What other recent developments in the diagnosis of ovarian cancer should clinicians be aware of?
Liquid biopsies using circulating tumor DNA (ctDNA) have shown promising results for cancer detection and management, including ovarian cancer. However, further clarification is needed to define the minimum tumor size/burden detectable using ctDNA-based approaches. Moreover, large prospective studies are needed to determine the clinical utility of ctDNA detection for early diagnosis of ovarian cancer and its impact on patient outcomes.
DNA methylation is an early event in carcinogenesis and can be detected in blood plasma samples from cancer patients. Data related to the discovery and validation of discriminated methylated DNA marker candidates extracted from ovarian cancer tissues were presented at the American Society of Clinical Oncology meeting this year. Findings were subsequently evaluated in plasma from women with and without ovarian cancer.
In addition to blood, peritoneal fluid and uterine lavage have been used to obtain cell pellets that are used for the identification of common mutant genes – TP53, BRCA1, and BRCA2. These body fluids have also been shown as the source of tumor-derived material that can be used to differentiate between ovarian cancer patients and healthy individuals.
Further studies are needed to determine the sensitivity and specificity of other noninvasive tests for the diagnosis of ovarian cancer.
The American Cancer Society issued a statement that the human papillomavirus (HPV) test is the preferred cervical cancer screening tool. Why do they prefer the HPV test over the Pap test?
The American Cancer Society recommends that cervical cancer testing (screening) begin at age 25 years. Women aged 25-65 years should have a primary HPV test every 5 years. If primary HPV testing is not available, screening may be done with either a co-test that combines an HPV test with a Pap test every 5 years or a Pap test alone every 3 years.
The HPV test is widely available. The cost of an HPV test is approximately $44 (unit cost, 2014 USD). The cost of a Pap test is approximately $30 (unit cost, 2014 USD).
The HPV test is preferred over cytologic testing (Pap) for several reasons.
Firstly, in well-designed studies, the sensitivity of a single Pap smear for detecting high-grade precancer of the cervix is around 50%, which is less than optimal for a cancer screening test. Sensitivity means the chance that, if you have the disease (in this case, high-grade precancer of the cervix), the test will detect it. In particular, cytology is known to have an even more limited ability to detect glandular precancers, which arise in the endocervical canal rather than on or in close proximity to the exterior surface of the cervix (ectocervix). Thus, HPV-based screening programs hold the promise of improving detection of cervical adenocarcinoma.
Secondly, to function reliably, cytology programs require substantial infrastructure, highly qualified human resources, and a well‐defined quality-control system, which have proved to be costly and difficult to implement. This results in global disparities in cytology-based cervical cancer screening programs.
Thirdly, although co‐testing with both cytology and HPV tests is an option for screening programs, studies have confirmed that there is limited benefit from adding cytology to HPV screening. Long‐term studies from Kaiser Permanente that included over 1 million women found that HPV testing has a very high negative predictive value for precancerous lesions. Women with negative HPV tests were very unlikely to develop precancerous lesions in the following 5 years. The 5‐year risk of high-grade precancer or cancer of the cervix following a negative HPV test was 0.14%, whereas for women with a negative cytology, it was 0.31%. The screening benefit of co‐testing is largely driven by HPV testing and not cytology.
So, in summary, HPV testing is preferred over cytologic screening for cervical cancer, given its improved sensitivity and quality assurance, the opportunity to automate testing, and ultimately, its prospect of reducing the overall number of lifetime screenings for women.
Dr. Stone has disclosed no relevant financial relationships.
A version of this article originally appeared on Medscape.com.