Ovarian cancer screens not beneficial to women

In new guidance, the U.S. Preventive Services Task Force recommends against screening for ovarian cancer in women.1 The recommendation applies to asymptomatic women. Women with known genetic mutations that increase their risk for ovarian cancer, such as BRCA mutations, are not included in the guidance.

The task force's recommendation falls in line with screening guidelines by other medical and public health organizations. The American Cancer Society and the American College of Obstetricians and Gynecologists don't recommend screening asymptomatic, average-risk women for ovarian cancer.

The studies simply do not support any benefit in testing such women, and there is clear harm, such as unnecessary major surgery, says Virginia Moyer, MD, MPH, professor of pediatrics at Baylor College of Medicine in Houston and chair of the task force. Despite no data to indicate screening benefit, some doctors continue to recommend screening. A 2012 report, based on a survey of 1,088 doctors, indicated about one-third of those surveyed believed the screening was effective and that many routinely offered it to patients.2

"It is important that people follow this [guidance]," says Moyer. "This is expending resources to do a test which is almost certain to cause more harm than good, and is a very poor way to practice medicine."

No benefits confirmed

Women are rightly concerned about ovarian cancer. It has the highest mortality rate of all types of gynecologic cancer and is the fifth-leading cause of cancer death among women. In 2012, the American Cancer Society estimates about 22,280 new diagnoses and about 15,500 deaths from the disease.3 Most women with ovarian cancer are diagnosed in advanced stages of the disease and have a five-year survival rate of about 44%.4

The hope that early detection might improve prognosis prompted the National Cancer Institute's Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial. The trial enrolled nearly 80,000 women, ages 55-74, between November 1993 and July 2001 at 10 screening centers across the United States. The study was designed to evaluate the efficacy of the common screening routines of transvaginal ultrasound and testing with CA-125, a blood test used to measure the level of a tumor marker produced in higher amounts in women with ovarian or other cancers.

Half the women were screened annually with CA-125 for six years and transvaginal ultrasound for four years, and the other half had routine medical care without a screening. Both study groups were followed for a maximum 13 years until February 2010. The researchers then examined the ovarian cancer-specific mortality results from the two groups.

The data revealed that the difference in survival between the two groups was not statistically significant, suggesting simultaneous CA-125 and transvaginal ultrasound does not reduce disease specific mortality in women at average risk for ovarian cancer.5

The screenings were associated with bleeding, fainting, nausea, and bruising, investigators report. False positives often resulted in unnecessary diagnostic tests that were associated with infection, heart problems, and bowel injury. Of the women who received false-positive results, more than 1,080 had their ovaries removed; of those, more than 222 experienced a major surgical complication.5

More insight needed

Edward Partridge, MD, a gynecologic oncologist and director of the University of Alabama at Birmingham Comprehensive Center and a coauthor of the study, says, "This study shows that we need better markers that are more sensitive and specific for the disease, along with improved imaging technologies. We have scientists who are working in those areas, but more research and research funding is needed to help us better understand the beginnings of the disease, how it progresses, and how we can prevent it."

Science's real dilemma with ovarian cancer is that researchers are unsure if ovarian cancer truly starts out at stage 1, progressing through stages 2, 3, and 4, says Partridge. He suggests there is a "distinct" possibility that there are two types of ovarian cancer: one that starts out as Stage 1 and remains so for a long time, and another that might start out as stage 3, with a field effect. With such an effect, the mechanism for the development of the cancer on the surface of the ovary — its epithelial lining — also simultaneously affects the peritoneal cavity, says Partridge. If this premise is proven to be true, early detection will never make a difference — only an effective treatment, he states.

Even if testing could be improved to reduce false-positive results, it still would not save women's lives, says Partridge. The death rate would be the same whether women were screened or not, which suggests that the test simply cannot find the cancer early enough to make a difference.

"We need a lot of research," says Partridge. "Taking the current test and making it a little more sensitive, it is clear that it is not going to make any difference."

References

  1. Moyer VA; on behalf of the U.S. Preventive Services Task Force. Screening for ovarian cancer: U.S. Preventive Services Task Force reaffirmation recommendation statement. Ann Intern Med 2012. Doi:10.7326/0003-4819-157-11-201212040-00539.
  2. Baldwin LM, Trivers KF, Matthews B, et al. Vignette-based study of ovarian cancer screening: Do U.S. physicians report adhering to evidence-based recommendations? Ann Intern Med 2012;156(3):182-194.
  3. American Cancer Society. What are the key statistics about ovarian cancer? Accessed at http://bit.ly/rqRNuR.
  4. National Cancer Institute. SEER stat fact sheet. Ovary. Accessed at http://1.usa.gov/Sss0x.
  5. Buys SS, Partridge E, Black A, et al; PLCO Project Team. Effect of screening on ovarian cancer mortality: the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Randomized Controlled Trial. JAMA 2011; 305(22):2,295-2,303.