Questioning Medicine: Breast Cancer Screening
Published: Oct 23, 2014 | Updated: Oct 30, 2014
Joe Weatherly, DO, and Andrew Buelt, DO, are family medicine residents in St. Petersburg, Fla. Together, they co-produce the podcast Questioning Medicine, where they deconstruct issues confronting today's clinicians. In this guest blog, Weatherly gives his take on breast cancer screening.
How Evidence Can Save More Breasts Than Screening
In 2014, there will be an estimated 1,665,540 cancer diagnoses, and approximately 585,720 deaths from cancer or complications from the treatment of cancer. Estimates are that 3% to 35% of cancer patients avoid premature death by screening alone.
This sounds wonderful. Those individuals and their stories are the poster children for preventive medicine. The cost and collateral impact on their lives is well worth it to those who prolong life and obtain "remission."
What we don't talk about are the potential harms false positives can have on the majority of those screened. The Susan G. Komen foundation website states ".... goal is to find cancer, not to avoid false- positive results." But false positives have consequences.
The screening machine spits out false positives, false negatives, and identifies positive cancer diagnoses that will not benefit from treatment.
We have sold America on the notion that breast cancer screening will reduce the risk of breast cancer death by more than 50%. And it will prevent death in more than 8% of the participants.
But according to Biller-Andorno et al., the screening process on its best day can provide a relative risk reduction of 20% and, in absolute terms, one breast cancer death per 1,000 women.
Catching Cancer
Whether detection through annual or biennial screening will add life to the patient is unclear. There is a lot of controversy in the literature over lead time bias, and how many cancers found in early stages may not manifest as clinically relevant or life-altering for many years, if at all.
Sadly, many of the more aggressive cancers that invade and kill younger women in the 40 to 50 age range grow so rapidly that they show negative at the time of mammography and metastatic by the next screen.
These few individuals must not be forgotten; however, it is unlikely that these individuals can be screened often enough to catch the cancer early. We need to rely on family history and employ high clinical suspicion of cancer during each clinical encounter with these individuals.
There are many syndromes associated with early onset of cancers, and other testing is available for these individuals to assess the likelihood of cancer.
False Positives
On the flip side, we have women with false negatives, and approximately as many false positives as we do true positives. The statement by foundations or groups to ignore the false positives and false negatives -- that they are simply part of the process -- reflects poorly on us all.
False positives need to be clearly discussed with the patient prior to the decision to be screened. I think of this similarly to having a mental health professional present or involved if there is a new HIV diagnosis given.
We have failed the individuals who are given a false-positive result. With the mindset of current guidelines, we are not concerned about the harms to a family when a cancer diagnosis is given to their mother, wife, or daughter when, more often than not, there is actually the expectation of no cancer diagnosis.
If we do not consider and discuss this, then we should not be allowed to order these tests. Similar to pain management, having the rights to certain medications and being the gatekeeper to multiple pain therapies, we need a "screening specialist" who can aid each individual in all of their screening discussions and help patients give true informed consent and manage the results of screening tests.
Biller-Andorno et al. wrote that 21% of screened detected cancers were overdiagnosed and resulted in needless surgery, radiotherapy, or chemotherapy. "In the best case, the small reduction in breast-cancer deaths was attenuated by deaths from other causes. In the worst case, the reduction was canceled out by deaths caused by co-existing conditions or by the harms of screening and associated overtreatment."
Benefits?
A Cochrane Review of seven trials, by Gøtzsche et al., involving women between the ages of 39 and 74, showed no evidence of an effect of mammography screening on overall mortality: "For every 2,000 women invited for screening throughout 10 years, one will avoid dying of breast cancer and 10 healthy women, who would not have been diagnosed if there had not been screening, will be treated unnecessarily." They also found that more than 200 women will be harmed from the distress of a false positive finding.
The screening test itself cannot be excluded as a harm. Mammography has the potential to cause up to one breast cancer per 1,000 women! Of all breast cancers detected by screening mammograms, up to 54% were estimated to be results of overdiagnosis, according to the National Cancer Institute.
In a review of Gøtzsche et al., David Newman, MD, shows in one graphic what is rarely told to women. To put it simply, NO women benefit from mammography. One in two are harmed, and one in five have harm in the form of an unnecessary surgical procedure over 10 years.
This is the type of CYA medicine that sacrifices the patient for the clinician.
I have much to learn about medicine, but discussing what medicine DOES know about a given intervention to the best of my ability so that informed decision-making can take place is where I am putting my time.
The "do it because I said so, and don't ask questions" attitude in medicine is part of the reason American healthcare is a mess. Physicians owe it to their patients to share our education, leave personal insecurities behind, and give them the power to make decisions and support them.
Teach your patient the risk at her age of being diagnosed with cancer over the next 10 years.
Mammography
Half of women have dense breast tissue. This makes mammograms virtually worthless. And five states have already passed laws which require radiologist to tell patients who have dense breast tissue this very thing. Your patient should hear this from you, not a radiologist.
I know many readers will say, they have a friend or relative who was diagnosed with breast cancer after screening, and that screening saved her life. As I stated above, I am so proud to be a part of medicine when it serves the needs of the individual.
I have a relative who was diagnosed in her 20s, and underwent bilateral mastectomies and a hysterectomy. I am grateful for the wise clinicians who aided her in her fight with cancer.
In writing this post, I was also made sadly aware of something that I didn't realize was part of the equation. A large 2013 retrospective analysis by Lu et al. found an increased risk for suicide and suicide attempts in adolescents and young adults after learning of a cancer diagnosis.
The relative risk of suicide completed or attempted in the first year after diagnosis of cancer is 1.6 to 2.0. When I prescribe annual mammography in low-risk 40-year-old women there is a 58% to 77% risk of false-positive result over 10 mammograms.
We should not take lightly the mantle of physician. Maintaining a keen awareness of how important our job is on a daily basis is what bridges the gap of uninterested clinician and avid reader and ultimate care provider.
Guidelines have evolved, with no baseline mammography recommended prior to 40. The science and technology of detection and therapies for cancer have all improved. But, I wonder, are we evolving with the process? Are we better at facilitating informed decisions and letting go of pasture medicine? I believe that we are.
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