Simple ovarian cysts are very common in women and do not require additional ultrasound monitoring or surgical removal, according to a new study of more than 72,000 women and nearly 119,000 pelvic ultrasound examinations for a dozen years.
This study, a collaboration between UC San Francisco and Kaiser Permanente Washington, found that simple cysts are normal, very common in pre and postmenopausal women, and not associated with a higher risk of ovarian cancer. As a result, unless they are symptomatic, simple cysts can be safely ignored, the researchers found.
In contrast, complex cysts or dense ovarian masses are much rarer, but are associated with a higher risk of significantly developing malignant cancer, the authors report. This mass must be followed or surgery removed.
Paper published November 12, 2018 in JAMA Internal Medicine, shows changes in the way that simple cysts are usually monitored and sometimes treated.
"There is a lot of unnecessary medical supervision that goes on for simple cysts," said the corresponding author, Rebecca Smith-Bindman, MD, professor of UCSF in the Department of Radiology and Biomedical Imaging. He is also a professor in the department of Epidemiology and Biostatistics, and Obstetrics, Gynecology and Reproductive Medicine, and a member of the Philip R. Lee Health Policy Research Institute.
"Simple cysts are almost universally harmless, but because of concerns that they can store cancer precursors, they have often supervised and referred to obstetricians and oncologists," he said. "Our study found that simple symptoms of any size cysts should be considered normal findings in women of all ages and ignored."
Ovarian cancer is the fifth leading cause of cancer deaths among women in the US, with 22,000 newly diagnosed cases and 14,000 deaths, every year.
In the past two decades, increased use of transvaginal pelvic ultrasound has led to frequent identification of ovarian masses. Although most of these masses are benign, researchers and professional guidelines continue to recommend simple ongoing cyst surveillance, due to the poor prognosis of malignant ovarian cancer, and concerns over the small risk of cancer in a benign-looking mass.
This is the first study to measure the risk of ovarian cancer in large unselected populations, based on the characteristics of ultrasound ovarian mass, including simple cysts. The authors sought to identify features that would predict with high certainty whether the ovarian mass was benign and did not require supervision.
The study tracked 72,093 women who underwent pelvic ultrasound through Kaiser Permanente Washington between January 1997 and December 2008. About 75 percent were less than 50 years old.
During the study period, women underwent 118,778 pelvic ultrasound examinations. Among 54,452 women under 50, the researchers estimated that around 24 percent (12,957 women) were diagnosed with simple cysts and no cancer developed during follow-up. Of the 17,641 women aged 50 and older, about 13 percent (2,349 women) were diagnosed with simple cysts and only one was diagnosed with cancer.
In statistical analysis, the risk of developing cancer is approximately zero in women with simple cysts, regardless of the size of the cyst. This study identified 210 cases of ovarian cancer, almost all of which were seen in women with complex cystic masses.
Ultrasound accurately predicts the likelihood of cancer, which is likely to increase in women with complex cystic or solid ovarian masses, the authors said. They estimate that 6.5 percent of such post-menopausal women with mass will be diagnosed with ovarian cancer within three years. In contrast, women with simple ovarian cysts were not associated with a higher risk of cancer than those who had normal ovaries. The authors acknowledge the limitations, including that women with a previous history of cancer were not included in this study.
"One justification for monitoring simple cysts is imaging that may be inaccurate and may lose complex features," said Smith-Bindman, a member of UCSF Helen Diller Family Comprehensive Cancer Center. "This is not supported by our data. Cysts are interpreted as simple, even very large, not related to cancer.
"I understand why women and doctors don't want to misdiagnose ovarian cancer," he said. "Ovarian cancer is a devastating disease. But ovarian cancer does not appear on simple cysts and following a simple cyst with imaging will not result in an improvement in early detection of ovarian cancer. "
Author: Co-the author is Liina Poder, MD, from the UCSF Department of Biomedical Radiology and Imaging; and Eric Johnson, MS, and Diana L. Miglioretti, PhD from Kaiser Permanente Washington Health Research Institute. Miglioretti is also a professor at the University of California, Davis.
Funding: This study was supported by the National Cancer Institute giving R21CA131698 and K24CA125036.
Disclosure: There is no.
UC San Francisco (UCSF) is a leading university dedicated to promoting health throughout the world through advanced biomedical research, postgraduate education in life sciences and the health profession, and excellence in patient care. These include graduates of dentistry, medicine, nursing and pharmacy schools; a postgraduate division with well-known national programs in the fields of basic science, biomedicine, translation and population; and a superior biomedical research company. This also includes UCSF Health, which consists of three top-ranked hospitals – UCSF Medical Center and UCSF Benioff Children's Hospital in San Francisco and Oakland – as well as Langley Porter Mental Hospital and Clinic, UCSF Benioff Children, and Faculty Practices UCSF. UCSF Health has affiliations with hospitals and health organizations throughout the Bay Area. The UCSF Faculty also provides all medical care at the Zuckerberg San Francisco public hospital and Trauma Center, and the SF VA Medical Center. The UCSF Fresno Medical Education Program is the main branch of the University of California, San Francisco Medical School.