THE INSTANT my wife gets a reminder letter that her mammography is due she crams it back into the envelope and tries to forget about it. But only for a day or two. Like millions of women throughout the Western world she dutifully makes an appointment. Why? Because screening for breast cancer saves lives. Doctors keep telling her so. With its promise of early detection, screening has to make sense. Doesn鈥檛 it?
Well, not necessarily, if you listen to a pair of Danish researchers. They ignited a fierce dispute a couple of years ago when they said that mammography screening could be harmful. Nor is this the only dispute in cancer screening. Some doctors advocate testing programmes for prostate and testicular cancer, while others say this would be a disaster. Patient groups have joined in, and the arguments have got so heated that some of those involved have resorted to posting personal abuse on the Internet and lobbying for their opponents to be sacked.
In many countries breast screening has an almost sacrosanct status. Women over a certain age, varying from about 40 to 50 depending on the country, are supposed to go every few years for a breast X-ray known as a mammogram. Any suspicious signs are followed up with further tests. Roughly 1 in 160 British women who go for a mammogram end up being treated for breast cancer.
Advertisement
But for years, critics have been claiming that we don鈥檛 know for sure that such programmes produce any overall benefit. They point out that breast screening itself is not without its risks, such as false alarms that can put women through months of agonising worry. Even worse, because neither mammograms nor the follow-up tests are 100 per cent accurate, some women inevitably end up being treated for cancer when they don鈥檛 actually have it. Screening can detect changes in breast cells that make them look cancerous when they are not. It can also identify small tumours that are growing so slowly the woman will die of some other cause. As a result, some women undergo unnecessary surgery, chemotherapy and radiotherapy, with their attendant risks of post-operative complications, serious infections and other side effects.
The debate has rumbled on for years, with some trials suggesting a benefit from screening and others more equivocal. The latest, very public, phase of the row erupted after a statistical analysis of all seven previous studies worldwide by two researchers at the Nordic Cochrane Centre in Copenhagen, part of an international network dedicated to compiling objective reviews of medical treatments. They concluded that five of the trials were flawed, particularly in the methods used to ensure that the women in the unscreened groups were truly comparable with those who had undergone screening. Worryingly, the two remaining trials found screening had no effect on overall death rates. What screening did do was cause women to receive more medical interventions to treat cancer: surgical removal of the lump or the breast, and radiotherapy. As there was no change in overall death rates, the researchers concluded that any fall in cancer deaths was being cancelled out by deaths from the unnecessary treatments. That鈥檚 right: some women were being killed by the screening programme.
As is customary, the researchers submitted their analysis to the Cochrane editorial panel. But the committee insisted on cutting the more controversial parts, re-angling the report to be more positive about screening. Unhappy with what he views as censorship, co-author Peter Gotzsche sent his unedited report to The Lancet, which published it last year (vol 358, p 1340). So now there are two versions with different conclusions.
Screening organisations rejected Gotzsche鈥檚 claims and attacked the researchers for scaring women away from mammograms. In Britain, Julietta Patnick, national coordinator for the NHS breast screening programme, says: 鈥淢any British screening experts questioned the value of this review. We know that breast screening works and encourage women to accept their invitation for screening.鈥� Gotzsche鈥檚 mailbox has been bombarded by complaints from supporters of screening. 鈥淥ften the arguments have not been very scientific,鈥� he observes. 鈥淭here is so much belief involved in this, it sometimes seems almost religious to me.鈥�
The Danish researchers remain a minority voice鈥攎ost doctors still support mammography screening. In America, where you get whatever healthcare you choose to pay for, it鈥檚 pretty much taken for granted that women over 50 should have mammograms: the only debate is whether 40-to-50-year-olds should have them too. And worldwide, the pro-screening lobby has been fighting back. Since Gotzsche鈥檚 report, two more analyses have been published鈥攐ne also in The Lancet, and one by a division of the World Health Organization鈥攚hich both came down in favour of screening. But the matter is unlikely to end there. Gotzsche is already preparing a response to the latest criticisms of his work, and says he has no intention of abandoning the fight.
These sorts of debates are happening about other screening programmes too. It鈥檚 increasingly being realised that just because a new medical test has been invented that can show up a higher-than-average probability of cancer or any other disease, it doesn鈥檛 mean that everyone should routinely get the test. Set against the obvious pluses, there might be disadvantages: the test might not be very reliable, or it might be so expensive that the money would be better spent on more effective treatments.
In fact, pro-screening doctors have already ended up with egg on their faces from being too gung-ho about a separate programme: breast self-examination. Time was when women couldn鈥檛 open a magazine or visit their GP without being urged to painstakingly check their breasts once a month for suspicious lumps and bumps. The logic seemed irrefutable. Women might discover a cancer, and after all, what could be the harm?
But when researchers finally got around to doing rigorous studies, they found that self-examination didn鈥檛 cut the number of women dying from breast cancer. That鈥檚 because women already tend to notice genuine cancers without special checks, when they鈥檙e bathing or dressing, for example. Ritual self-examination also caused unnecessary anguish. The vast majority of breast lumps are not cancerous and don鈥檛 need any treatment. Women who dutifully did their checks sometimes ended up rushing to their GP thinking they were under a death sentence when there was nothing really wrong.
So out went breast self-examination, and in came the curiously named policy of 鈥渂reast awareness鈥�. The thinking in most countries is that women shouldn鈥檛 bother with ritual monthly checks, but should still have an idea what their breasts feel like normally, so they notice any new lumps.
Joan Austoker, director of the Primary Care Education Group at the charity Cancer Research UK, and one of the pioneers of the new approach, explains: 鈥淚t was important that women didn鈥檛 stop being aware of their breasts because the majority of problems are found by women themselves. It鈥檚 getting away from the ritualistic approach where you have to do something in a set way.鈥�
Most doctors now agree that any screening programme must meet numerous criteria before it is introduced. The UK National Screening Committee (NSC), which advises the government, lists 19 of them. These include the existence of an effective treatment for patients who test positive, and the rather obvious requirement that the programme鈥檚 benefits should outweigh any physical and psychological harm. Arguably the most important is that the screening programme has been tested out first in a large randomised controlled trial, in which the overall health of people who take the test is compared with that of people who don鈥檛.
But that hasn鈥檛 deterred some pressure groups from lobbying for more screening programmes, even in the absence of good evidence. Take prostate cancer, for example. This disease, which mostly affects men over 65, is sometimes linked with raised blood levels of a substance called prostate-specific antigen or PSA. Normal prostates make small amounts of it; cancerous prostates tend to produce more. But there is no firm dividing line, and two-thirds of men with a raised PSA level show no signs of a tumour.
There are other downsides. The commonest treatments for prostate cancer can have rotten side effects, notably impotence and incontinence. And yet for many men who undergo prostate surgery, medical intervention might never have been necessary. Cancers of this organ are usually extremely slow-growing, and a typical man with prostate cancer is more likely to die from other causes before his tumour kills him. Doctors have a saying that most men die with prostate cancer, but not of it.
In Britain, the NSC has rejected this form of screening, saying there is not yet enough evidence for a benefit. But in the US, where patient pressure is a more powerful driving force, PSA testing is becoming commonplace: middle-class dinner parties can be the setting for men of a certain age swapping PSA scores. But not all US doctors like this trend. Gavin Yamey, deputy editor of the California-based Western Journal of Medicine, recently co-wrote an editorial in that publication and an article in the San Francisco Chronicle disparaging routine PSA testing.
Yamey told 快猫短视频: 鈥淵ou have taken a man who would never have known about his cancer, and you鈥檝e given incontinence, impotence and fear. The risks of doing this are greater than the likelihood of saving a life.鈥�
Yamey鈥檚 articles prompted calls for the authors to be fired from the WJM and, in the case of his co-author Michael Wilkes, from his teaching work at the University of California at Davis. 鈥淪ome of this backlash was from powerful patient support groups,鈥� says Yamey. 鈥淎 message went out to people belonging to one prostate cancer email group urging them to write to our office asking for us to be silenced. We got a lot of hate mail calling us, among other things, murderers.鈥� He says they were even compared to the Nazi doctor and war criminal Josef Mengele. Yamey also claims that some of the protests are underpinned by commercial interests. 鈥淚鈥檓 aware of groups that have received funding from companies with a financial stake in offering tests or treatment,鈥� he says.
A male parallel to the breast self-examination fiasco may also be in the making. Some doctors are encouraging testicle self-examination, with many cancer and men鈥檚 health groups urging monthly inspections with evangelical zeal. But the weight of evidence is against regular ritual checks. Most testicle cancers make their presence felt with symptoms like an ache, swelling or heaviness, and the main problem is not discovering the tumour, but getting men to go to their GP straight away. Glasgow urologist David Kirk says: 鈥淲e see chaps who鈥檝e known for months that they have a lump in their scrotum and done nothing about it.鈥�
Hysteria
And getting men to feel themselves for lumps produces too many 鈥渇alse positives鈥� for what is an extremely rare disease. Western men have an average 0.005 per cent lifetime risk鈥攃ompare this with women鈥檚 11 per cent breast cancer risk. The dispute has even spilt over into the British tabloid press. Keith Hopcroft, an Essex GP with an interest in men鈥檚 health, recently wrote an article in The Sun arguing that ritual self-examination was 鈥渄aft nonsense鈥�. He was accused by Nottingham-based self-help organisation the Testicular Cancer Group of setting back men鈥檚 health by years and wanting to 鈥渇orget鈥� about testicular cancer. 鈥淭he reaction becomes quite hysterical,鈥� says Hopcroft. 鈥淭here鈥檚 a reflex indignation, partly because they feel you鈥檙e questioning their very existence.鈥�
If and when the arguments over breast, prostate and testicular cancer are resolved, they won鈥檛 be the last. The NSC is currently considering a programme to detect bowel cancer. Most tumours bleed, even if only in microscopic amounts. People can be asked to provide a smear of faeces and, if blood traces are found, be offered further tests. But the committee is taking a cautious approach. Perhaps mindful of the brouhaha over breast screening, they want to be absolutely certain of the evidence. They have set up two pilot screening programmes, one in and around Coventry, the other in Scotland. After the trials finish next year, the committee will recommend whether or not the scheme should go national. If only the enthusiasts for mammography screening had been so cautious back in the seventies and eighties.
No one is saying that people should relinquish responsibility for their own health. If anyone notices a lump in their breast or testicle then obviously they should see their doctor. But encouraging people to do this is a world away from spending time and resources on urging happy, healthy people to check themselves regularly or to have medical tests. And money squandered on campaigns for pointless self-examination would be better spent on chemotherapy or cancer prevention efforts.
Whether we actually follow these priorities is another matter, however. These days, health professionals don鈥檛 always get to call the shots. 鈥淧eople are challenging the culture we use to make decisions,鈥� says Muir Gray of the NSC. 鈥淭hey are saying: 鈥業f I want to know my PSA, I鈥檓 entitled to know it.'鈥�
Even in Britain鈥檚 cash-strapped National Health Service, men can still get a PSA test, as long as they have been warned about the test鈥檚 inadequacies and the treatment problems. 鈥淭hat鈥檚 part of consumerism in healthcare,鈥� says Gray. 鈥淚f the testing process is a means of controlling anxiety about prostate cancer鈥攖hat is, if they get a low reading they believe they don鈥檛 have it鈥攖hen it becomes an anxiety-management programme.鈥�
His view is echoed by Roger Kirby, professor of urology at St George鈥檚 Hospital Medical School in London. Ideally, he says, you would wait until the evidence accumulates. But 鈥渢he reality is that people are not prepared to wait because they鈥檙e worried that they鈥檙e going to die before the evidence emerges. Public sentiment sometimes drives medicine more than evidence鈥�, he says.
Doctors and politicians face some hard choices. Questioning screening programmes that people have put their faith in is bound cause upset, and risks calling into question doctors鈥� credibility. But ploughing on with discredited tests can鈥檛 be the answer, either. However well intentioned it is, a screening system founded on half-baked science is bound, sooner or later, to fall apart.