Clinical pearls:
- Primary HPV testing provides better protection against cervical cancer than cytology screening tests.
- HPV negative women who are at-least 40 years of age have a very low risk of cervical pathology and the screening interval can be increased to 10 years in Netherlands. All other women continued to be screened every 5 years.
- HPV positive women, who are triage negative, or negative for HPV 16/18 genotyping have a very high risk of developing CIN3+ or cervical cancer, and the screening intervals cannot be extended beyond 5 years.
- The use of HPV testing and age of the patient is the first step towards risk based screening.
Randomized
control trials in the past have shown that HPV based screening provides a
better protection against CIN3 than only cytology based screening. Dutch researchers have reported the results of
large population based study that confirms the findings from earlier studies.
They suggest that cervical cancer screening interval for those women who test
negative for HPV and are older (40+ years) can be safely extended from 5 to 10
years. All other women can get the screening at 5 years’ interval.
Separate
screening intervals are defined for women who are HPV negative and those who
were initially HPV positive but subsequent HPV negative after the triage test,
because they face different risks for CIN3.[1]
Many
countries (Australia, Italy, Netherlands, New Zealand, Sweden, and the UK)
around the world have adopted or recommended HPV screening as the primary
screening procedure and US still combines it with cytology. When advocating for change in policies, the
risk of interval cancer should also be taken into account. So longitudinal
studies are required to document the incidence of long term cervical cancer.
New data analysis
from the Netherlands was published in British Medical Journal, published 04
October 2016, suggest that the interval for cervical screening for HPV-negative
individuals, older than 40 years) could be extended from 5 years to 10 years;
all other women should continue to be screened every 5 years.[2]
The study is
a population based 14 years follow up of cohorts from earlier POBASCAM
randomized trial. (population based screening study Amsterdam). The follow up
of 14 years comprised of three screening rounds first at baseline, then at five
years and 10 years.
A total of 44 938
women aged between 29 and 61 were enrolled, 22 420 were randomized to the
intervention group (cytology and HPV co-testing) and 22 518 to the control
group (cytology with blinded HPV testing).
Follow up data
was collected till year 2013, till that point of time every woman had the
opportunity to undergo three rounds of 5-year screening.
Study
results showed that the cumulative incidence of cervical cancer and CIN3+ among
HPV negative women in the intervention group was similar to negative cytology
in control group after two rounds of screening.
Cervical
cancer and CIN risk ratios were .97 and .82 respectively.
In women
with HPV negative and in the age range of 40+ years, the CIN3+ incidence was
72% lower as compared to younger women.
(P <
.001).
Women who
were HPV-positive but had negative
results on HPV 16/18 genotyping and negative results on baseline and repeat
cytology testing had 10.4 times the cumulative risk of developing CIN3 than HPV-negative
women.
Similarly, HPV-positive
women with negative cytology triage had 11.9-fold higher risk for developing
cervical cancer than among HPV-negative women. After adding HPV 16/18
genotyping or repeat cytology as a triage test, only one cancer case was
observed.
The study results
show that HPV based screening programme provides a better protection as
compared to cytology results. Long term incidences of cervical cancer and CIN3+
were low among HPV negative women in this study cohort, and supports an
extension of the cervical screening interval beyond five years for women aged
40 years and older.
HPV positive
women with negative repeat cytology, HPV16/18
genotyping, and/or repeat cytology have at least a fivefold higher risk of
CIN3+ than HPV negative women, indicating that HPV based screening programmes
with long intervals (>five years) should be implemented with risk
stratification according to the age of the patients.
[1]
Bulkmans NWJ, Berkhof J, Rozendaal L, et al.
Human papillomavirus DNA testing for the detection of cervical intraepithelial
neoplasia grade 3 and cancer: 5-year follow-up of a randomised controlled
implementation trial. Lancet2007;370:1764-72.doi:10.1016/S0140-6736(07)61450-0 pmid:17919718.
[2]
http://www.bmj.com/content/355/bmj.i4924
No comments:
Post a Comment