No one wants to miss ovarian cancer especially in its early stages when you have a chance of successful treatment.
But should we be regularly monitoring women who have had a simple ovarian cyst detected on ultrasound, as most guidelines recommend to avoid missing this particularly deadly cancer?
That is what US researchers investigated in a nested case controlled study, recently published in JAMA.
The study was based on a cohort of adult women from the Kaiser Permanente Washington health care system who had had a pelvic ultrasound at some stage over a 12-year period starting in 1997, and looked at the association of the ultrasound finding with the risk of being diagnosed with ovarian cancer within three years.
On analysing the data from the 72,000 women who underwent the investigation, the first finding was that ovarian cysts were very common, particularly simple ovarian cysts, occurring in more than 15,000 women. Simple cysts were detected in almost one in four women aged younger than 50, and just over one in 12 women aged 50 and over.
Complex cyst structures were far less common, which is fortunate as the study also confirmed that most of the 212 women who were eventually diagnosed with ovarian cancer had a complex cyst structure on ultrasound.
According to their analysis, the detection of a complex cystic ovarian mass on ultrasound increased the likelihood of cancer eight-fold, and if they were 50 or over and found to have ascites as well, the finding was practically diagnostic with the likelihood of having ovarian cancer being over 70 times greater than normal.
Ultrasound detection of solid masses was not as dangerous a finding, but the one in ten association with ovarian cancer certainly warranted further investigation.
But what of the women found to have a simple cyst on ultrasound? How many of them went on to be diagnosed with ovarian cancer? Well, among those aged under 50 – none! And among the older women only one – and the researchers suspect that the simple cyst found in this case was, in fact an incidental finding.
As the study authors point out, this finding shouldn’t be surprising as it is well-known that ‘simple cysts are almost universally benign.’
But the majority of guidelines still recommend on-going surveillance, mainly because of a reluctance to make a definitive diagnosis on the basis of the ultrasound appearance or interpretation alone.
“One of the justifications for the surveillance of simple cysts is that imaging may be inaccurate and might miss complex features,” the researchers explain.
But such concerns are not warranted according to this study. What’s more, the authors suggest the constant monitoring of these benign cysts may in fact not only be useless but may cause harm.
“While surveillance may not seem harmful, there is a growing realisation across all areas of medicine that unnecessary imaging is associated with morbidity, including wasted time, false-positive results, over diagnosis, unnecessary surgery and anxiety,” the study authors concluded.
Smith-Bindman R, Poder L, Johnson E, Miglioretti DL. Risk of Malignant Ovarian Cancer Based on Ultrasonography Findings in a Large Unselected Population. JAMA Intern Med. Published online November 12, 2018. doi:10.1001/jamainternmed.2018.5113.