Anal Cancer Screening Guidelines for PLHIV
Last updated: November 2024
Appendix 1. Grading of recommendations
ASHM recommendations are rated according to the criteria used by the US National Institutes of Health Panel on Guidelines for the Prevention and Treatment of Opportunistic Infections in Adults and Adolescents With HIV. The letters A, B, or C signify the strength of the recommendation for or against a preventive or therapeutic measure, and the Roman numerals I, II, or III indicate the quality of the evidence supporting the recommendation. In cases where there are no data for the prevention or treatment of an Opportunistic Infection based on studies conducted in people with HIV, but there are data derived from studies in people without HIV that could plausibly guide management of patients with HIV, the recommendation is rated II or III but is assigned A, B, or C depending on the strength of the recommendation.
Table. Rating System for Prevention and Treatment Recommendations18
| Strength of Recommendation | Quality of Evidence for the Recommendation |
|---|---|
| A: Strong recommendation for the statement. | I: One or more randomized trials with clinical outcomes and/or validated laboratory endpoints. |
| B: Moderate recommendation for the statement. | II: One or more well-designed, non-randomized trials or observational cohort studies with long-term clinical outcomes. |
| C: Weak recommendation for the statement. | III: Expert opinion. |
Appendix 2. Details of sampling and reporting
Before commencing anal screening, it is advisable to contact your pathologist to obtain advice on appropriate sampling devices and collection media, as samplers and collection fluids are not always interchangeable. It is also important to ascertain whether the laboratory offers NATA-accredited HPV genotyping. At the time of writing, specific Medicare rebates for anal HPV and cytology testing are not available.
The anal canal should be sampled with an appropriate collection device, usually a Dacron or flocked swab. The aim is to obtain an appropriately cellular sample, which is representative of the circumference and length of the canal (UCSF resource: Obtaining a specimen for anal cytology | Anal Neoplasia Clinic, Research and Education Center). There is no clear relationship between recent sexual activity and cellularity1 but by convention, most individuals are advised against douching and receptive intercourse for 24 hours prior to the procedure. Lubricant should not be used before or during sampling, as this can interfere with test preparation and interpretation. Sampling of the canal should occur without direct visualisation as the presence of the anoscope interferes with access to the mucosal surface2.
The anal swab must be collected prior to digital ano-rectal examination.
Self-collection may be more acceptable to those being screened, but a recent meta-analysis showed a small drop in performance compared to clinician-collected samples3. In the current guidelines, self-sampling is not recommended but this is an area of further research.
As the swab sample will be used for both anal HPV and cytology testing, it must be submitted in a vial of appropriate fixation solution, provided by the manufacturer of the particular liquid-based cytology (LBC) technique (eg ThinPrep or SurePath) or by the pathology laboratory. After collection, the swab should immediately be very vigorously rinsed in the fixative, to maximise cellularity of the specimen. The head of the device should not be detached to leave in the vial. After rinsing, the swab may be safely discarded in clinical waste.
An appropriate request form should accompany the specimen to the laboratory. At a minimum, this should indicate that the test requested is ‘anal cancer screening as per ASHM guidelines’, as this will communicate the HIV status and the need for extended HPV genotyping +/- reflex LBC.
Detection of at least 14 high-risk HPV genotypes is standard in Australia laboratories processing cervical specimens. The cervical testing usually includes only partial genotyping, individually identifying only HPV16 and HPV 18, while the other 12 genotypes are detected and reported as a panel of ‘other high-risk’ types. Extended HPV genotyping is recommended for anal testing as this will help to enable differentiation of transient and persistent infections. The 14 genotypes individually detected are:16,18,31,33,35,39,45,51,52,56,58,66,68.
A small proportion of samples may be reported as ‘unsatisfactory’ or ‘invalid’ for PCR and genotyping. This may be due to absence of DNA (insufficient cells) or the PCR reaction may be ‘inhibited’ if a competitive substance is present, thereby rendering the PCR unreliable. When encountered, these results may necessitate recollection.
LBC methods are far preferable to the conventional “smear” technique and are recommended by these guidelines. The resultant slide should be manually screened by a suitably trained cytologist. A similarly suitably experienced cytopathologist should take responsibility for a final report, utilising the Australian Modified Bethesda System, which is already used in Australia for cervical cytology reporting (See Table). This is easily translatable to the Bethesda System 2014, if required4. If the slide is not assessable, the term ‘Unsatisfactory’ will be used. The main reason for such a report is poor cellularity and the collection should be repeated within 2-4 weeks. Discussion with the reporting pathologist before recollection may be helpful, to clarify and rectify the problem. A comment will also be made about the presence or absence of transformation zone cells, an important quality measure5.
| Table: Australian Modified Bethesda System for reporting anal cytology | |
|---|---|
| Negative | There is no evidence of a squamous intraepithelial lesion or malignancy |
| PLSIL | Possible low-grade squamous intraepithelial lesion |
| LSIL | Low-grade squamous intraepithelial lesion |
| PHSIL | Possible high-grade squamous intraepithelial lesion |
| HSIL | High-grade squamous intraepithelial lesion |
| SCC | Squamous cell carcinoma |
| Unsatisfactory | Insufficient cellular material |
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