Updates in Pap Screening and Management, Part I
/Here’s the RoshReview Question of the Week:
A 26-year-old woman presents to the office to review her Pap smear results. Her Pap smear showed atypical squamous cells of undetermined significance with positive human papillomavirus testing. Her previous Pap results are unknown. What is the best next step in management, given this result?
We talked about Pap screening last in July 2019 and managing an abnormal Pap in January 2020.
Shortly after, the ASCCP published its updated screening and management guidelines!
And they updated their awesome Pap management app – if you have $10 to spare, you’ll definitely get value out of it in residency and likely beyond.
What’s new with Pap screening?
Short answer – not a lot, but there is controversy!
In July 2020, the American Cancer Society published new recommended screening guidelines for individuals at average risk, with three major changes:
Recommendation of primary HPV testing every 5 years as the screening strategy, rather than co-testing.
Beginning Pap screening at age 25, rather than age 21.
Co-testing and/or cytology are acceptable per old guidelines, but ultimately the guidelines are meant to be transitory until facility/area has accessible primary HPV testing.
The USPSTF guidelines overall remain unchanged (for now!), but do include the option for primary HPV testing. Highlights:
Screening with cytology alone starting at age 21, q3 years.
Co-testing acceptable at age 25, and can space with cotesting to q5 years, HPV primary screening q5 years, or cytology alone q3 years.
Ending screening after benign hysterectomy with no prior high risk dysplasia, or 25+ years after high-grade dysplasia, presuming adequate negative screening previously.
How does ASCCP feel?
They note that evidence does exist that primary HPV screening is safe and effective as a cancer screening strategy, and in increasingly-immunized populations appears to be more effective than cytology-based screening.
One referenced study noted 5-fold higher detection rates in patients with CIN2+ based on HPV screening versus cytology beginning at age 21.
However, uptake has been slow and implementation has been challenging, and thus they do endorse the USPSTF guidelines that suggest greater flexibility.
They offer a more qualified statement of support for the ACS guidelines in locations that can equitably and effectively implement primary HPV screening.
They also recognize that HPV self-collection may help increase access and availability to patients, and hope to identify more evidence of comparative efficacy to provider-collected specimens.
Comparison of USPSTF 2018 and ACS 2020 screening guidelines (ASCCP statement).
Managing Abnormal Pap Smears
In our last episode, we gave a framework that first separated Paps into “high grade” and “low grade,” age, and HPV status. We’ll apply that again and re-review the management.
Ultimately, the guidelines are framed around the question of what CIN3+ risk exists:
The first question: is the immediate risk greater than/equal to 4%?
If yes → how high is that risk?
If 60+%, then expedited treatment is preferred
If 4-24%, then colposcopy is preferred
If in between, either is acceptable.
If immediate risk of CIN3+ is less than 4%:
What is the risk of CIN3+ within 5 years?
If > 0.55%, then return in 1 year for screening.
If between 0.15 and 0.54%, then return in 3 years.
If < 0.15%, then return in 5 years.
“Equal management for equal risk” is the underlying principle.
ASCCP also adjusts risk given the clinical situation, such as a routine screen; a patient who is rarely screened; management of results during post-colposcopy surveillance; or follow ups after excision/treatment.
ASCCP
So let’s go through possible results on Pap smears at this point.
We’ll presume that you are either performing co-testing, or HPV-primary screening with reflex to cytology.
We’ll also presume that the patients we mention here are undergoing “routine screening” – meaning that they’ve had prior screening, or it is their first screen in their lifetime if they are under age 30.
Finally, given the additional nuances with screening, we strongly recommend reviewing management steps using the ASCCP app for guidance.
We will just review the first steps in management plans; follow ups get very much into the weeds and are individualized – a huge plus for patients, but much more challenging for memorization!
HPV Primary Screening Management
HPV 16/18+ – colposcopy (and obtain reflex cytology).
HPV other + – reflex cytology, then follow the appropriate cytology guidelines!
Cytology/Cotesting Guidelines
Normal Cytology.
The only potential abnormal in this category for someone 25 years or older is HPV positive. The risk of CIN 2 or greater in this population is approximately 2-6%. It increases if HPV is persistently positive over time, or is type 16/18.
If typed and result is HPV-16 or HPV-18, colposcopy is recommended.
If untyped or not 16/18, repeat cotesting in 1 year.
Low Grade Cytology (ASC-US, LSIL)
Age 21-24, ASC-US and LSIL get treated the same, with the recommendation for repeat cytology in 12 months.
This is because the clearance of HPV-caused ASC-US and LSIL is overall high in this group, and colposcopy may lead to overly aggressive management.
As long as there’s no progression to high-grade, there is no indication for colposcopy.
In patients aged 25-29 and 30-64, the management of LSIL and ASC-US are similar.
Age 30-64, ideally HPV testing is always available by cotesting or primary screening!
The USPSTF guidelines in 25-29 year olds though do call for cytology q3 years as the primary screening strategy.
LSIL or ASC-US, HPV negative: overall low risk of malignant transformation.
Thus, with LSIL, can repeat cotesting in 1 year.
With ASCUS, repeat in 3 years.
LSIL, HPV unknown: get colposcopy given unknown HPV status.
ASC-US, HPV unknown: repeat cytology in 3 years if 25-29, and 1 year if 30-64
Ideally both would have co-testing on the repeat evaluation!
LSIL or ASC-US, HPV positive: colposcopy should be performed.
The 5-year CIN3+ risk for both HPV+ ASCUS and LSIL are very similar, approximately 7%.
Finally in patients aged 65+, Pap smears are likely only continuing at this point if there have been previous abnormalities, or a lack of screening. Thus, ASC-US or LSIL with negative HPV should be treated as abnormal, and thus merit repeat cytology in 1 year. All other abnormalities (i.e., HPV positive) in this age group should receive colposcopy!
Note that we didn’t talk excisional procedures at all; low grade lesions (ASC-US, LSIL) should generally proceed to colposcopy before considering excision.
Part II will encompass high grade lesions, so stay tuned!