Feasibility study of a randomised trial of ovarian cancer screening

Risks and benefits of screening asymptomatic women for ovarian cancer: a systematic review and meta-analysis

OBJECTIVE

We performed a systematic review and meta-analysis to quantify risks and benefits of screening asymptomatic women for ovarian cancer.

METHODS

We searched MEDLINE, EMBASE, CINAHL, and Cochrane CENTRAL, without language restrictions, from January 1, 1979 to February 5, 2012. Eligible studies randomly assigned asymptomatic women to screening or usual care. Two reviewers independently screened studies for eligibility, extracted data using a standardized, piloted extraction form, and assessed bias and strength of inference for each outcome using the GRADE framework. Chance-corrected agreement was calculated at each step, and disagreements were resolved through consensus.

RESULTS

Ten randomized trials proved eligible. Screening did not reduce all-cause mortality (relative risk (RR)=1.0, 95% confidence interval (CI) 0.96-1.06), ovarian cancer specific mortality (RR=1.08, 95% CI 0.84-1.38), or risk of diagnosis at an advanced stage (RR of diagnosis at FIGO stages III-IV=0.86, 95% CI 0.68-1.11). Transvaginal ultrasound resulted in a mean of 38 surgeries per ovarian cancer detected (95% CI 15.7-178.1) while screening with CA-125 led to 4 surgeries per ovarian cancer detected (95% CI 2.7-4.5). Surgery was associated with severe complications in 6% of women (95% CI 1%-11%). Quality of life was not affected by screening; however, women with false-positive results had increased cancer-specific distress compared to those with normal results (odds ratio (OR)=2.22, 95% CI 1.23-3.99).

CONCLUSIONS

Screening asymptomatic women for ovarian cancer does not reduce mortality or diagnosis at an advanced stage and is associated with unnecessary surgery.

Current management strategies for ovarian cancer

Epithelial ovarian cancer originates in the layer of cells that covers the surface of the ovaries. The disease spreads readily throughout the peritoneal cavity and to the lymphatics, often before causing symptoms. Of the cancers unique to women, ovarian cancer has the highest mortality rate. Most women are diagnosed as having advanced stage disease, and efforts to develop new screening approaches for ovarian cancer are a high priority. Optimal treatment of ovarian cancer begins with optimal cytoreductive surgery followed by combination chemotherapy. Ovarian cancer, even in advanced stages, is sensitive to a variety of chemotherapeutics. Although improved chemotherapy has increased 5-year survival rates, overall survival gains have been limited because of our inability to eradicate all disease. Technologic advances that allow us to examine the molecular machinery that drives ovarian cancer cells have helped to identify numerous therapeutic targets within these cells. In this review, we provide an overview of ovarian cancer with particular emphasis on recent advances in operative management and systemic therapies.

Update on ovarian cancer screening

PURPOSE OF REVIEW

Epithelial ovarian cancer is usually diagnosed in the advanced stage and carries a poor prognosis. When detected at an early stage, the 5-year survival rate is 90%. Despite the availability of various diagnostic tools for ovarian cancer screening, high levels of sensitivity and specificity are not achievable. There is therefore an ongoing need to identify new screening tests and strategies that should be readily available, relatively noninvasive, and achieve high sensitivity, specificity, and positive and negative predictive values.

RECENT FINDINGS

Our review focuses on various screening technologies including serum biomarkers, transvaginal ultrasonography as well as multimodality screening that can be used for early detection of ovarian cancer. The efficacy of different screening tools is discussed along with the efforts made to improve sensitivity, specificity and positive predictive value. The initial results of two large population-based screening studies are presented.

SUMMARY

An optimal screening test with high levels of sensitivity and specificity is indispensable for early detection of ovarian cancer. Serological screening with serum biomarkers (serum proteins and autoantibodies) can be used as a first-line screening test. In combination with TVS or color-flow Doppler imaging, this may prove very effective in early detection of ovarian cancer.

Ovarian cancer

Ovarian cancer accounts for 4% of all cancers in women and is the leading cause of death from gynaecologic malignancies. Because early-stage ovarian cancer is generally asymptomatic, approximately 75% of women present with advanced disease at diagnosis. Survival is highly dependent on stage of disease: 5-year survival in patients with early-stage is 80-90% compared to 25% for patients with advanced-stage disease. For all patients, a comprehensive surgical staging should be performed to obtain the histological confirmation of diagnosis and to evaluate the extent of disease. Patients with early-stage should both be optimally staged and be treated with adjuvant platinum-based chemotherapy if they have a medium or high-risk tumour. For advanced disease the currently recommended management is primary cytoreductive surgery followed by platinum-paclitaxel combination chemotherapy. Appropriate salvage therapy is based on the timing and nature of recurrence and the extent of prior chemotherapy. Surgical resection should be considered in patients with long-term remission, especially in those with isolated recurrences and good performance status. Platinum-based combination represents the standard second-line chemotherapy in patients with platinum-sensitive relapsed ovarian cancer. Salvage chemotherapy in platinum-refractory patients usually results in low response rates and short survival.

Screening for Ovarian Cancer

The efficacy of ovarian cancer screening remains to be proven. Advances in ultrasound and tumor marker technology, combined with complex statistical analysis have facilitated 2 large ongoing randomized controlled trials of screening which are powered to determine the impact on mortality. Serum proteomics seems to be a promising area for biomarker discovery, but requires more rigorous validation before it can be used in clinical trials. Current screening tests, clinical trials in the general and high-risk populations, screening acceptability and costs are reviewed in this article.

Screening for ovarian cancer in the general population

Screening for ovarian cancer in the general population presents several unique challenges. Without a clearly identified premalignant state, efforts have focused on detection of early stage disease. Towards this end, investigators have focused on the use of serum markers and transvaginal ultrasound. CA125 determination is the most reliable serum marker in use, and utilization of serial measurements to calculate risk of cancer appears to have greater utility than evaluation of a single value. Multimodality screening focuses on combining serial CA125 measurement with transvaginal ultrasound follow-up for those with abnormal values. Large prospective trials, such as the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), are currently underway to assess the impact of various screening strategies on mortality, and to evaluate feasibility, acceptability, and morbidity of screening. Future research efforts will undoubtedly focus on promising techniques to examine the serum proteosome for patterns to identify early ovarian cancer.

Screening postmenopausal women for ovarian cancer: a systematic review

OBJECTIVES

To assess ovarian cancer screening in asymptomatic, general-risk postmenopausal women. Outcomes of interest were the screening tests assessed (predictive values, sensitivity, and specificity), the stage of screen-detected disease at diagnosis, psychological effects of screening, and survival.

METHODS

MEDLINE, CANCERLIT, and the Cochrane Library databases were searched to June 2003 using the terms "ovarian," "cancer," "neoplasms," "screening," "clinical trial," "meta-analysis," and "systematic review." Studies were included if they were clinical trials, meta-analyses, or systematic reviews that evaluated tests used to detect ovarian cancer in asymptomatic women in the general population. Studies investigating women at increased risk for ovarian cancer (e.g., family history) and those with symptoms suggestive of ovarian cancer were excluded.

TABULATION, INTEGRATION, AND RESULTS

Seventeen prospective cohort studies and 3 pilot randomized controlled trials were included in this review. Screening tests for cancer antigen 125 (CA125) and ultrasound had low positive predictive values, resulting in healthy women being recalled and a false-positive rate of 0.01% to 5.8%. Of every 10,000 women participating in an annual screening program with CA125 for 3 years, 800 will have an ultrasound scan because of an elevated CA125, 30 will undergo surgery because of an abnormal ultrasound, and 6 will have ovarian cancer detected at surgery (3 will be diagnosed at early-stage disease and have a chance of a cure).

CONCLUSION

There is insufficient evidence to support the introduction of screening for ovarian cancer in the asymptomatic general-risk postmenopausal population. Screening is associated with increased rates of surgery and patient anxiety.

Biology of Epithelial Ovarian Cancer: Implications for Screening Women at High Genetic Risk

Purpose

Our aim was to analyze the clinicopathologic features of screen-detected ovarian cancers identified in women, either at general population risk or high genetic risk of ovarian cancer, who have participated in screening studies.

Methods

Studies published between 1988 and April 2003 were categorized by the population screened and the primary screening modalities used. Each report was examined with reference to the histologic type, stage, and grade of screen-detected cancers. Reports of studies of prophylactically removed ovaries from women at high risk of ovarian cancer were also reviewed.

Results

Of the stage I tumors detected by screening women at population risk, almost half were borderline ovarian tumors, granulosa-cell tumors, or germ-cell tumors, which is disproportionate to their frequency. Furthermore, of the stage I invasive epithelial cancers diagnosed in women at population risk, the majority were endometrioid, clear-cell, and mucinous histologic subtypes. Most ovarian cancers that occur in women at high genetic risk are high-grade serous cancers, and these are infrequently screen detected at an early stage.

Conclusion

The clinicopathologic features of screen-detected ovarian cancers suggest that screening may not reduce mortality in women at increased genetic risk. Prospective screening studies are required in genetically high-risk populations to answer this important question. Women electing surveillance should be aware of the lack of proven benefit and the low likelihood of detecting early stage serous cancers. Bilateral salpingo-oophorectomy appears to be the most effective approach to decrease the risk of ovarian cancer and thereby reduce mortality in high-risk women.

Progress and challenges in screening for early detection of ovarian cancer

Ovarian cancer is characterize by few early symptoms, presentation at an advanced stage, and poor survival. As a result, it is the most frequent cause of death from gynecological cancer. During the last decade, a research effort has been directed toward improving outcomes for ovarian cancer by screening for preclinical, early stage disease using both imaging techniques and serum markers. Numerous biomarkers have shown potential in samples from clinically diagnosed ovarian cancer patients, but few have been thoroughly assessed in preclinical disease and screening. The most thoroughly investigated biomarker in ovarian cancer screening is CA125. Prospective studies have demonstrated that both CA125 and transvaginal ultrasound can detect a significant proportion of preclinical ovarian cancers, and refinements in interpretation of results have improved sensitivity and reduced the false-positive rate of screening. There is preliminary evidence that screening can improve survival, but the impact of screening on mortality from ovarian cancer is still unclear. Prospective studies of screening are in progress in both the general population and high-risk population, including the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), a randomized trial involving 200,000 postmenopausal women designed to document the impact of screening on mortality. Recent advances in technology for the study of the serum proteome offer exciting opportunities for the identification of novel biomarkers or patterns of markers that will have greater sensitivity and lead time for preclinical disease than CA125. Considerable interest and controversy has been generated by initial results utilizing surface-enhanced laser desorption/ionization (SELDI) in ovarian cancer. There are challenging issues related to the design of studies to evaluate SELDI and other proteomic technology, as well as the reproducibility, sensitivity, and specificity of this new technology. Large serum banks such as that assembled in UKCTOCS, which contain preclinical samples from patients who later developed ovarian cancer and other disorders, provide a unique resource for carefully designed studies of proteomic technology. There is a sound basis for optimism that further developments in serum proteomic analysis will provide powerful methods for screening in ovarian cancer and many other diseases.

Screening for ovarian cancer

There has been considerable interest in the prospect of early detection of ovarian cancer through screening asymptomatic women, in both the general and 'high-risk' populations. Over the last decade screening strategies using the serum marker CA126 and transvaginal ultrasound have been refined and encouraging data have emerged on the impact of screening on ovarian cancer survival rates. Two randomized controlled trials are now underway in the general population to establish the impact of screening on ovarian cancer mortality while comprehensively tackling the issues of compliance, health economics and physical and psychological morbidity. In addition, trials in the high-risk population aimed at optimizing the current strategy have commenced in both the USA and the UK.

The performance of screening tests for ovarian cancer: results of a systematic review

OBJECTIVE

To estimate the performance of currently available tests in detecting ovarian cancer in asymptomatic women.

METHODS

Systematic review of prospective screening studies.

RESULTS

Twenty-five studies were identified: sixteen studied women at average risk and nine studied women at higher risk. Most studies evaluated only one screening method, were small, detecting few cancers, and gave few follow up details. Sensitivity estimates are therefore imprecise. In a typical larger study, reported sensitivity of ultrasound screening at one year was around 100% (95% CI 54%-100%), while the sensitivity of CA125 measurement followed by ultrasound (multimodal screening) was about 80% (95% CI 49%-95%). False positive rates ranged between 1.2% and 2.5% for grey scale ultrasound, between 0.3% and 0.7% for ultrasound with colour Doppler and between 0.1% and 0.6% for multimodal screening. This implies that, in annual screening of a population with an incidence of 40 per 100,000, and if no cancers were missed, between 2.5 and 60 women would undergo surgery for every primary ovarian cancer detected.

CONCLUSIONS

Ultrasound and multimodal screening can detect ovarian cancer in asymptomatic women, but there is currently no evidence on whether screening improves outcome for women in any risk group. On-going randomised controlled trials should establish the magnitude of any benefit of screening. The low prevalence of ovarian cancer in the population, and its rate of progression, may limit the potential cost-effectiveness of screening.

CA 125 as a screening test for ovarian cancer

BACKGROUND - Screening for ovarian cancer is based on ultrasound, colour Doppler, and tumour markers. There is only limited evidence on their discriminatory performance and no evidence on their effectiveness in reducing mortality. OBJECTIVE - To investigate the discriminatory performance of CA 125 as a screening test for ovarian cancer. METHODS - A registry of 15 093 serum samples drawn in 1968-72 was linked to the cancer registry. During follow up between 1968 and 1980 24 ovarian cancers were identified. One or two matched case-control design nested within the sample bank was applied and the concentrations of CA 125 were assessed. RESULTS - Case-control differences (relative risk 4-0, 95% confidence interval 1.0 to 15.5 at 20 kU/1) were found. Detection rate of the CA 125 test was 21-33% and the true negative rate was 75-98% depending on the cut off level and interval between drawing of the blood sample and diagnosis of the cancer. CONCLUSION - CA 125 is not a valid screening test if used alone. Case-control differences of borderline significance were found in CA 125 before diagnosis of ovarian cancer, but they were not large enough to provide a sufficient detection rate.