Alan Cassels, author of 'Seeking Sickness' on the disease screening industry, what it really catches, when to say no, and more.
Certain widely promoted screening procedures have been shown to do more harm than good.
- Seeking Sickness
- Alan Cassels
- Greystone Books (2012)
As a critic of the pharmaceutical industry, Alan Cassels has written extensively about the interest drug companies have in developing a market for their products by broadening the definition of disease. In his latest book, Seeking Sickness (Greystone Books, $18.95), he turns his attention to medical screening and what he characterizes as the "misguided hunt for disease."
In 11 chapters, several of which were developed as part of a Tyee series, Cassels looks at tests that are commonly given to healthy people, including screens for prostate cancer, breast cancer, osteoporosis and high cholesterol. Though the tests are offered by health professionals and promoted by advocacy groups, there is often little evidence they actually extend lives and in some cases they are likely to lead to more harm than good, he found.
The Tyee recently interviewed Cassels in his downtown University of Victoria office about his recent work. Following is an edited version of that conversation.
The Tyee: How did you get interested in screening?
Alan Cassels: Probably when I started seeing ads for full body scans, including this ad that fell out of the Times Colonist about five years ago that said a full body scan can save your life.
Tyee: Can't it?
Cassels: I was very curious. When someone's offering to save your life, you kind of take notice. I took it and showed it to a few colleagues. It's a private company in Port Angeles marketing full body scans to Canadians. We wrote a grant proposal, got some money from the Office of Consumer Affairs with Industry Canada and we spent a year interviewing people, studying the regulations and discovering the consumer is naked in the screening market place. There's no one really protecting people from being exposed to screening that is neither recommended, didn't have scientific support, that had evidence of harm in terms of exposure to radiation and good evidence that kind of screening causes huge amounts of follow up in the average person. They're marketed as providing peace of mind, when they are statistically more likely to do the opposite, which is to give you a bunch of things you now have to worry about that you never knew you had to worry about before.
Tyee: That's for full-body scans in particular, but other screens do save lives, right?
Cassels: The full-body scan you can write off as being the extreme end of the commercial side of screening, but what about other kinds of screens? I began thinking if there's no scientific support for a full-body scan, what is there for other kinds of screening that are really popular, recommended and supported by physician groups and patient groups? I started looking to things like mammography and Prostate Specific Antigen testing. There was a lot of kind of similarities in that the gap between what the evidence said and the marketing said was sometimes quite large.
Tyee: I have several friends and family members who are undergoing, or who have undergone, treatment for prostate cancer. Reading your book I have the impression you think they've been duped. Have they?
Cassels: I don't know if they've been duped. I think a lot of men have gone into screening only being told of the positive and made to be highly fearful of the consequences. There's pretty good evidence that the information that men have been given in the past about prostate screening was overwhelmingly positive, saying "you should do this, this could save your life, do it for your family," and I think didn't really capture the potential downside of it.
Prostate and mammography screening are well studied. You actually have good evidence so you can say statistically your likelihood of having your life saved by prostate cancer screening or by mammography When you look at the evidence on prostate screening, it's true that it finds a lot of prostate cancer. The question people need to ask though is, "Is finding all this prostate cancer going to lead to an overall reduction in prostate cancer deaths?" It's one thing to capture and discover a lot of cancers, but if they are cancers that are not going to go on and hurt you, then you're likely to be committing overdiagnoses.
Tyee: Is prostate screening leading to a reduction in deaths?
Cassels: I think this report from the United States Preventive Services Task Force says overwhelmingly not, it doesn't. If you have large groups of men who are screened, and compare them to large groups of men who are similar in age and family history and are not screened, the screened group on average is not going to live longer than the unscreened group.
Tyee: Does that mean nobody should get a PSA test?
Cassels: No. I think doctors will say it depends on your risk. If you've got a family history of this, for example, you might be someone who would more likely benefit from having a PSA screen than someone who doesn't have a family history of it. Certainly with breast cancer they recommend if you have a mother or sister that had breast cancer, statistically your chances of having it are a little bit higher. Whenever your risk is higher, your likelihood of benefit is higher. For those people it might make sense.
Tyee: Have there not been studies that support the use of the PSA?
Cassels: When they look at the same end points, they will come to the same conclusion as the USPSTF. If they look at different end points, they'll come to different conclusions. For example, they may say prostate cancer screening improves survival time, as opposed to improving survival, meaning the time you survive after they've diagnosed you with the disease. If you're tied to the railway track, and the train's coming down the track and it's going to hit you at a particular time, you can see it maybe without binoculars at five miles, say a five year survival rate. Or, if you use the screening test, binoculars, you can see it at seven miles. Your survival time has improved. The date at which the train hits you does not change, but the statistics look like the survival time has improved by two years.
Tyee: Doesn't that give you two more years to get out of the way of the train?
Cassels: Or two more years to worry about it, yeah.
Tyee: Does nobody get out of the way of the train in those extra two years?
Cassels: The research has to be looking at the same things. If you're looking at just survival, do the people who've been screened live longer? In the big studies with thousands of men in these screening programs, they don't see any difference. That's not to say some individual men might benefit, but on average they're not going to live any longer.
Tyee: You cite some 2 million men diagnosed with prostate cancer in the United States. Do the numbers translate to Canada?
Cassels: Not directly. For asymptomatic men in British Columbia, the government won't cover your PSA test. I think when the government refuses to pay, that's a really strong signal. Good governments will not pay for the things that are likely to cause harm and produce no benefit. I think making the decision between medically necessary, important and frill is a good thing for governments to do.
Tyee: So as a patient in B.C. then, can I assume any screen the government's willing to pay for is worth having and any screen they're not willing to pay for I probably don't need?
Cassels: It's a good sign, but it's not foolproof. I'll give you an example. The government pays for bone densitometry, I believe, which has absolutely skyrocketed in the last 10 years. In 1995 there was virtually no bone density testing of healthy, well women in British Columbia. Now, the government probably subsidizes several hundred thousand bone density tests a year as a screen for osteoporosis. If I was the government I wouldn't do that.
Tyee: Why not?
Cassels: The thing is, before you get the screening test you have to ask yourself, if I would do the same thing whether the test were positive or negative, the principle should be don't do the test. You have people who might be told they have osteoporosis or don't have osteoporosis, the recommendations are going to be the same. Weight bearing exercise, calcium, vitamin D. The test didn't add anything except the label and maybe the reason to start taking a drug.
Tyee: But might it not be a wake-up call for some people to do those things?
Cassels: I can't discount that. For some people getting a wake-up call might be useful.
Tyee: So as a patient, what should I be asking before undergoing a screen?
Cassels: I have a list of questions in the book. The key one is what have the independent experts said about the value of the screening. The United States Preventive Services Task Force is one of them. The Canadian Task Force on Preventive Health Care, that's the Canadian equivalent. Most of the stuff you see about prevention is biased. For every one site like this funded by the taxpayer with largely no conflicts of interest, there's a hundred sites that will tell you other things.
I check what these guys have to say, then you want to find out who the recommendations apply to. Do they apply to me because I'm different, I have a health condition or a family history? Am I in the right age category? Then you should do some research on the quality of the test. What's the likelihood of having a false positive?
One study followed 54,000 heavy smokers for seven years, they scanned them with CT scans and X-rays. What was the rate of lung cancer death in this medical trial? It was about 1.7 per cent. In terms of the benefit of screening to find that early, the benefit would be extremely small. The interesting thing is they found a lot of abnormalities in people's lungs. In fact 96 per cent of what they found wasn't cancer. It was things that were probably useless to diagnose. Things like moles, scars, cysts. Before getting a test you should know the probability of them finding something abnormal.
Tyee: That's a lot of research for your average patient, is it not?
Cassels: I think what I want my book to do is at least highlight the fact that you might have been told of the benefits and you might be worried about the condition, but that should kick start your research. That worry should not lead you straight to the test.
Tyee: Tell me what you learned on your own trip to the eye doctor that you write about in the book, where you were asked on the spot whether you wanted your eyeball pressure tested.
Cassels: Even someone whose very confident, like me, is intimidated by a health professional. It's hard to practice what you preach. I didn't realize it until I was there. If I'd known before hand that this was coming, I would have done the research. Reflecting on the eye test, it could have been much worse. They could have said you have high eyeball pressure, and suddenly I've gone from someone who never knew they were sick to someone who's now worried about possibly getting glaucoma and becoming blind.
Tyee: Wouldn't you want to avoid glaucoma?
Cassels: Exactly. But if the test has problems with it, like that 50 per cent of the people who develop glaucoma have normal eyeball pressure, or conversely a lot of people who have high eyeball pressure will never go on to develop glaucoma, without knowing this in advance you can make people really scared.
Tyee: But what if you're one of the 50 per cent who does have high eyeball pressure that turns out to be related to glaucoma?
Cassels: Just because you might be one of the lucky ones who would benefit doesn't mean you shouldn't do your research before you submit to it. I admit it's pretty hard when you're in the chair and even though you trust the health professional you know there are forces behind the decision to offer you a screening test. We know the major makers of eye drops that lower eyeball pressure sponsor glaucoma screening day. Why do they do that? Because they know the wider the net they throw the more potential patients they're going to have. The eye drops don't prevent glaucoma, they lower the pressure of your eyeball.
Tyee: Who benefits from over screening?
Cassels: Clearly it generates a lot of revenue for the people who do the screening, produce the drugs that treat the things they find, the radiologists that look at the mammograms for example. When you look at who are the big supporters behind some of the major screening initiatives, you see mostly people connected to the radiology community, and in the case of men's health, urology. If men refused PSA tests, the urology community would take a significant financial hit. Right now the business model depends on overdiagnosis and over treatment.
Tyee: My mother talks about being a physiotherapist in the 1960s and '70s when chest X-rays were done routinely on health professionals. At some point they stopped doing that, perhaps because of worries about the radiation.
Cassels: They did that to my father. They found something, did surgery and he died six months later. I don't know if it was related to the surgery, but my mother said he was never the same after the surgery. It was the same sort of thing, routine chest X-ray. In 1985 they just did it because that's what you do for an annual check-up. They don't do that anymore. Why? Because some critical research determined that you're going to find a lot of false positives and subject an awful lot of people to unnecessary surgery without saving any lives, so don't do it.
Tyee: Are you suggesting screening shortened his life?
Cassels: Don't know. Probably. The fact they don't do that kind of screening anymore suggests to me that cooler heads are prevailing and they've determined that the risks outweigh the benefits. I don't want to suggest I got interested in this topic because of my father.
Tyee: Who do you think should read your book?
Cassels: Ordinary citizens who are thinking about screening, questioning it. It's not really for health care professionals, but they'd benefit as well. If people are being offered something and they really don't know what questions to ask, I think that's the audience. I hope the people who are involved in the patient organizations read it. I would really be able to say to the people who volunteer their time to the osteoporosis society, the Alzheimer's society, the heart and stroke foundation, breast cancer advocacy people, I'd like those people to say "our organization needs to take a much more critical, appropriately critical, attitude toward screening, because right now we're acting like cheerleaders and we're probably doing the public a disservice because we're muddying the message."
Tyee: You're mostly known as a critic of the pharmaceutical industry. How much of a departure is this book, or are there parallels?
Cassels: The main similarity is this gap between the evidence and the marketing or the public on-the-street portrayal of treatment or screening. There's a huge gap in the pharmaceutical world between what the marketers or advertisers say and what the evidence says. In screening it's the same niche I'm going into. Here you can't point to one particular industry and say "these are the guys who are doing all this misleading stuff." It's a bigger tent. There's the patient advocates, the radiologists, the urologists, the specialists and the others who are pushing various types of screening. And the drug industry is there too. In almost every example I use of screening, there's a drug that treats the end result.
Tyee: Is it fair to say more research has been done on pharmaceuticals than on screening?
Cassels: Yes. You don't need to prove the benefits of a screening test before you launch it on the public. At least with a drug they have to have some proof it works before they launch it on the public. For the screening test you can just say, "we think glaucoma testing is good for the general public," and away we go. We don't have to test it, we don't have to prove it's effectiveness or safety or anything like that, we just do it.
Tyee: Do you have ADHD?
Cassels: Are you asking that because I turned back to my computer?
Tyee: No, because you said in your book that you screened positive for it based on an online test.
Cassels: Do I? I don't know but the seed's been planted. I wonder. Who doesn't? I'll just live with it. The whole self-screening thing is a fascinating topic. It's really about getting into the psychology of your own self-conception. "Do I have this? Maybe I have this? Sounds like I have this." I think people are very good at self-deception. You can convince yourself you've got almost anything.
Tyee: Now I'm sure there are people who will call the ideas in your book "dangerous" and will say you're going to prevent people from getting care and treatment for things that may be serious. How do you respond to that?
Cassels: I would say I'm not anti-screening. You should screen as much as you want. But if you want to make sure that you're prepared for what could go wrong, you should do your research first. You should do it with your eyes wide open. Some people might say I'm not going to get that PSA test or that mammography test. But as Cornelia Baines said to me once, a lot of women who refuse screening will live happily and long. Many women who go through screening will die because of breast cancer. Screening's not going to prevent it. We wish it did. But you've got to look at the hard facts.
Tyee: Do you think people's willingness to accept screening and to rely on it is in some ways related to our attitude as a culture to death and dying?
Cassels: By all means. We're conditioned to think we have to do everything we can to prevent illness before it strikes us and a lot of us are fearful of our mortality. And we're surrounded by people who claim to have been saved by various types of screening. Also, people don't want to regret not getting screened if it turns out later they have cancer. That's a powerful motivator.
Tyee: And in the book you suggest many doctors feel they have lawyers looking over their shoulders as they consider whether or not to recommend a screen.
Cassels: I'd have to say that's largely a U.S. phenomenon. There were stories told to me by various people I interviewed how a doctor had a male patient in his '60s, told him clearly about the advantages and disadvantages of a PSA test, the man refused it, six months later got prostate cancer and died. The family sued the doctor for negligence. The family ended up settling, but the doctors life was made hell. That sort of thing sends a ripple through the whole physician community that if you don't offer these tests and insist your patients get them, you can get sued. I think that's a largely US thing, but I think it motivates physicians here as well. It's crazy though. The main thing the doctor has to document, I think, is that they've had the discussion, told them the pros and cons. At the end of the day let's live with what the patient decides.
Tyee: As a 48-year-old male with a family history that includes cancer and a heart attack, are there any screenings you would get on a routine basis?
Cassels: At this age, no. I can't think of anything. The colorectal thing, I'll look at the evidence in five years and see what they say, but I'm really not worried about that. There's no family history of that. I eat a mostly vegetarian diet and not a lot of meat, nitrates and stuff like that which they think is linked to it. Even if I was a woman, like my wife, she doesn't need to get a pap smear every second year. It's good when you've got multiple partners and you're in your 20s or 30s, but when you've been married to the same person for 25 years, she'd be very low risk. It would probably be a waste of time.