PodMed Double T is a weekly podcast from Texas Tech. In it, Elizabeth Tracey, director of electronic media for Johns Hopkins Medicine, and Rick Lange, MD, president of the Texas Tech University Health Sciences Center in El Paso, look at the top medical stories of the week. A transcript of the podcast is below the summary.
This week’s topics include fluids best for resuscitation, a blood test for eight cancers, managing chronic pain for disadvantaged folks, and varicose veins and other circulatory problems.
0:43 CancerSEEK, a blood test for cancer
1:44 For some of the cancers no screening test exists
2:44 Compared to a normal population
3:45 Specificity in a healthy population may not apply
4:33 Managing chronic pain in a disadvantaged population
5:33 Tough population with tailored CBT
6:33 Varicose veins and DVT
7:33 An association perhaps with common risk factors
8:22 Critically ill patients and fluid use
9:23 Helps kidneys but no difference in mortality
Elizabeth Tracey: Is there a problem with varicose veins?
Dr. Rick Lange: Is there a difference in outcome with different resuscitative fluids?
Elizabeth: Can we use a single blood test to screen for eight different types of cancer?
Rick: And improving pain management in the most disadvantaged individuals.
Elizabeth: That’s what we’re talking about this week on PodMed TT, your weekly look at the medical headlines from Texas Tech University Health Sciences Center in El Paso. I’m Elizabeth Tracey, a medical journalist at Johns Hopkins, and we’re posting this on March 2, 2018.
Rick: I’m Rick Lange, President of the Texas Tech University Health Sciences Center in El Paso and Dean of the Paul L. Foster School of Medicine.
Elizabeth: Rick, I think I’d like to start first this week with one of the ones that’s the oldest, at least, for me. That’s this test that I served up, something that was developed largely here at Johns Hopkins, but with some other folks around the country as well. I said, “Hey, can we take a single blood test and screen for eight different types of cancers?” That’s exactly what they did here. They took 1,005 patients with clinically detected cancers that had not yet metastasized in their bodies, and these were of different types: ovary, liver, stomach, pancreas, esophagus, colorectal cancer, lung, or breast. Some of those already have some screening tests. Some of those don’t.
They were able to take this blood test and amplify the DNA from the tumor, and they were able to positively identify folks who, in fact, did have these cancers in 70% if we took a look at all those cancer types in total. If we break them out and we say, “Hey, how good were they at different cancers?” They weren’t quite as good. Now one of the things I find compelling about this study is that for some of these cancers, especially pancreas and ovary, we don’t have a current screening test. However, I would also say that CancerSEEK, at least for me at this time, is not quite ready for prime time.
Rick: Elizabeth, so they looked at two things. You described one and that is the genetic material. The thought being that when cancer cells die, they emit this DNA into the bloodstream. It’s so minute that you normally can’t detect it, but if you amplify it, you can. The other thing they did was they combined that with different proteins that are known to be associated with different cancers. So what I found most fascinating was the analysis they did, looking at 16 different genes, eight or nine different proteins, and then if it suggested there was a cancer, they looked at an additional about 31 proteins to try to identify what the source was.
It wasn’t very good, for example, at detecting breast cancer, only about a third of those, but much better for ovarian and pancreatic cancer. The flip side is we know that they compared this to what was considered a normal population to see how specific it was. What you don’t want to do is say that somebody has cancer when they really don’t. Very early in its development, unlike the analysis using both proteins and genes, but as you suggest, not really ready for prime time.
Elizabeth: You referred, of course, to the specificity and by their calculation, only 7 of 812 healthy controls turned up to be positive. That’s a specificity of greater than 99%, so that’s pretty powerful. I said to you before we started to record that I interviewed the senior author of this paper, and one of my concerns is if we all are kind of tossing off potential cancer cells in our bloodstream, gosh, what happens if we start detecting those and do they start making people excruciatingly hyper-vigilant with regard to the possibility that there are always circulating potentially cancer cells in our bloodstreams?
Rick: You highlight one thing and that is the overdiagnosis. I’m going to get back to the specificity for just a second. You say, “Well, it’s 99%.” That’s in a healthy population, but we’re not all healthy. Many of us have chronic inflammatory diseases, and that specificity may not be as good. Furthermore, if you apply this to 200 million people that don’t have cancer and [get a] 1% false positive rate, that’s still 2 million people that you say may have cancer when they don’t. So I’d suggest that a 99% specificity isn’t quite good enough yet.
Elizabeth: Okay. There is no doubt we’re going to be hearing more about this because, of course, we’re all persuaded by the idea that so-called liquid biopsy or, in this case, liquid screening would be just a fantastic idea, able to avoid all kinds of invasive things and hopefully get this overdiagnosis potential under control. Why don’t we turn from here to something that’s really very much at the other end of the spectrum? You served it up as, “Well, can we take a disadvantaged population and help them in managing pain?” That’s in Annals of Internal Medicine.
Rick: Specifically I want to talk about chronic pain, pain that’s been around for at least 3 to 6 months. It affects about 116 million Americans, and it costs about $600 billion annually. We tend to use analgesics because it’s easy to prescribe pills, but we know that when we prescribe opioids, that’s had an unintended consequence. We’re trying to focus on non-pharmacologic methods of treating it, and we know that cognitive behavioral therapy can be effective. People that are most affected by chronic pain are oftentimes the elderly, low socioeconomic status, women, as well. What these investigators did was they took about 300 participants; about 40% were reading below the fifth-grade level. They had pain for about 15 years at six different sites, at least four different causes. This was a really, really tough group.
They tailored cognitive behavioral therapy or education to a fifth-grade level. They had these individuals meet in groups with leaders over the course of about 10 weeks. Individuals who participated had a marked improvement in their pain scores and more likely to have better function as well.
Elizabeth: Yay! Gosh, I am so happy that so many people are addressing this issue of chronic pain, which, of course, we’re increasingly concluding is not suitable for opioid treatment and secondly, something that’s tailored to your audience. My goodness, this seems like an idea whose time was yesterday.
Rick: The nice thing about this is the investigators tailored it to the patients, but then they had the patients even refine it a little bit further.
Elizabeth: Let’s talk about the cost. Was there anything about that in there?
Rick: They paid the patients a modest amount just for their travel. That was $20. Other than that, it was just the cost of having group therapy.
Elizabeth: Good news! We like that one. Let’s turn, then, back to one of mine and that’s the look at I said, “Wow! What’s the problem with varicose veins?” Well, of course, one problem is they’re not very attractive and a lot of people find them difficult because of that. So in this study taking a look at about 213,000 people with varicose veins compared to an equal number of controls, they retrospectively took a look at what were the consequences of having varicose veins. They excluded people who had had previous deep vein thrombosis, pulmonary embolism, or peripheral artery disease.
What they basically found was gosh, in fact, if you’re an adult with varicose veins, there was an increased risk of deep vein thrombosis. Although, for pulmonary embolism and peripheral arterial disease, they were less clear conclusions. I guess I’m a little bit concerned about this because varicose veins, of course, are extremely common. We see them much more often in people as they age and women post pregnancy, and I guess I’m a little worried about it.
Rick: This is one of those studies that suggests there may be an association. It may be they have the same common risk factors. For example, we know that obesity is common among all of these. Furthermore, as you suggest, the association with DVT was pretty good, but with the other two diseases was really kind of modest.
Elizabeth: But does it suggest to you that if you have varicose veins maybe you ought to be a little more concerned or vigilant about the possibility of developing these other conditions?
Rick: Things that cause varicose veins, for example, sometimes sedentary lifestyle, obesity, predisposed to these other things as well. In as much as I’d be concerned about anybody with risk factors, the risk factors for varicose veins are the same risk factors, in many cases, as these other conditions.
Elizabeth: Let’s turn, then, back to you, taking a look at critically ill patients versus not critically ill patients and fluid, shall we call it, “restitution” in those folks. That’s in the New England Journal of Medicine.
Rick: Using fluids to resuscitate patients is very common, and we have a number of different fluids we can use. Normal saline is the one that’s frequently used. It really doesn’t approach the normal physiologic components of our blood. Conversely, we have things called balance crystalloids, things like lactated ringers and Plasma-Lyte that our surgeons have used for a long period of time.
There’s been some concern that the normal saline that has the high chloride content actually contributes to some kidney dysfunction. What this single center did was they took everybody who came into the emergency department, all who received resuscitative fluids were randomized either to normal saline or to lactated ringers or to Plasma-Lyte, and they followed them for a period of about a month. There were over 25,000 patients. The patients that received normal saline were more likely to have an adverse outcome with respect to their kidneys. They also looked at mortality. There was no real difference between the two. This suggests that resuscitative fluids may be better overall in critically ill or even non-critically ill patients compared to normal saline.
Elizabeth: Right now, of course, we’ve been having this nationwide shortage of saline. I’m wondering about the availability of this stuff and what’s going to end up happening if, in fact, this study gets borne out in larger studies.
Rick: Lactated ringers has not been affected by the shortage right now. The nice thing is the difference between the two is relatively modest, but it does appear that lactated ringers or Plasma-Lyte is somewhat better. The other thing I want to ask about is what’s the cost? They’re both about the same cost.
Elizabeth: Let’s hope it stays that way since we see lots of people who take these kinds of studies and turn them into opportunities to develop generics, create shortages, and increase prices.
Rick: These resuscitative fluids have been around for decades, and I don’t see anybody taking advantage of that. Although, you’re right. That happens frequently.
Elizabeth: That cynicism, I’m afraid, is coming out, so on that note, I will talk about the CancerSEEK, the test for the different types of cancer in the blood, this week on the blog. That’s a look at this week’s medical headlines from Texas Tech. I’m Elizabeth Tracey.
Rick: I’m Rick Lange. Y’all listen up and make healthy choices.