Incidental ovarian cysts: When to reassure, when to reassess, when to refer
ABSTRACTOvarian cysts are commonly found on imaging done for other reasons. Proper triage will decrease unnecessary procedures and worry while obtaining the best survival benefit for those ultimately found to have cancer.
KEY POINTS
- Incidentally discovered ovarian cysts are common and most are benign, but a minority can represent ovarian cancer, which is difficult to detect before it has spread and therefore often has a poor prognosis.
- Patients can be reassured if they are postmenopausal and have a simple cyst smaller than 1 cm or if they are premenopausal and have a simple cyst smaller than 5 cm.
- Reassess with yearly ultrasonography in very low-risk situations and with repeat ultrasonography in 6 to 12 weeks if the diagnosis is not clear but is likely benign.
- Refer to a gynecologist in cases of symptomatic cysts, cysts larger than 6 cm, and cysts that require ancillary testing.
- Refer to a gynecologic oncologist for findings worrisome for cancer such as thick septations, solid areas with flow, ascites, evidence of metastasis, or high cancer antigen 125 levels.
Ovarian cysts, sometimes reported as ovarian masses or adnexal masses, are frequently found incidentally in women who have no symptoms. These cysts can be physiologic (having to do with ovulation) or neoplastic—either benign, borderline (having low malignant potential), or frankly malignant. Thus, these incidental lesions pose many diagnostic challenges to the clinician.
The vast majority of cysts are benign, but a few are malignant, and ovarian malignancies have a notoriously poor survival rate. The diagnosis can only be obtained surgically, as aspiration and biopsy are not definitive and may be harmful. Therefore, the clinician must try to balance the risks of surgery for what may be a benign lesion with the risk of delaying diagnosis of a malignancy.
In this article we provide an approach to evaluating these cysts, with guidance on when the patient can be reassured and when referral is needed.
THE DILEMMA OF OVARIAN CYSTS
Ovarian cysts are common
Premenopausal women can be expected to make at least a small cyst or follicle almost every month. The point prevalence for significant cysts has been reported to be almost 8% in premenopausal women.1
Surprisingly, the prevalence in postmenopausal women is as high as 14% to 18%, with a yearly incidence of 8%. From 30% to 54% of postmenopausal ovarian cysts persist for years.2,3
Little is known about the cause of most cysts
Little is known about the cause of most ovarian cysts. Functional or physiologic cysts are thought to be variations in the ovulatory process. They do not seem to be precursors to ovarian cancer.
Most benign neoplastic cysts are also not thought to be precancerous, with the possible exception of the mucinous kind.4 Ovarian cysts do not increase the risk of ovarian cancer later in life,3,9 and removing benign cysts has not been shown to decrease the risk of death from ovarian cancer.10
Most ovarian cysts and masses are benign
Simple ovarian cysts are much more likely to be benign than malignant. Complex and solid ovarian masses are also more likely to be benign, regardless of menopausal status, but more malignancies are found in this group.
With any kind of mass, the chances of malignancy increase with age. Children and adolescents are not discussed in this article; they should be referred to a specialist.
Ovarian cancer often has a poor prognosis
This “silent” cancer is most often discovered and treated when it has already spread, contributing to a reported 5-year survival rate of only 33% to 46%.11–13 Ideally, ovarian cancer would be found and removed while still confined to the ovary, when the 5-year survival rate is greater than 90%.
Unfortunately, there does not seem to be a precursor lesion for most ovarian cancers, and there is no good way of finding it in the stage 1 phase, so detecting this cancer before it spreads remains an elusive goal.11,14
Surgery is required to diagnose difficult cases
There is no perfect test for the preoperative assessment of a cystic ovarian mass. Every method has drawbacks (Table 1).15–18 Therefore, the National Institutes of Health estimates that 5% to 10% of women in the United States will undergo surgical exploration for an ovarian cyst in their lifetime. Only 13% to 21% of these cysts will be malignant.5
ASSESSING AN INCIDENTALLY DISCOVERED OVARIAN MASS
Certain factors in the history, physical examination, and blood work may suggest the cyst is either benign or malignant and may influence the subsequent assessment. However, in most cases, the best next step is to perform transvaginal ultrasonography, which we will discuss later in this paper.
History
Age is a major risk factor for ovarian cancer; the median age at diagnosis is 63 years.9 In the reproductive-age group, ovarian cysts are much more likely to be functional than neoplastic. Epithelial cancers are rare before the age of 40, but other cancer types such as borderline, germ cell, and sex cord stromal tumors may occur.19
In every age group a cyst is more likely to be benign than malignant, although, as noted above, the probability of malignancy increases with age.
Symptoms. Most ovarian cysts, benign or malignant, are asymptomatic and are found only incidentally.
The most commonly reported symptoms are pelvic or lower-abdominal pressure or pain. Acutely painful conditions include ovarian torsion, hemorrhage into the cyst, cyst rupture with or without intra-abdominal hemorrhage, ectopic pregnancy, and pelvic inflammatory disease with tubo-ovarian abscess.
Some patients who have ovarian cancer report vague symptoms such as urinary urgency or frequency, abdominal distention or bloating, and difficulty eating or early satiety.20 Although the positive predictive value of this symptom constellation is only about 1%, its usefulness increases if these symptoms arose recently (within the past year) and occur than 12 days a month.21
Family history of ovarian, breast, endometrial, or colon cancer is of particular interest. The greater the number of affected relatives and the closer the degree of relation, the greater the risk; in some cases the relative risk is 40 times greater.22 Breast-ovarian cancer syndromes, hereditary nonpolyposis colorectal cancer syndrome, and family cancer syndrome, as well as extremely high-risk pedigrees such as BRCA1, BRCA2, and Lynch syndrome, all place women at significantly higher risk. Daughters tend to develop cancer at a younger age than their affected mothers.
However, only 10% of ovarian cancers occur in patients who have a family history of it, leaving 90% as sporadic occurrences.
Other history. Factors protective against ovarian cancer include use of oral contraceptives at any time, tubal ligation, hysterectomy, having had children, breastfeeding, a low-fat diet, and possibly use of aspirin and acetaminophen.23,24
Risk factors for malignancy include advanced age; nulliparity; family history of ovarian or breast cancer; personal history of breast cancer; talc use; asbestos exposure; white ethnicity; pelvic irradiation; smoking; alcohol use; possibly the previous use of fertility drugs, estrogen, or androgen; history of mumps; urban location; early menarche; and late menopause.24
