Subjects: R and D
Cancer of the ovary is a particularly nasty disease. It often remains asymptomatic until it has reached an advanced, incurable stage, and scientists have been unable to develop an effective screening test for the disease like the ones in widespread use for cancers of the breast and cervix.
The dismal status of ovarian cancer screening was underscored a year ago when an NIH-sponsored study showed that over 70% of cancers detected by transvaginal ultrasound and CA 125 biomarker testing—the two best ovarian screening tests we’ve got—had reached stage III or IV at the time the patients screened positive. That’s about what happens when women aren’t screened at all.
That wasn’t the worst of it, however. In just the first year of that screening program, positive test results obligated 566 surgical procedures which uncovered only 18 cancers. That’s an awful lot of unnecessary surgery and associated morbidity right there. Things were no better on the false-negative side of things. Overall, 89 cases of ovarian cancer were diagnosed during the NIH study, and a third of them had been missed by both screening modalities.
What’s New? The NIH study didn’t evaluate the impact of screening on ovarian cancer mortality, but a recent study by Laura Havrilesky and colleagues at Duke did indeed address the point. Sadly, the results were abysmal.
Havrilesky’s team developed a modified a Markov model to characterize the natural history of ovarian cancer, and used it to show that mortality would fall by a paltry 11% if a widespread screening program (in this case, CA 125 biomarker testing followed by pelvic ultrasound imaging for women with abnormal results) was put into place.
The scientists emphasized that the protean nature of ovarian cancer—not just its tendency to remain asymptomatic until an advanced stage—was a huge challenge in developing an effective screening tool. According to their analysis, some ovarian cancers tend to grow slowly, taking nearly 3 years before progressing to an advanced stage. Other ovarian cancers are more aggressive, reaching an advanced stage after only 13 months.
“If we assume ovarian cancers grow and spread at different rates, the best screening strategy available will only reduce the number of women dying from the cancer by 11%,” Havrilesky said in a press release. “This is partially because the slower growing cancers are more likely to be caught by a screening test.”
The authors didn’t exactly throw up their hands in disgust at the poor prospects for ovarian screening, but they did suggest that policy makers consider directing funds towards prevention and treatment of the disease, and away from screening.
That said, most experts do recommend routine screening for ovarian cancer in women that have a family history of the disease and in those who carry genes known to increase the risk of developing it. As always, women with questions about these issues should consult their doctors.
Havrilesky’s write-up appears in Cancer.