To the Editor:

We appreciate the recent article on preventive care for men who have sex with men (MSM).¹ It sheds light on crucial aspects of health maintenance for this key demographic. However, the article could have delved deeper into two specific areas: doxycycline postexposure prophylaxis (doxy PEP) and the updated anal cancer screening guidelines of the International Anal Neoplasia Society.

Doxy PEP is an emerging intervention for the prevention of sexually transmitted infection (STI) and has the potential to significantly reduce the risk of gonorrhea, chlamydia, and syphilis, particularly among MSM and transgender women. The regimen consists of a single 200-mg dose of doxycycline taken up to 72 hours after unprotected sex. A trial of doxy PEP in the United States found a substantial decrease in the incidence of STIs among MSM and transgender women, with a remarkable 67% reduction in all STIs and an 88% reduction in chlamydia.² Additionally, the DOXYVAC trial and other studies further validate the effectiveness of doxy PEP, showing significant reductions in STI incidence among MSM receiving HIV preexposure prophylaxis.³ The US Centers for Disease Control and Prevention has published guidelines on appropriate use of doxy PEP for at-risk populations.⁴

Recent updates to the anal cancer screening guidelines of the International Anal Neoplasia Society add crucial insights into early detection and prevention strategies for anal cancer, especially for MSM and transgender women. The guidelines recommend initiating screening at 35 years of age in MSM and transgender women with HIV; other HIV-positive patients and MSM and transgender women without HIV should be screened beginning at 45 years of age. Screening can be performed via anal cytology with or without cotesting for high-risk human papillomavirus.⁵ The guidelines are supported by multiple large studies, most notably the 2022 Anal Cancer HSIL Outcomes Research trial, which conclusively showed that treatment of high-grade anal precursor lesions significantly decreases incident anal cancer events.⁶

Family physicians should discuss doxy PEP and anal cancer screening with eligible MSM to improve long-term health outcomes for these patients.

In Reply:

We thank the authors for their letter regarding doxy PEP and anal cancer screening guidelines as outlined by the International Anal Neoplasia Society. These topics are very important, and we agree with their conclusion that the family physician who cares for eligible MSM and transgender women in their practice should be aware of these resources.

We acknowledge that doxy PEP has shown a risk reduction for the common bacterial STIs of chlamydia, gonorrhea, and syphilis. We do acknowledge awareness at the time of drafting our article of this strategy, and the referenced studies demonstrate reduced incidence of the target STIs when using doxycycline appropriately as PEP.^1,2 As of June 6, 2024, there are published guidelines on the use of doxy PEP by Bachmann, et al.³ These guidelines clearly outline patients who would most benefit from doxy PEP and the implementation strategies. We agree that doxy PEP appears to be a relatively safe and effective strategy that the family physician can discuss with their patient when appropriate.

We used the International Anal Neoplasia Society guideline reference from 2019 for our recommendations in the article.⁴ We acknowledge the new guidelines published in May 2024,⁵

although the new guidelines would not change the age recommended for screening MSM with HIV (35) and would lower the age for screening MSM without HIV from 50 to 45. The recommended screening strategy for MSM without HIV should include the digital anal rectal examination and anal cytology with consideration for high risk human papillomavirus testing.⁵

We appreciate this updated information and agree that the family physician caring for MSM and transgender women should be knowledgeable and able to discuss doxy PEP and current screening guidelines with their patients.