Early Detection: screening effectiveness

May 4th, 2009 · No Comments

Early Detection: screening effectiveness

A recent article was published on the effectiveness of screening for the early detection of ovarian cancer.  This was published in the journal called Lancet Oncology in April 2009.

In this study, 202,638 women who were aged between 50 and 74 years old were followed on this study from 2001 through 2005. Because not all the women were put on the study at the same time, the final analysis of this trial is supposed to end in 2014.  However, some results were published in this recent article. The women were split into three groups randomly: either routine follow-up (meaning no regular screening tests), transvaginal ultrasound, or transvaginal ultrasound and CA125 measurements. The patients were randomized via the flip of a coin in a 2:1:1 manner meaning that 50% of them randomly were assigned to the no screening arm and 25% each were put into the ultrasound only or ultrasound and CA125 group.

What the study found was in these over 200,000 women who were followed in this study, 58 invasive ovarian cancers were detected in the screening groups, and 24 of these (44%) were stage I cancers; the remaining cancers were stage III or IV.  The fact that 44% of the early detected cancers were in fact early stage is certainly encouraging.

So, this news did make some splash initially, but has not prompted a change in how we screen–which is no screening at this time.  Why?  For a number of reasons…. Firstly, in the ultrasound group, for each cancer that was detected, 35 surgeries were necessary, and for each cancer detected in the ultrasound + CA125 group, 3 surgeries had to be performed. So, a lot of unnecessary surgery was done.  However, the surgeries that proved benign possibly could be lessened if radiologists had better criteria for what is a suspicious mass and what is benign; as sometimes these distinctions are hard to judge. In this study, doctors were also not given any guidance about when to intervene and to do surgery on a mass detected via ultrasound.

I still think that a blood test (or a urine test) that is more accurate than the CA125 is going to ultimately be the better way to screen for ovarian cancer than using an ultrasound.  Many countries do not have  gynecological ultrasound and the time to detect the ovarian cancer is when it’s not even visible on ultrasound. Also the radiologist needs to have certain criteria found on the ultrasound to sound an alarm that the observed changes on the ultrasound really mean something; or else, a lot of unnecessary surgeries
will be performed. This study collected over 350,000 blood tests on these patients, and these samples may be ultimately able to lead to a better CA125 or blood tests done in addition to the CA125.

Have a good May!

Ursula Matulonis

Tags: The Doctor's Corner

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