And for those who may have forgotten, yes you should do them even if you are pregnant or breastfeeding. ☺
The Reader's Digest had a very interesting article in the current issue (April 09) about cancer screenings, so I thought I'd share from that this month. (It's particularly interesting in light of the mixed reviews I found when I wrote about mammograms a few months ago.) Please note that the screenings this article is talking about are the ones done in the doctor's office--the kind that find things you would not notice on your own. Obviously, if you have symptoms (such as a lump in your breast) you should get it checked out. Of course you should still do self-exams. All this is questioning is the wisdom of doing screenings (such as mammograms and colonoscopies) if you have no other symptoms...
So here I quote from them at length.
It's hard to believe, but some researchers [say] that yearly mammograms are not nearly as effective at reducing the risk of dying of breast cancer as most women think, and that mammography leads many women to get unnecessary treatment -- especially those diagnosed with DCIS [ductal carcinoma in situ]. The problem is bigger than just mammography: They say the prostate-specific antigen (PSA) test may do men more harm than good if they don't already have symptoms of prostate cancer. And they have similarly grim things to say about other widely used cancer screening tests.
Their view stands in stark contrast to the message being put out by groups like the American Cancer Society and even the federal government, which say that finding and treating tumors as early as possible is the surest way to avoid a cancer death. But a growing group of scientific heretics -- published in highly respected medical journals, working at some of the most august institutions -- strongly believe that it's time to rethink our whole approach to cancer screening.
That's because screening tests pick up many small cancers that would never have caused any symptoms. "Screening for cancer means that tens of thousands of patients who never would have become sick are diagnosed with this disease," says H. Gilbert Welch, MD, codirector of the Outcomes Group at the Veterans Affairs Medical Center in White River Junction, Vermont, and a leading expert in cancer screening. "Once they're diagnosed, almost everybody gets treated -- and we know that treatment can cause harm." Tamoxifen for breast cancer can trigger life-threatening clots in the lungs, for instance. Surgery for prostate cancer leaves 60 percent of men unable to have an erection. For that matter, some of the screening tests themselves carry risks: Up to 5 out of every 1,000 people who get a colonoscopy have a serious complication, such as a colon perforation or major bleeding.
Most people diagnosed with cancer undoubtedly see these risks as the price they must pay to avoid dying of cancer. "The reality is not so simple," says Dr. Welch. Screening tests are very good at catching tumors that would never bother us, he notes, but they're actually pretty bad at catching the fastest-growing and most deadly cancers in time to cure them. The bottom line, says researcher Floyd Fowler, Jr., PhD, president of the Boston-based nonprofit Foundation for Informed Medical Decision Making: "Screening's power to cut your risk of dying has been wildly overinflated."How Cancer Can Fool a Screening Test
The idea that getting tested for cancer might be useless or even harmful may strike you as completely wrongheaded. After all, smaller cancers are easier to cut out. They're also less likely to have metastasized, or spread to other parts of the body -- and metastasis is generally what makes cancer deadly. Sure, it's possible for a tumor to kill without metastasizing: A brain tumor, for example, can cause devastating harm when it grows big enough to squeeze healthy tissue inside the skull. But most cancers threaten life only after a few cells break free and travel through the bloodstream or lymph fluid to set up shop in another part of the body. Once that's happened, a surgeon can no longer cure a patient by removing the tumor. And even powerful chemotherapy drugs are often unable to kill every last errant cell.
Physicians used to think that a tumor needed to get to a certain size before it would spread. But that's not necessarily so, says Barnett S. Kramer, MD, associate director for disease prevention at the National Institutes of Health. "Some tumors spread extremely early," he says. They begin metastasizing when they consist of only a few million cells, which sounds like a lot but is smaller than the period at the end of this sentence -- too small to detect with most screening tests. By the time this kind of cancer is big enough to be seen on a mammogram or other test, it's already sent seeds to other parts of the body.
The flip side of this problem is that many screening tests do a great job at catching cancers that would never have caused problems and could simply have been left alone. This notion violates most of what we think we know about cancer, says Dr. Kramer, because most of what we know is based on the tumors that cause harm. If you think of all the different varieties of cancer as making up an iceberg, cancers that cause symptoms represent only the part of the berg above the waterline. For most of human history, these were the only tumors we knew anything about: the breast cancer that had grown big enough to feel, the lung cancer that was causing shortness of breath.Screening allows us to look under the water, at the tumors that haven't yet become symptomatic. We assume they will eventually cause symptoms, but increasing evidence suggests that's not always the case. Evidence from autopsies, for instance: In one study, postmortem exams showed that nearly 9 percent of women of all ages who died of any cause other than breast cancer had undiagnosed DCIS. Among women from Denmark, where mammography is not as common as it is here, a whopping 39 percent of middle-aged women who died of other causes had undetected breast cancers. Similarly, says outcomes researcher Dr. Welch, a 1989 study found that 60 percent of men over age 60 have undetected prostate cancer -- yet only about 3 percent of deaths in men are due to prostate cancer.
The Damage Screening Can Do
Forget the fact that unnecessary therapies for cancer are a tremendous drain on our health care budget, already strained to the breaking point. "Many oncologists would probably tell you that they've had patients who suffered serious side effects, even death, from treatment that they might not have needed," says William C. Black, MD, a professor of radiology at Dartmouth-Hitchcock Medical Center. No one intentionally prescribes unnecessary treatment, of course. But it's often difficult to know if a patient really needs to be treated, so the tendency is to be aggressive, just in case.
Does Screening Save Lives?
For many people, even serious side effects [would] be worth putting up with if the treatment reduced their risk of dying of cancer. That's the point of getting screened, isn't it? Yet only one cancer screening test, the venerable Pap smear, has truly slashed the risk of death. Between 1955 and 1992, according to the American Cancer Society, Pap smears cut the death rate for cervical cancer by 74 percent, and deaths have continued to decline each year.
Mammograms also offer a smaller benefit than many patients -- and doctors -- assume. Mammography's effectiveness has been hotly debated, but a carefully conducted 2005 analysis suggests it cuts the risk of dying of breast cancer by 15 percent, says the NIH's Kramer. That means a 60-year-old who gets regular mammograms shaves her risk of dying of the disease in the next decade from 7 per 1,000 to 6 per 1,000.
[This section also contained specifics about the effectiveness--or lack thereof--of colonoscopies and prostate cancer screenings...]To Screen or Not to Screen
The fact is, there's no single answer. It depends on many factors, including how old you are, what other diseases you have, and what you value most in terms of your health...
Eventually, researchers and doctors hope, better screening tests will be able to distinguish between cancers that need to be treated and those that don't. But until then, many experts believe, the decision to get screened should rest on an individual's values and his or her ability to handle uncertainty. "We have come to fear dying from disease more than dying at the hands of overzealous doctors," says Dartmouth's Dr. Black. The fact is, both are risks when we get screened for cancer.
Check out these books, which help with decisions about testing and treatment:
- Should I Be Tested for Cancer? by H. Gilbert Welch, MD
- Know Your Chances: Understanding Health Statistics by Steven Woloshin, MD, Lisa M. Schwartz, MD, and H. Gilbert Welch, MD
Screening might be right for you if:
- You have a family history. If you have close relatives with cancer, your own risk of developing it may be above average. Generally only immediate relatives (mother, father, sibling, child) count toward your family history.
- You know you have a risky mutation. The BCRA1 and 2 mutations are known to increase the risk of breast and ovarian cancers. Other mutations have been tied to colon cancer.
- You've already had cancer. One bout slightly increases your odds of developing another, unrelated cancer.
- You have another serious illness. Having heart disease or suffereing a stroke increases the odds that you'll die before an undetected cancer could cause symptoms.
- You're under 50 or over 70. there's less evidence to support getting screened in your 40s, when cancer risk is low. After 70, the possible benefit from early treatment should be weighed against the chance that it will make life less enjoyable or more painful.
- You're frail. If you can't withstand treatment, it may not be useful to undergo a screening test.
- You're particularly afraid of being harmed by treatment you don't need.