II. Does early detection save lives?
“…tell everyone they have cancer, and survival rates will skyrocket” — Gilbert Welch
According to the American Cancer Society, there will be an estimated 1,735,350 new cancer cases and 609,640 cancer deaths. It is common knowledge that “early detection saves lives” and that cancer screening has served to prevent deaths. Non-profits, such as the Susan Komen Foundation, have championed this cause fervently, and as a result, mammography to detect breast cancer has become the cornerstone of this movement.
However, recent debate regarding the benefits of cancer screening have called into question its efficacy in preventing cancer deaths. In fact, it appears that cancer cases have been inflated through overdiagnosis, especially in the “scrutiny-dependent” cancers such as the cancers of breast, prostate and thyroid. For example, men with a family history of prostate cancer are more likely to get Prostate Specific Antigen (PSA) testing than men without such history, even though it has been shown that risk due to family history has been overestimated by nearly half. Another study showed that cases of thyroid cancers were reaching epidemic proportions due to false diagnosis; an estimated one-half of breast cancers detected by screening would have remained harmless even if they weren’t treated. A long-term followup study showed that 1/4th of cases in a randomized clinical trial were overdiagnosed.
While the screening tests themselves are not expensive (PSA test — $60–80, thyroid screening — $30) and some, like mammograms, are completely covered by insurance, the consequences of overscreening are much more dire. In a retrospective study, it was found that more than a million women diagnosed and treated for early stage breast cancer were treated for “cancers” that wouldn’t have progressed or caused harm. Another study with over 600,000 women showed no clear evidence that mammograms resulted in a reduction in overall mortality. Early diagnosis does increase survival rates — it is only logical that people who get diagnosed earlier in life will have a longer time of survival even if their time of death doesn’t change. Additionally, overdiagnosis of harmless or indolent cancer (cancers that do not progress), only serves to inflate survival rates and add more patients on the ever-growing list for receiving expensive treatment. The economic costs are also significant — false positives in PSA testing contributes to more than a million prostate biopsies ($1,500), in addition to other externalities such as hospital admission and mental health issues. False positives in breast cancer screening have been associated with psychosocial distress even after 6 months post-screening.
The mantra “early detection saves lives” has successfully brainwashed the public into believing that it actually prevents cancer deaths effectively — in one study, 68% women thought that mammography lowers their risk of getting breast cancer, 62% were convinced that screening decreased the rate of breast cancer by half, and 75% thought 10 years of screening would prevent 10 breast cancer deaths per 1000 women. Unfortunately, this mantra has allowed non-profits such as Susan Komen Foundation to balloon with less and less of the raised money going to supporting actual research and more into maintaining the foundation itself.
With the advent of genetic testing, profiting off of overdiagnosis has taken cover under technological progress. A great example of this is the case of Myriad Genetics, that profited off of a patent on BRCA genes (inherent mutations in these genes result in familial breast and ovarian cancers) from 1996 to 2013 when the patent was declared invalid. However, by that time, Myriad had already raked in $2 billion with tests priced at $4,000. When competitors started offering cheaper tests, Myriad employed aggressive marketing tactics to slander their tests by describing them to be “inaccurate” and boasting the superiority of its own tests based on a proprietary database of 17,000 variants in the BRCA genes it built over 20 years thanks to the patent (experts noted that Myriad’s inaccuracy claims were false). Ironically, the inaccuracies described by Myriad could have been improved upon by independent scientists had it not patented the genes.
The obsession with early detection has resulted in a gold rush to develop “liquid biopsies”, a technique where a patient’s blood sample will be screened for known cancer biomarkers. However, the case of Theranos should serve as a reminder that shoddy science, combined with overhyping of a little tested technology and premature partnerships with healthcare industry, can lead to bankruptcy and lawsuits.
