Posts Tagged prostate cancer

Screening for disease in people without symptoms: The reality

One of the most contentious questions that come up in science-based medicine that we discuss on this blog is the issue of screening asymptomatic individuals for disease. The most common conditions screened for that we, at least, have discussed on this blog are cancers (e.g., mammography for breast cancer, prostate-specific antigen screening for prostate cancer, ultrasound screening for thyroid cancer), but screening goes beyond just cancer. In cancer, screening is a particularly-contentious issue. For example, by simply questioning whether mammography saves as many lives lost to breast cancer as advocates claim, one can find oneself coming under fire from some very powerful advocates of screening who view any questioning of mammography as an attempt to deny “life-saving” screening to women. That’s why I was very interested when I saw a blog post on The Gupta Guide that pointed me to a new systematic review by John Ioannidis and colleagues examining the value of screening as a general phenomenon, entitled “Does screening for disease save lives in asymptomatic adults? Systematic review of meta-analyses and randomized trials.”

Before I get into the study, let’s first review some of the key concepts behind screening asymptomatic individuals for disease. (If you’re familiar with these concepts, you can skip to the next section.) The act of screening for disease is based on a concept that makes intuitive sense to most people, including physicians, but might not be correct for many diseases. That concept is that early intervention is more likely to successfully prevent complications and death than later intervention. This concept is particularly strong in cancer, for obvious reasons. Compare, for example, a stage I breast cancer (less than 2 cm in diameter, no involvement of the lymph nodes under the arm, known as axillary lymph nodes) with a stage III cancer (e.g., a tumor measuring greater than 5 cm and/or having lots of axillary lymph nodes involved). Five year survival is much higher for treated stage I than for treated stage III, and, depending on the molecular characteristics, the stage I cancer might not even require chemotherapy and can be treated with breast conserving surgery (“lumpectomy” or partial mastectomy) far more frequently than the stage III cancer. So it seems intuitively true that it would be better to catch a breast cancer when it’s stage I rather than when it’s stage III.

Posted in: Cancer, Clinical Trials, Epidemiology, Public Health

Leave a Comment (65) →

Another Misguided Cancer Testimonial

An economic analyst, Mike “Mish” Shedlock, wrote a blog post to describe how he beat prostate cancer. When laymen and patients write about cancer, they are likely to get some things wrong. Mish’s story is full of typical misunderstandings and misinterpretations.

He interpreted his experience in his own way and did his own research into the medical literature, something he was not qualified to do. Prostate cancer is a very complex subject, and understanding the implications of published studies for treating patients can be difficult even for experts. In typical Dunning-Kruger fashion, he rejected the advice of his doctors, thinking he could do better.

Posted in: Cancer, Herbs & Supplements

Leave a Comment (129) →

A Skeptical Look at Screening Tests

I’m going to follow Mark Crislip’s example and recycle my presentation from The Amazing Meeting last week, not because I’m lazy or short on time (although I am both), but because I think the information is worth sharing with a larger audience.

We’ve all had screening tests and we’re all likely to have more of them, but there is a lot of misinformation and misunderstanding about what screening tests can and can’t do. Screening tests are done on populations of asymptomatic people and must be distinguished from diagnostic tests done on individual patients who have symptoms. Some tests are excellent for diagnostic purposes but are not appropriate for screening purposes.

We’re constantly being admonished to get tested for one thing or another. A typical example was a recent Dear Abby column. She got a letter from a woman who had been screened for kidney disease and learned that she had a mild decrease in kidney function. Abby was shocked to learn that 26 million Americans have chronic kidney disease, and she advised her readers to get their kidneys checked. This was terrible advice. It superficially seems like good advice, because if you have something wrong with your kidneys, you’d want to know about it, right? In fact, if there was anything wrong anywhere in your body, you’d want to know about it. By that logic, it might seem advisable to test everyone for everything. But that would be stupid. It would find lots of false positives, it would create anxiety by picking up harmless variants and anomalies that never would have caused problems, it would be expensive, and it would do more harm than good.

Posted in: Cancer, Diagnostic tests & procedures

Leave a Comment (24) →

Once more into the screening breach: The New York Times did not kill your patient

One of the more depressing things about getting much more interested in the debate over how we should screen for common cancers, particularly breast and prostate cancer, is my increasing realization of just how little physicians themselves understand about the complexities involved in weighing the value of such tests. It’s become increasingly apparent to me that most physicians believe that early detection is always good and that it always saves lives, having little or no conception of lead time or length bias. Sadly, just last week, I saw another example of just this phenomenon in the form of an article written by Dr. George Lombardi entitled My Patient, Killed By The New York Times. The depth of Dr. Lombardi’s misunderstanding of screening tests permeates the entire article, which begins with his recounting a story about a patient of his, whose death he blames on The New York Times. After describing the funeral of this 73-year-old man who died of prostate cancer, Dr. Lombardi then makes an accusation:

This one filled me with a special discomfort as I knew a secret: He didn’t have to die. I knew it and he had known it. Had he told?

About 5 years ago he had just retired and had a lot more time on his hands. He was a careful man, lived alone, considered himself well informed. He got into the habit of clipping articles on medical issues and either mailing them to me or bringing them in. They came from a variety of sources and were on a variety of topics. He wasn’t trying to show me up. He was genuinely curious. I kidded him that maybe he’d like to go to medical school in his retirement. ‘No’ he laughed, ‘I just like to be in the know.’

When he came in for his physical in 2008 he told me he’d agree to the DRE but not the PSA (his medical sophistication extended to the use of acronyms: DRE stands for digital rectal exam where I feel the prostate with my gloved finger for any abnormality and PSA for prostatic [sic] specific antigen which is a blood protein unique to the prostate and often elevated in prostate cancer). He had read that the use of PSA as a screening test was controversial. This was the year that the United States Preventive Services Task Force, a government panel that issues screening guidelines, recommended against routine PSA screens for older men. It was often a false positive (the PSA was elevated but there was no cancer), led to unnecessary biopsies, and besides most prostate cancers at his age were indolent and didn’t need to be treated. I countered that prostate cancer was the second leading cause of cancer deaths in men and that it was better to know than not to know. This way it would be our decision. The patient with his doctor deciding what was best. But no, he wanted to stick to his guns and since the DRE was normal no PSA blood test was sent.

After describing a conversation with the man’s daughter, who said, “My father was killed by The New York Times,” Dr. Lombardi then goes on to anecdotal evidence and a cherry-picked publication to support his view, quoting an oncologist who says he’s “seeing more men presenting with advanced prostate cancer” and then referring to a single paper in the current Annals of Internal Medicine about PSA screening. Before I look at the article and a recently published paper on screening mammography that made the news, I can’t help but point out that I (mostly) agree with Dr. Lombardi when he says:

Public health doctors, policy experts and journalists tend to look at the population as a whole. It is a better story if it is one story. It makes a better headline. Their statistics are people I sit across from everyday trying to figure out what the future holds. We each have our job to do.

The problem is, of course, that Dr. Lombardi takes that observation and draws the wrong conclusion, namely that his patient died because of lack of screening. He attacks a straw man, sidestepping the true argument, namely that evidence shows that PSA screening probably causes more harm than good for men at average risk of prostate cancer. Unfortunately, Dr. Lombardi obviously does not understand some very basic concepts behind cancer screening, nor does he apparently recognize that doctors who deal with the population-level data that we have regarding screening tests and try to apply them to individual patients are actually looking in a very systematic way about what the benefits of screening are to the individual patient. More on that later. In the meantime, although I wouldn’t go quite as far as Dr. John Schumann did in criticizing Dr. Lombardi, I do view his lament as a jumping off point to look at some recent data on screening for the two most common cancers, breast and prostate.


Posted in: Cancer, Diagnostic tests & procedures, Politics and Regulation, Public Health, Science and the Media

Leave a Comment (39) →

Prostate Cancer Dilemmas: To Test or Not to Test, To Cut or Not to Cut

The issue of PSA screening has been in the news lately. For instance, an article in USA Today reported the latest recommendations of the US Preventive Services Task Force (USPSTF): doctors should no longer offer the PSA screening test to healthy men, because the associated risks are greater than the benefits. The story was accurate and explained the reasons for that recommendation. The comments on the article were almost uniformly negative. Readers rejected the scientific evidence and recounted stories of how PSA screening saved their lives.

It’s not surprising that the public fails to understand the issue. It’s complicated and it’s counterintuitive. We know screening detects cancers in an early stage when they are more amenable to treatment. Common sense tells us if there is a cancer present, it’s good to know about it and treat it. Unfortunately, common sense is wrong.  Large numbers of men are being harmed by over-diagnosis and unnecessary treatment, and surgery may not offer any advantage over watchful waiting. (more…)

Posted in: Cancer

Leave a Comment (34) →

Cancer prevention: The forgotten stepchild of cancer research?

The New York Times has been periodically running a series about the “40 years’ war” on cancer, with most articles by Gina Kolata. I’ve touched on this series before, liking some parts of it, while others not so much. In particular, I criticized an article one article that I thought to be so misguided about how the NIH grant system leads researchers to “play it safe” and how we could cure cancer if we could just fund “riskier” research that I had to write an extended screed about the misconceptions in the article. The latest installment, Medicines to Deter Some Cancers Are Not Taken, also by Kolata, is much better in that it discusses a problem at the heart of cancer, namely that we have developed drugs that can decrease the risk of specific cancers but they are not as widely used as they could be.

The first part of the article contrasts a seeming incongruity:

Many Americans do not think twice about taking medicines to prevent heart disease and stroke. But cancer is different. Much of what Americans do in the name of warding off cancer has not been shown to matter, and some things are actually harmful. Yet the few medicines proved to deter cancer are widely ignored.

Take prostate cancer, the second-most commonly diagnosed cancer in the United States, surpassed only by easily treated skin cancers. More than 192,000 cases of it will be diagnosed this year, and more than 27,000 men will die from it.

And, it turns out, there is a way to prevent many cases of prostate cancer. A large and rigorous study found that a generic drug, finasteride, costing about $2 a day, could prevent as many as 50,000 cases each year. Another study found that finasteride’s close cousin, dutasteride, about $3.50 a day, has the same effect.

This is indeed a contrast. Think about it. Millions of Americans take statins, for instance, to lower their cholesterol and thereby try to prevent the complications of elevated cholesterol, such as heart disease, vascular disease, and strokes. Yet, for at least two common cancers, there are proven effective drugs that will lower the risk of cancer considerably with a side effect profile at least as favorable as that of statins.

Posted in: Cancer, Clinical Trials, Herbs & Supplements, Nutrition, Politics and Regulation

Leave a Comment (8) →

The cancer screening kerfuffle erupts again: “Rethinking” screening for breast and prostate cancer

I see that the kerfuffle over screening for cancer has erupted again to the point where it’s found its way out of the rarified air of specialty journals to general medical journals and hence into the mainstream press.

Over the last couple of weeks, articles have appeared in newspapers such as the New York Times and Chicago Tribune, radio networks like NPR, and magazines such as TIME Magazine pointing out that a “rethinking” of routine screening for breast and prostate cancer is under way. The articles bear titles such as A Rethink On Prostate and Breast Cancer Screening, Cancer Society, in Shift, Has Concerns on Screenings, Cancers Can Vanish Without Treatment, but How?, Seniors face conflicting advice on cancer tests: Benefit-risk questions lead some to call for age cutoffs, and Rethinking the benefits of breast and prostate cancer screening. These articles were inspired by an editorial published in JAMA last month by Laura Esserman, Yiwey Shieh, and Ian Thompson entitled, appropriately enough, Rethinking Screening for Breast Cancer and Prostate Cancer. The article was a review and analysis of recent studies about the benefits of screening for breast and prostate cancer in asymptomatic populations and concluded that the benefits of large scale screening programs for breast cancer and prostate cancer tend to be oversold and that they come at a higher price than is usually acknowledged.

For regular readers of SBM, none of this should come as a major surprise, as I have been writing about just such issues for quite some time. Indeed, nearly a year and a half ago, I first wrote The early detection of cancer and improved survival: More complicated than most people think. and then followed it up with Early detection of cancer, part 2: Breast cancer and MRI. In these posts, I pointed out concepts such as lead time bias, length bias, and stage migration (a.k.a. the Will Rogers effect) that confound estimates of benefit due to screening. (Indeed, before you continue reading, I strongly suggest that you go back and read at least the first of the aforementioned two posts to review the concepts of lead time bias and length bias.) Several months later, I wrote an analysis of a fascinating study, entitling my post Do over one in five breast cancers detected by mammography alone really spontaneously regress? At the time, I was somewhat skeptical that the number of breast cancers detected by mammography that spontaneously regress was as high as 20%, but of late I’m becoming less skeptical that the number may be somewhere in that range. Even so, at the time I did not doubt that there likely is a proportion of breast cancers that do spontaneously regress and that that number is likely larger than I would have guessed before the study. Of course, the problem is that we do not currently have any way of figuring out which tumors detected by mammography will fall into the minority that do ultimately regress; so we are morally obligated to treat them all. My most recent foray into this topic was in July, when I analyzed another study that concluded that one in three breast cancers detected by screening are overdiagnosed and overtreated. That last post caused me the most angst, because women commented and wrote me asking me what to do, and I had to answer what I always answer: Follow the standard of care, which is yearly mammography over age 40. This data and these concerns have not yet altered that standard of care, and I am not going to change my practice or my general recommendations to women until a new consensus develops.

Posted in: Cancer, Diagnostic tests & procedures, Public Health, Science and the Media

Leave a Comment (10) →

PSA – To Screen or Not to Screen

You’ve all heard the dramatic testimonials in the media: “I had a PSA test and they found my prostate cancer early enough to treat it. The test saved my life. You should get tested too.” The subject of screening tests is one that confuses the public. On the surface, it would seem that if you can screen everyone and find abnormalities before they become symptomatic, only good would result. That’s not true. Screening tests do harm as well as good, and we need to carefully consider the trade-offs.

About half of American men over the age of 50 have had a PSA (prostate-specific antigen) screening test for prostate cancer. Recommendations for screening vary. The US Preventive Services Taskforce (USPSTF) says there is insufficient evidence to recommend screening. The American Urological Association and the American Cancer Society recommend screening. Urologists practice what they preach: 95% of male urologists over the age of 50 have been screened. But other groups like the American Academy of Family Physicians recommend discussing the pros and cons of screening with patients and letting them make an informed choice.

Two recent studies published simultaneously in The New England Journal of Medicine have added to the controversy. One concluded that screening does not reduce deaths from prostate cancer; the other concluded that it reduces deaths by 20%. (more…)

Posted in: Clinical Trials, Diagnostic tests & procedures

Leave a Comment (19) →