Anal warts increase the risk of developing precancerous lesions and cancer, especially in people with HIV


A new analysis published in AIDS and conducted by Dr Andreia Albuquerque at the University of Porto, Portugal, shows that having a history of anal warts increases the risk of developing precancerous lesions and anal cancer, especially in people living with it. HIV.

Currently, there are few standards to guide doctors on the frequency and extent of follow-up appointments when people develop anal warts. People living with HIV have a higher risk of developing anal cancer, and these results indicate that a history of anal warts may warrant additional monitoring to detect precancerous and cancerous lesions.


Human papillomaThe virus (HPV) is a group of more than 200 viruses that cause warts, of which around 40 are transmitted during anal, vaginal and oral sex. Although most people never get genital warts, almost everyone who hasn’t been vaccinated gets HPV in the first few years after having sex.

HPV also causes over 90% of all anal cancers, but little data specifically links anal warts to anal cancers. Popular wisdom has it that genital warts are generally associated with low-risk types of HPV that usually don’t cause cancer, while 14 strains of “high-risk HPV” cause cancer but don’t usually form warts. HPV is also responsible for most cases of cervical cancer.


squamous intraepithelial lesion (SIL)

This term is used to describe the detection of abnormal cells that have been “transformed” by HPV into a potentially precancerous condition. Depending on the degree of cell change, this will be referred to as low grade or high grade SIL (LSIL or HSIL). If SIL is detected, a colposcopy will usually be ordered.

human papillomavirus (HPV)

Some strains of this virus cause warts, including genital and anal warts. Other strains are responsible for cancer of the cervix, anal cancer and some cancers of the penis, vagina, vulva, urethra, tongue and tonsils.


Small scratches, sores or tears in the tissues. Lesions in the vagina or rectum can be cellular entry points for HIV.


When statistical data from all studies that relate to a particular research question and meet predetermined selection criteria are pooled and analyzed together.


Have a weakened immune system, therefore a reduced ability to fight infections and other diseases.

The type of lesions discussed in this review – called intraepithelial lesions – form in the layers of anal squamous cells. Squamous cells are flat cells found on the surface of the skin, in some organ mucous membranes, the lining of the respiratory tract, and the lining of the digestive tract, including in the anus. Low-grade squamous intraepithelial lesions can resolve on their own, but high-grade squamous intraepithelial lesions (HSIL), which are more common in men and women living with HIV, are usually treated as precancerous.

When anal squamous cells grow into tumors that grow deeper in tissue, it’s called anal squamous cell carcinoma (SCC), which encompasses 90% of all anal cancers.

The study

The current research is a meta-analysis performed on data contained in 18 previously published observational studies that took place between 1990 and 2020. The main objective of the study was to assess the prevalence of high-risk forms of HPV, HSIL, and SCC in people with a history of anal warts.

Many of the 18 studies involved men – most of whom were gay and bisexual – but a few included cisgender women. The studies took place mainly in Europe and the United States, but two took place in Asia (Japan and Taiwan) and two in South America (Brazil and Argentina). The meta-analysis only included studies for which physical samples or biopsies were taken from warts and lesions.

As part of their analysis, the authors compared “immunocompromised” people to “non-immunocompromised” people. In 17 of the 18 studies reviewed, the term ‘immunocompromised’ referred to people living with HIV with any number of CD4 cells, while a small study included people living with HIV and people undergoing pharmacologic immunosuppression. as a result of organ transplants or other medical conditions.

Despite the general understanding that anal warts are generally not associated with high-risk forms of HPV, this analysis found that of 525 people with a history of anal warts, 28.6% (95% confidence interval 19.0 – 40.6) had a form of HPV. This figure rose to 40.2% (21.0 1 – 63.1) of people living with HIV who had anal warts compared to 16.4% (10.7 – 24.3) of people HIV negative who have had warts.

The overall prevalence of high-grade squamous intraepithelial lesions (HSIL) in 1733 people with a history of anal warts was 13.8% (9.0 – 20.6). Almost a quarter of people living with HIV with a history of warts have developed HSIL (24.0%, 16.4 – 33.7).

On the positive side, the prevalence of anal squamous cell carcinoma (SCC) – the most common anal cancer – in 1,733 people with a history of warts was relatively low at 0.3% (0.0 – 1.7). Although this analysis shows that the absolute prevalence was still low for people living with HIV who had a history of warts (0.7%, 0.1 – 4.1), they were more than three times more likely to develop a CSC than other people.

Clinical screening

Since people with a history of anal warts (especially those living with HIV) had a higher risk of developing HSIL and SCC in this analysis, these results could affect clinical screening recommendations.

In 2019, Andreia Albuquerque, the first author of this meta-analysis, conducted a review of published guidelines and found that no country had adopted national standards for screening for HSIL or anal cancer. However, several health organizations specializing in STIs or colorectal diseases have published recommendations.

In these guidelines, regular anal Pap tests or anoscopy exams (both of which are used to identify lesions and abnormal squamous cells) are generally recommended for people with HIV, but the suggested frequency varies among organizations. Recommendations also vary as to whether and what other medical reasons (e.g. frequencies.

One reason for the lack of generalized and consistent guidelines is the lack of clinical trial data showing that screening reduces anal cancers in people living with HIV. The good news is that more data will soon be available from the ANCHOR trial, which looked at whether screening and treatment for HSIL in people living with HIV helps prevent anal cancer.

The references

Albuquerque A et al. High risk human papillomavirus, precancerous lesions and anal wart cancer. AIDS 35: 1939-1948. 2021.

DOI: 10.1097 / QAD.0000000000002975


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