there are benefits from this modest 6lb weight loss. A huge epidemic of diabetes, this can be reduced, progression to diabetes reduced, by just doing this. So a woman can look at this and say, “I know there are benefits from doing this, maintaining my weight or reducing weight, other than breast cancer. And by the way it may keep me from dying of breast cancer as well which we can’t be sure of.” So I think it’s a reasonable thing to say, “Why don’t you go a little bit that extra quarter mile and try this intervention as the scientific details get worked out?”

And I’m tempted to ask if you’ve got a weight loss were you chasing the right culprit with fat? Should it perhaps have been better to chase calories?

Sure. This is the usual twenty year hindsight, right? When we designed the trial fat was the target and the studies at that time didn’t even want us to achieve weight loss because they thought it would muddy the waters but now after twenty years more consistent data for weight loss, weight maintenance, increased physical activity which we had no idea about before. So now the interventions that would be on-going would be weight loss, weight maintenance and increased physical activity. So if a woman wants to consider something that’s what she should consider and if she has another favoured way of getting to weight loss we don’t have any evidence to say that that would be worse.

You’ve got a lot of experience on the factors involved here so what are your prudent recommendations to doctors for treating their patients as far as diet is concerned and, of course, let’s face it, activity?

The observational data coupled with our results suggest that weight loss, weight maintenance can be important for overall health and “may reduce chance of dying of breast cancer.” Increased physical activity, there’s lots of observational study data that it may even reduce recurrence risk. There are a couple of smallish trials that are on-going, randomised trials, looking at weight loss, increased physical activity centrally mediated. That’s going to be the future in terms of instead of having this one on one contact with a centrally mediated telephone intervention, internet intervention, it should be more easily achievable and then the question is whether the physicians should maybe engage this but a woman can engage this herself in terms of saying, “This is helpful and by the way I’m in a higher risk category that might have additional benefits from doing these healthful things.”

So could you distill, in just a few seconds, your current recommendations then, in a couple of sentences, for women with early breast cancer? What should they be doing ideally?

So if they’re not obese maintain their weight which can be some issue with our therapies. If they’re overweight or obese target just a 5% weight loss, increase their physical activity to regular walking about three hours a week. That, it looks like in observational study plus with this trial result, suggests that will have other health benefits and may reduce a bad outcome from breast cancer.

And one thing I think you suggested is get yourself a dog?

Yes. The other approach that I had suggested at an international meeting was that, as opposed to some of our expensive new therapies, that every breast cancer diagnosed patient should be handed by oncologists a Labrador retriever puppy. By the time she was through with her adjuvant chemotherapy the dog would be available for walking. There’s great evidence that dog owners are more likely to achieve physical activity guidelines than non-dog owners. So that would be a reasonable thing. Acquisition costs $500, maintenance costs $1 a day for dog food – you can’t beat that compared to our new therapies.