That is the million dollar question floating around the healthcare world, and particularly the cancer world. For every study heralding the benefits of screening, there’s another one disparaging it as crockery.
Moments after last month’s New England Journal of Medicine study came out arguing for the utility of colonoscopies in preventing cancer deaths, people began referencing the National Cancer Institute’s studies which didn’t find a link between prostate and ovarian cancer screening on the one hand, and reduced mortality on the other.
Is screening just a veiled attempt for pharma to accrue more patients? Or is it a way of finding bona fide sick patients and treating them before their disease is untreatable? The only thing certain is that the jury’s still out, and it will take more time, studies and evidence generation before we get more clarity on screening.
Cancer screening — not one but many diseases
The crux of the controversy is in the name ‘cancer’ itself. When viewed as an aggregate, cancer has not appeared to outwit screening practices. But as we increasingly understand, cancer is not one disease, but many.
It is only when we look at screening in terms of individual cancers that the real picture begins to emerge. On the one hand we have tumours such as cervical cancer, whose screening practices have had particularly high rates of success thanks to the introduction of the pap smear. Indeed, in the UK it is estimated that 4500 lives are saved annually thanks to screening practices and in the US, such practices have meant that cervical cancer has slipped from one of the most common cancers to the eighth on the list.
On the other hand, we have the example of prostate cancer, which has not fared so well despite the introduction of the PSA test and has acted as a lightning rod for the overscreening debate. This debate came to the fore after the U.S. Preventive Services Task Force recommended against PSA screening tests due to a lack of certainty that the test actually does any good. That the test can lead to over treatment and unnecessary surgery, and related anxiety, has caused many to wonder if it ultimately does more harm than good. Given that there’s no other available screening alternative at this point it’s not altogether surprising that PSA testing continues to be relied on so heavily, despite the controversy and lack of consensus on its benefits. Yet, it is imperative that a better test is developed and it is especially important to get this right as prostate cancer is one of the more variable cancers; running the gamut from a relatively mild form, which is the majority of cases, to an incredibly aggressive and invasive form, prone to painful bone lesions.
Although our understanding of the manifold variety of different diseases within the broader umbrella term of cancer is pretty good – and improving rapidly – we are only just beginning to understand how this complexity affects policy and practice. .
Progress being made
Undoubtedly, progress is being made in this regard. For instance, we now look for HER2 in breast cancer as an overabundance of this receptor signals a more aggressive, destructive and fast moving cancer. For similar reasons the BRCA gene is sought, as this increases breast and ovarian cancer risks. Yet, this progress still trails behind the progress being made in cancer imaging. This means that although a ‘cancer’ may be found, how to treat it is still not known.
I think these questions will continue to plague the healthcare world until the understandings of the genetic and molecular mechanisms of cancer catches up with rapid advances in screening. Only then will we know when it’s appropriate to act and how to act. The question is – who should conduct the testing to improve this understanding…and perhaps more importantly, who is going to pay for it?