Roxanne Nelson, RN, BSN
February 18, 2020
A unique study from New Mexico, which took into account all information from the entire state, regardless of the women's insurance provider, insurance coverage, healthcare provider, and location, shows that screening every 3 years dramatically reduces the rate of cervical cancer.
It also shows that 3 years is a safe interval, inasmuch as more frequent screening does not improve detection rates. Yet many women are being screened more frequently, which wastes healthcare resources, say the researchers.
The study was published in the International Journal of Cancer.
"A central value of our paper is that it does show safety for screening at 3-year intervals, which are recommended for the Pap smear alone," said lead author Cosette Wheeler, PhD, Regent's Professor of pathology, obstetrics, and gynecology at the University of New Mexico School of Medicine, Albuquerque.
"We found there is no additional benefit from screening more frequently, as there is excellent prevention of early-stage cervical cancers and over 80% of later-stage nonlocalized stage cervical cancers," she said.
Wheeler said that over the years, different guideline recommendations on cervical cancer screening have been issued by various US societies and organizations and that national guidelines issued in 2012 and updates from 2015 do not recommend screening more than every 3 years, regardless of age, for women who are not under surveillance for prior abnormalities.
"But through 2018, the New Mexico HPV Pap Registry shows that about half of all women are still being screened annually and biennially, which demonstrates a waste of healthcare dollars," she told Medscape Medical News.
"Potentially millions of dollars could be saved for New Mexico and beyond in the rest of the United States if we were actually screening every 3 years," she added.
"Importantly, this observation may reflect that clinicians and patients are not certain that 3-year intervals are safe," she added. "Following these guidelines changes a process that worked for many decades and is what both clinicians and patients are used to, but our data reassure everyone that 3-year screening intervals are appropriate."
At the same time, a growing number of women appear to be falling behind in their screening. "There are more women who are not screening after more than 5 years, and that proportion is increasing over time," said Wheeler. "Women who are getting only Pap tests have the largest increase in not coming back."
Intervals between screenings are also increasing among women who undergo co-testing, albeit not as dramatically.
"This supports a likelihood that without call recall systems, the US may have difficulty making sure that women don't fall beyond a period of a documented safe screening interval," she added.
Comprehensive Data Source
New Mexico is the only US state that has a complete record for cervical screening, diagnosis, and treatment. The New Mexico Tumor Registry (NMTR) records all cases of cancer and cancer-specific mortality, and the HPV Pap Registry records all cervical cancer screening results.
"Key to our study is the unique ability in New Mexico to link our two population-based registries to determine this on a state-wide basis," Wheeler told Medscape Medical News.
The study also veers from previous research in that it is "more representative of the vast array of healthcare delivery settings which provides care to Americans," she said. "It is not restricted to a limited location where women get screened, to a specific integrated or clinical setting, to a group or type of providers of care, or a group of patients within a system, and it represents women with heterogeneous risk for cervical cancer."
The registry also provides direct data to inform where and what interventions were needed. "It tells us where women are not being screened by geography, where women are being overscreened or underscreened, and where we need more than brick-and-mortar facilities to address lack of specialty care for women with positive screening results," Wheeler explained.
For the study, wheeler and colleagues collected data on all cervical cancer diagnoses in the NMTR during 2006–2016. The NMTR records were then linked with the New Mexico HPV Pap Registry (NMHPVPR), which provided information on each case regarding history of cervical screening and diagnostic and treatment results. The cervical cancer patients were then compared with control persons who were selected from the NMHPVPR.
A total of 876 women were diagnosed with cervical cancer during the study period. Of that group, records were available for 646 women who underwent screening during a period of 3 or more years. Almost half (47.9%) were diagnosed at age 35–54 years, 2.3% before age 25 years, and 15.8% at 65 years or older.
The stage at diagnosis was strongly related to the woman's age when she was diagnosed; 75.0% of women with stage I disease were younger than 35 years; 41.1% were aged 65 years or older. Similarly, only 5.3% of women aged 25–34 were diagnosed with stage IV disease, compared to 18.9% aged 65 or older.
Screening within a 3-year period was associated with a lower risk for each cancer stage as compared to screening during the past 5 years. For example, 22.5% of women with stage III+ cancer had been screened in the 3 years prior to being diagnosed, vs 59.3% of women with stage IA cancer.
These results also showed that being screened at more frequent intervals was not associated with better outcomes. Frequent screening, which was defined as being screened at least twice during a minimum period of 10 months, with no interval >30 months between screenings, was associated with a 90% reduction in the odds of nonlocalized cervical cancer and a 57% reduction in the odds of stage I disease in comparison with not undergoing screening for 5 years.
The study was funded by the US National Cancer Institute through several subcontracts with universities. Wheeler has received funds from grants, cooperative agreements, or subcontracts related to cervical screening and triage through her institution; several coauthors have reported relationships with industry.