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Ovarian Cancer Survivors

This statement summarizes the U.S. Preventive Services Task Force (USPSTF) recommendation on screening for ovarian cancer and the supporting scientific evidence, and updates the 1996 recommendations contained in the Guide to Clinical Preventive Services, 2d ed. (1) In 1996, the USPSTF recommended against routine screening for ovarian cancer (D recommendation). (1) Since then, the USPSTF criteria to rate the strength of the evidence have changed. (2) Therefore, this recommendation statement has been updated and revised based on the current USPSTF methodology and rating of the strength of the evidence. Explanations of the current taskforce ratings and strength of overall evidence are given in Tables 1 and 2, respectively.

The complete information on which this statement is based, including evidence tables and references, is available in the brief evidence update (3) on this topic on the USPSTF Web site (http://www.preventiveservices. ahrq.gov). The recommendation statement and brief evidence update also are available in print from the Agency for Healthcare Research and Quality Publications Clearinghouse (telephone: 1-800-358-9295; e-mail: ahrqpubs@ahrq.gov). The recommendation also is posted on the Web site of the National Guideline Clearinghouse (http://www.guideline.gov).

This recommendation statement was first published in Ann Fam Med 2004;2:260-2.

Summary of Recommendation

The USPSTF recommends against routine screening for ovarian cancer. D recommendation.

The USPSTF found fair evidence that screening with serum CA-125 level or transvaginal ultrasound can detect ovarian cancer at an earlier stage than it can be detected in the absence of screening; however, the USPSTF found fair evidence that earlier detection would likely have a small effect, at best, on mortality from ovarian cancer. Because of the low prevalence of ovarian cancer and the invasive nature of diagnostic testing after a positive screening test, there is fair evidence that screening could likely lead to important harms. The USPSTF concluded that the potential harms outweigh the potential benefits.

Clinical Considerations

* There is no existing evidence that any screening test, including CA-125, ultrasonography, and pelvic examination, reduces mortality from ovarian cancer. Furthermore, existing evidence that screening can detect early-stage ovarian cancer is insufficient to indicate that this earlier diagnosis will reduce mortality.

* Because there is a low incidence of ovarian cancer in the general population (age-adjusted incidence of 17 per 100,000 women), screening for ovarian cancer is likely to have a relatively low yield. The great majority of women with a positive screening test will not have ovarian cancer (i.e., they will have a false-positive result). In women at average risk, the positive predictive value of an abnormal screening test is, at best, approximately 2 percent (i.e., 98 percent of women with positive test results will not have ovarian cancer).

* The positive predictive value of an initially positive screening test would be more favorable for women at higher risk. For example, the lifetime probability of ovarian cancer increases from about 1.6 percent in a 35-year-old woman without a family history of ovarian

cancer to about 5 percent if she has one relative and 7 percent if she has two relatives with ovarian cancer. If ongoing clinical trials show that screening has a beneficial effect on mortality rates, then women at higher risk are likely to experience the greatest benefit.

Discussion

Ovarian cancer is the fifth leading cause of cancer death among women in the United States, accounting for an estimated 25,400 new cases and 14,300 deaths in 2003. (4) Several risk factors are associated with ovarian cancer. Family history increases the risk for ovarian cancer: having one first- or second-degree relative with ovarian cancer increases risk by about threefold. (5) Carriers of the BRCA1 or BRCA2 gene mutations also are at increased risk. (6) The risk for developing ovarian cancer is reduced with oral contraceptive use and pregnancy of any duration. (7) Some studies have shown that postmenopausal women taking estrogen may be at increased risk for developing ovarian cancer. (8,9)

Most women with ovarian cancer have nonlocalized disease at the time of diagnosis. (4) A randomized controlled trial (RCT) using multimodal screening (CA-125 screening, followed by ultrasonography in patients with abnormally elevated levels) reported that 50 percent of patients with ovarian cancer in the screened group were in stage I, compared with only 5 percent in the control group. (3,10) This difference was not statistically significant. Two large cohort studies using transvaginal ultrasonographic screening reported that 59 to 65 percent of ovarian cancers were diagnosed in stage I. (11,12) However, there is no evidence that detecting earlier-stage tumors through screening leads to a decrease in ovarian cancer-specific mortality.

Establishing the true sensitivity of CA-125 or ultrasonography is limited by several factors. The studies assessing the accuracy of screening tests have used different thresholds to define an elevated CA-125 level and different lengths of clinical follow-up, and have included small numbers of patients. In women at average risk for ovarian cancer, using thresholds of 30 U per mL or 35 U per mL, the one-year follow-up sensitivity of CA-125 screening, followed by ultrasonography, has been reported to be about 80 percent; the specificity is nearly 100 percent. (13-15) However, using a similar CA-125 threshold for women at high risk for ovarian cancer, the sensitivity would be reduced to 50 percent. The estimated sensitivity of annual transvaginal ultrasonography at one-year follow-up is 88 percent (95 percent confidence interval [CI], 47 to 100 percent); the specificity is estimated to range from 97 to 99 percent. (16) There is conflicting evidence as to whether adding color Doppler imaging to ultrasonographic screening can reduce the rate of false-positive test results. (17,18) There are few data available to determine the sensitivity and specificity of successive rounds of screening.

There is a significant potential for harms associated with screening for ovarian cancer, although there are few data to assess the magnitude of harms from screening, such as needless surgery or increased anxiety. A study by the British Health Technology Assessment program estimated that screening a hypothetical cohort of 10,000 women aged 50 to 64 for ovarian cancer, using either annual CA-125 or twice-yearly transvaginal ultrasonography (assuming specificities of 97 and 93 percent, respectively), would result in 300 women (using CA-125) or 350 women (using ultrasonography) who do not have ovarian cancer being recalled each year for further assessment, resulting in potential distress and anxiety in otherwise healthy women. (16) Of these, 20 (using CA-125) or 65 (using ultrasonography) women without ovarian cancer would undergo surgery each year. For women at average risk for ovarian cancer, the positive predictive value of an abnormal screening test is, at best, approximately 2 percent. On the other hand, the potential benefits of screening (based on this model's optimistic assumption that earlier treatment leads to a 40 percent mortality reduction) would yield a maximum of four additional cancers detected per year and would result in 1.5 additional five-year survivors for each year of screening.

Although no RCT of screening for ovarian cancer with mortality outcomes in the general population has yet been complete& at least three such RCTs are currently in progress: the United Kingdom Collaborative Trial of Ovarian Cancer Screening; the National Institutes of Health Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial; and the European Randomized Trial of Ovarian Cancer Screening. (19-21)

Recommendations of Others

Routine screening for ovarian cancer is not recommended by any medical organization. The American Cancer Society states that women with a strong family history of this disease may be screened, but transvaginal ultrasonography and CA-125 are not recommended in women without known strong risk factors for ovarian cancer. (22) Instead of routine screening, the American College of Obstetricians and Gynecologists suggests that generalist obstetrician-gynecologists remain vigilant for the early signs and symptoms of ovarian cancer, such as abdominal or pelvic pain and unexplained weight loss, and that these symptoms be evaluated by pelvic examination, CA-125, or ultrasonography. (23) The Canadian Task Force on Preventive Health Care recommended against screening asymptomatic pre- and post-menopausal women in 1994. (24) The Canadian task force also found insufficient evidence to recommend for or against screening high-risk women with a family history of ovarian cancer, but noted that expert opinion suggested these women be referred to an academic health center for regular combination screening.

TABLE 1
USPSTF Recommendations and Ratings

The USPSTF grades its recommendations according to one of five
classifications (A, B, C, D, or I) reflecting the strength of
evidence and magnitude of net benefit (benefits minus harms).

A. The USPSTF strongly recommends that clinicians provide [the
   service] to eligible patients. The USPSTF found good evidence
   that [the service] improves important health outcomes and
   concludes that benefits substantially outweigh harms.

B. The USPSTF recommends that clinicians provide [the service] to
   eligible patients. The USPSTF found at least fair evidence that
   [the service] improves important health outcomes and concludes
   that benefits outweigh harms.

C. The USPSTF makes no recommendation for or against routine
   provision of [the service]. The USPSTF found at least fair
   evidence that [the service] can improve health outcomes but
   concludes that the balance of benefits and harms is too close to
   justify a general recommendation.

D. The USPSTF recommends against routinely providing [the service] to
   asymptomatic patients. The USPSTF found at least fair evidence
   that [the service] is ineffective of that harms outweigh benefits.

I. The USPSTF concludes that the evidence is insufficient to
   recommend for or against routinely providing [the service].
   Evidence that [the service] is effective is lacking, of poor
   quality, of conflicting, and the balance of benefits and harms
   cannot be determined.

USPSTF = U.S. Preventive Services Task Force.

TABLE 2
USPSTF Strength of Overall Evidence

The USPSTF grades the quality of the overall evidence for a service
on a three-point scale (good, fair, or poor).

Good: Evidence includes consistent results from well-designed,
      well-conducted studies in representative populations that
      directly assess effects on health outcomes.

Fair: Evidence is sufficient to determine effects on health outcomes,
      but the strength of the evidence is limited by the number,
      quality, or consistency of the individual studies;
      generalizability to routine practice; or indirect nature of the
      evidence on health outcomes.

Poor: Evidence is insufficient to assess the effects on health
      outcomes because of limited number or power of studies,
      important flaws in their design or conduct, gaps in the chain
      of evidence, or lack of information on important health
      outcomes.

USPSTF = U.S. Preventive Services Task Force.

REFERENCES

(1.) U.S. Preventive Services Task Force. Guide to clinical preventive services. 2d ed. Washington, D.C.: U.S Department of Health and Human Services, Office of Public Health and Science, Office of Disease Prevention and Health Promotion, 1996.

(2.) Harris RP, Helfand M, Woolf SH, Lohr KN, Mulrow CD, Teutsch SM, et al. Current methods of the U.S. Preventive Services Task Force: a review of the process. Am J Prev Med 2001;20(3 suppl):21-35.

(3.) Nelson HD, Westhoff C, Piepert J, Berg A. Screening for ovarian cancer: brief evidence update. Accessed online November 12, 2004, at: http://www.ahrq.gov/ clinic/3rduspstf/ovariancan/ovcanup.htm.

(4.) American Cancer Society. Cancer Facts and Figures 2003. Accessed online November 12, 2004, at: http://www. cancer.org/downloads/STT/CAFF2003PWSecured.pdf.

(5.) Kerlikowske K, Brown JS, Grady DG. Should women with familial ovarian cancer undergo prophylactic oophorectomy? Obstet Gynecol 1992;80:700-7.

(6.) Ford D, Easton DF. The genetics of breast and ovarian cancer. Br J Cancer 1995;72:805-12.

(7.) Whittemore AS, Harris R, Itnyre J. Characteristics relating to ovarian cancer risk: collaborative analysis of 12 US case-control studies. II. Invasive epithelial ovarian cancers in white women. Collaborative Ovarian Cancer Group. Am J Epidemiol 1992;136:1184-203.

(8.) Lacey JV Jr, Mink PJ, Lubin JH, Sherman ME, Troisi R, Hartge P, et al. Menopausal hormone replacement therapy and risk of ovarian cancer [published erratum appears in JAMA 2002;288:2544]. JAMA 2002;288:334-41.

(9.) Rodriguez C, Patel AV, Calle EE, Jacob EJ, Thun MJ. Estrogen replacement therapy and ovarian cancer mortality in a large prospective study of US women. JAMA 2001;285:1460-5.

(10.) Jacobs IJ, Skates SJ, MacDonald N, Menon U, Rosenthal AN, Davies AP, et al. Screening for ovarian cancer: a pilot randomised controlled trial. Lancet 1999;353:1207-10.

(11.) Sato S, Yokoyama Y, Sakamoto T, Futagami M, Saito Y. Usefulness of mass screening for ovarian carcinoma using transvaginal ultrasonography. Cancer 2000;89:582-8.

(12.) van Nagell JR Jr, DePriest PD, Reedy MB, Gallion HH, Ueland FR, Pavlik EJ, et al. The efficacy of transvaginal sonographic screening in asymptomatic women at risk for ovarian cancer. Gynecol Oncol 2000;77:350-6.

(13.) Jacobs I, Stabile I, Bridges J, Kemsley P, Reynolds C, Grudzinskas J, et al. Multimodal approach to screening for ovarian cancer. Lancet 1988;1:268-71.

(14.) Jacobs I, Davies AP, Bridges J, Stabile I, Fay T, Lower A, et al. Prevalence screening for ovarian cancer in postmenopausal women by CA 125 measurement and ultrasonography. BMJ 1993;306:1030-4.

(15.) Adonakis GL, Paraskevaidis E, Tsiga S, Seferiadis K, Lolis DE. A combined approach for the early detection of ovarian cancer in asymptomatic women. Eur J Obstet Gynecol Reprod Biol 1996;65:221-5.

(16.) Bell R, Petticrew M, Luengo S, Sheldon TA. Screening for ovarian cancer: a systematic review. Health Technol Assess 1998;2:i-iv,1-84.

(17.) Vuento MH, Pirhonen JP, Makinen JI, Laippala PJ, Gronroos M, Salmi TA. Evaluation of ovarian findings in asymptomatic postmenopausal women with color Doppler ultrasound. Cancer 1995;76:1214-8.

(18.) Kurjak A, Shalan H, Kupesic S, Kosuta D, Sosic A, Benic S, et al. An attempt to screen asymptomatic women for ovarian and endometrial cancer with transvaginal color and pulsed Doppler sonography. J Ultrasound Med 1994;13:295-301.

(19.) Gohagan JK, Prorok PC, Hayes RB, Kramer BS. The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial of the National Cancer Institute: history, organization, and status. Control Clin Trials 2000;21(6 suppl):251S-272S.

(20.) Prorok PC, Andriole GL, Bresalier RS, Buys SS, Chia D, Crawford ED, et al. Design of the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. Control Clin Trials 2000;21(6 suppl):273S-309S.

(21.) Jacobs IJ. European randomized trial of ovarian cancer screening (protocol). London: Wolfson Institute of Preventive Medicine, Department of Environmental and Preventive Medicine, 1995.

(22.) American Cancer Society. Detailed guide: ovarian cancer. Can ovarian cancer be found early? Accessed online November 12, 2004, at: http://www.cancer.org/ docroot/CRI/content/CRI_2_4_3X_Can_ovarian_cancer_be_found_early_33.asp.

(23.) ACOG Committee on Gynecologic Practice. The role of the generalist obstetrician-gynecologist in the early detection of ovarian cancer. Gynecol Oncol 2002;87:237-9.

(24.) Gladstone CQ. Screening for ovarian cancer. In: Canadian Task Force on the Periodic Health Examination. The Canadian guide to clinical preventive health care. Ottawa: Canada Communication Group, 1994:870-81.

Address correspondence to Ned Calonge, M.D., M.P.H., Chair, U.S. Preventive Services Task Force, c/o Program Director, USPSTF, Agency for Healthcare Research and Quality, 540 Gaither Rd., Rockville, MD 20850 (e-mail: uspstf@ahrq.gov).

The U.S. Preventive Services Task Force recommendations are independent of the U.S. government. They do not represent the views of the Agency for Healthcare Research and Quality, the U.S. Department of Health and Human Services, or the U.S. Public Health Service.

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