Genetic Map of Certain Cancers Discovered; Cancer Rate Drops

SUSAN DENTZER: These scientists actually showed that that strategy underlying the Cancer Genome Atlas could work.

They took 11 different breast cancer tumors and 11 different colon cancer tumors. These are tumors that, collectively, represent about one of every five cancer diagnoses a year in the country. So, it's a significant spread of cancer.

JEFFREY BROWN: That's why they chose those two cancers?

SUSAN DENTZER: That's why they chose those, yes, and those particular subtypes of cancers in those tumors.

They looked at those. They performed a very, very high-tech screening process, in effect, and essentially found, at the end of that process, that there were almost 200, 189, genetic mutations, most of which were previously unknown, that actually were contributing, if not in fact causing those cancers.

So, it's almost a way of saying they came up with a little tiny paragraph in this long catalogue that will ultimately be developed. But they showed that, in fact, through this process, you really can come up with meaningful discoveries.

And, in fact, one researcher described these as a treasure trove, in and of themselves, with respect to these two different types of cancer.

JEFFREY BROWN: So, the way for the rest of us to think about this, maybe, is that it's a strategy for how to develop what?

SUSAN DENTZER: It's -- in the end, it will be a strategy for developing very sophisticated, so-called targeted therapies, that actually look at the actual genetic changes that lead to a cancer.

What we have now to fight cancer, once we have diagnosed it, are very blunt instruments. We have chemotherapy. We have radiation. They come in, irrespective of what is causing your cancer genetically, and they wipe out lots of cells, including the cancer cells.

So, they're very blunt instruments. What the future holds, and what we see now in certain drugs, like the breast cancer drug Herceptin, is a drug that is specifically matched to the set of genetic changes that happen that trigger a particular subtype of cancer.

We know that there are many, many different types of breast cancer. If we could figure out specific, targeted therapies, something that gets in, that either switches a gene on or off, blocks a protein that a mutated gene might contribute to the body, whatever, we will be able to come up with things which will be much more effective, probably much less toxic to individuals than chemotherapy or other things are.

Now, it's important to say, these things are not going to be flying off the shelf tomorrow.

JEFFREY BROWN: Right. That was the next question.

SUSAN DENTZER: This is a long, long process.

JEFFREY BROWN: I mean, this is -- as you said, this is just part of mapping this atlas. So, that's...

SUSAN DENTZER: Right.

JEFFREY BROWN: ... where the research continues?

SUSAN DENTZER: That's right.

And then, of course, we have a long path ahead of us, in terms of developing these therapies, testing them for their safety, etcetera. But what it tells you is that, over the next 20 and 30 years, the strategy for fighting cancers is going to change remarkably, both in terms of preventing them and getting them very early on in the process, and, in effect, treating them very effectively.

So, the second bit of news involves data from what's happening in the last few years. Let's just look at a snapshot of right now. Generally speaking, cancer rates are on the decline, continuing to decline, correct?

SUSAN DENTZER: Cancer death rates.

JEFFREY BROWN: OK.

SUSAN DENTZER: And, of course, that's the gold standard.

JEFFREY BROWN: Right.

SUSAN DENTZER: That really shows that progress has been made against fighting cancer, if you have fewer people dying. And, in effect, the rates...

JEFFREY BROWN: Death rates, as opposed to incidence?

SUSAN DENTZER: Incidence, that is to say, new diagnoses of new cancers.

JEFFREY BROWN: OK.

SUSAN DENTZER: And, in fact, cancer death rates overall have been declining since the 1990s. And the trend is being perpetuated into the present, across the board in the major cancers that affect both men and women, and across all races. So, that's very good news.

One of the big drivers of that, for example, is lung cancer declining in men, because fewer and fewer men are smoking. So, those are important trends.

The other trend, though, is the one you alluded to, which is incidence, that is to say, new diagnoses of cancers. And, across the board, we're seeing many of those rates stabilize, or, in some cases, drop.

Now, it's not everything.

JEFFREY BROWN: Right.

SUSAN DENTZER: For women, for example, incidence of melanoma is going up; incidence of lung cancer is going up. So, again, it's not universal.

But the big one that people were getting quite excited about was that new diagnoses of breast cancers seem...

JEFFREY BROWN: Right.

SUSAN DENTZER: ... to be leveling off. And that's important, because those rates were climbing in the 1980s, and giving people a lot of concern.

If we get more evidence in future years that those rates are continuing to stabilize, or even decline, that will be very good news, indeed.

SUSAN DENTZER: Right. You really want to see several years of data cropping up, showing the same thing.

And, also, frankly, there are other things in the environment, we know, which could drive things the other way.

We know that rates of obesity among adult women are rising. Obesity is correlated and linked to breast cancer rates. So, we can't pop the champagne bottle yet. We will have to see how these trends play out over time. But, at least for now, there's some sense that the rates -- that new diagnoses are stabilizing.

JEFFREY BROWN: Yes.

And is there any thinking on why that is happening?

SUSAN DENTZER: Very speculative at this point, but one of the points of speculation, for example, is that hormone therapy use among women dropped off sharply once, in 2002, it was reported, the major federal study reported, that there were higher breast cancer risks attendant using hormone therapy.

A lot of women went off it at that point. It could be that we're beginning to see some signs, in terms of the cancer diagnoses, that that trend in fact played out.

But, again, it's speculative. And, really, it will take several more years of data to find out what really happened.

JEFFREY BROWN: All right, Susan Dentzer, thanks again.

SUSAN DENTZER: Thanks, Jeff.