Monday, December 12, 2016

Ovarian Cancer Screening

Betsy Neisner sent me some links to interesting articles from a  continuing education webpage.

Here's one of the articles I read and I thought I'd share with you.

There are several more I will be posting.

If you are interested the website is called "MyCME". Just google it!

Ovarian Cancer Screening Study Falls Short
Significant mortality benefit only in subgroup analysis
Staff Writer, MedPage Today
December 17, 2015
The largest-ever screening study for ovarian cancer showed a modest reduction in the risk of dying of the cancer after more than a decade of follow-up, but failed to demonstrate a significant difference from no screening.

The primary analysis showed annual risk reductions of 15% and 11% with the two different methods of screening evaluated in the trial. Neither difference achieved statistical significance versus no screening. A prespecified analysis limited to patients screened with both a blood test and ultrasound (using different statistical methods) did yield a significant 20% annual reduction in ovarian cancer mortality risk.

Follow-up will continue in the trial to determine more precisely the magnitude of mortality reduction -- which could increase or decrease at this point -- and whether routine screening in the general population is cost effective, Ian Jacobs, MD, of University College London, and co-authors reported in The Lancet.

The preliminary results showed that 641 women would have to be screened with an assay for the cancer-related protein CA-125 plus transvaginal ultrasound to prevent one ovarian cancer death. The results also showed a small but clinically significant risk of harm, as 14 women with false-positive screening results had surgery that revealed no evidence of cancer. Complications occurred in 3.1% of the patients who underwent surgery.
The results will do little to inform the debate on screening average-risk women, said Don Dizon, MD, of Massachusetts General Hospital Cancer Center and a clinical expert for the American Society of Clinical Oncology.
"I'm underwhelmed by the results," Dizon told MedPage Today. "I think the summary of the study that was distributed in advance was a bit misleading. It's a hopeful study, regarding the benefits of screening, but the picture is still incomplete. If anything, it should spur on research, but it is by no means a green light to start screening the general population."
The U.S. Preventive Services Task Force has recommend against routine screening of women who have an average risk of ovarian cancer. The Centers for Disease Control and Prevention also does not support ovarian cancer screening and declined to comment on the British study.

The authors of a commentary that accompanied the article by Jacobs, et al, said the focus should be on determining how to maximize the benefits of available screening tools.
"If only 59% of ovarian cancer cases are detected by screening plus ultrasound, we will need to focus on why and how screening ... still has a significant, but delayed survival effect," said Rene Verheijen, MD, and Ronald Zweemer, MD, of the Utrecht Medical Center in The Netherlands. "Trying to unravel the mechanism behind this effect so that it can be improved should have high priority."

A majority of women with ovarian cancer have advanced disease at diagnosis, and 5-year survival for advanced disease is 40% or less. Most women have no symptoms preceding diagnosis of ovarian cancer, fueling interest in methods of early diagnosis.
Jacobs and co-authors reported initial findings from the U.K. Collaborative Trial of Ovarian Cancer Screening involving more than 200,000 women ages 50 to 74. Investigators at 13 centers randomized 50,640 to annual multimodality screening, 50,639 to annual screening by ultrasound only, and 101,359 to no screening. The primary endpoint was ovarian cancer mortality.
Screening ended Dec. 31, 2011, and the trial had a median follow-up of 11.1 years (maximum of 14 years). Patients in the multimodality screening group underwent a cumulative total of 345,570 screens, and the ultrasound group accumulated 327,775 screens.

By individual screening methods, the analysis showed a 15% (95% CI -3% to +30%, P=0.10) reduction in the risk of ovarian cancer death in the multimodality arm versus no screening and 11% (95% CI -7% to +27%, P=0.21) in the ultrasound group. A prespecified alternative method of statistical analysis (Royston-Parmar flexible parametric model), limited to the multimodality group, did show a statistically significant 20% reduction in the risk of ovarian cancer death after excluded women who had ovarian cancer at enrollment(95% CI -2% to +40%, P=0.021).
Most of the mortality benefit occurred during the later years of follow-up: 8% during years 0 to 7 versus 23% during years 7 to 14 in the multimodality group and 2% versus 21% in the ultrasound group.
"In retrospect, it would have been preferable to specify a primary analysis that was weighted to reflect the predictable delay in mortality reduction in a screening trial of this type," the authors said in their discussion.
"The main limitation of this trial was our failure to anticipate the late effect of screening in our statistical design," they added.

The late benefit perplexed Dizon.
"When you think about the benefit of screening, my understanding is that it should be realized earlier, rather than later,” he said. "When you stop screening [in a randomized trial], you're going to get cancers in both arms, and it may mask a survival advantage of screening, unless it's life long."

The basis for thinking the benefit might increase with longer follow-up is equally unclear, particularly if women decide to stop being screened, Dizon added.

1 comment:

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