One reason for the knee-jerk testing of many physicians is defensive medicine. Even when such a dissertation about the risks of screening does occur, the patient cannot be held responsible for their decision, the physician (or training program, as in the case of the PSA that has been discussed in this blog) is held responsible for not making the recommendation, because the public perception is that there is no harm in testing.

I use the CA-125 example often. This one circulates on the internet every 2 years or so, that women should have screening CA-125 to detect ovarian cancer early. Of course the example case is someone with advanced disease, but that technicality is lost on the reader. Invariably, droves of women come in asking for a CA-125 test to detect ovarian cancer, because no other test will do it. It’s a poor test. Assume that it is done on an otherwise healthy person and is high (“positive”) – what now? Imaging studies are likely to be negative (that is the rationale for doing CA-125 – “it detects before imaging can”) – so what next? Exploratory laparoscopy/laparotomy – for a test that is insensitive and unspecific. Here is one citation:

Moss, EL, el al. The role of CA125 in clinical practice. J Clin Pathol. 2005 Mar;58(3):308-12.

which abstract concludes:

These results confirm the high false positive rate and poor sensitivity and specificity associated with CA125. The substantial inappropriate usage of CA125 has led to results that are useless to the clinician, have cost implications, and add to patient anxiety and clinical uncertainty.

Wait – it will come around again. Snopes.com has a story on the letter that circulates: http://www.snopes.com/toxins/ca125.htm

Pap smear is currently recommended every 3 years (after 3 consequitive negative scans) yet most ObGyns keep doing them every year even for women whose lack of sex life puts them at very low risk.

Experts still argue about whether benefits of mammograms especially for women in their 40s are greater than risks, but if I, after carefully reading analysis of the available studies, articles (in medical journals such as BMJ and websites like NCI) on the subject, decide that I don’t want them (because for me 1 in 1700 chance after 10 mammograms that it’ll save my life based on optimistic view of the studies – interestingly though that the study that showed no benefit is both more recent and most reviewed – is not worth for me the 50% chance of false positive, 18% chance of a biopsy and a tangible probability of being treated for something that would’ve never threatened my life), I’d be called irresponsible and harassed and scared by misleading statistics (using relative risk instead of absolute risk as well as hypothetical life-time risk instead of 10-year risk)and pressured.
I think we’ve been lead to believe that early detection is always beneficial, that every second counts, and that there are no harms associated with screening. Media is mostly to blame, but doctors share the blame as well. Had we, the public, been given the fuller picture right away, maybe the perception would’ve been different.

But that takes time, and people aren’t a herd of cows.
They are individuals who have an interest in getting a best-case -scenario for themselves.

Screening undoubtedly will help dectect cancer earlier. That alone is a benefit to patients for a multitude of reasons, including wise planning, making the most of good days ahead, setting priorities.

Even if folks who find early cancer through screening won’t get any extra time (which is doubtful, they probably will get extra time, especially as experience in the treatment of early cancer becomes more common).

The only significant downside is the “incidentaloma” issue – but patients can make an informed choice.

http://www.medicinenet.com/script/main/art.asp?articlekey=47717

It is intuitive that that should be the case, but the evidence is not there.

Kevin

Nobody thinks that spiral CT will reduce his or her chance of lung cancer. They think it might increase the chances any lung cancer contracted will be found at an earlier stage of progression, when the cancer is still small and occult and potentially more treatable and survivable.