1. Overview of anal cancer in MSM living with HIV
Anal cancer is defined as a cancer arising either from the squamous or glandular epithelia of the anus. The vast majority are squamous cell carcinomas (SCC), with remainder cancers coded as adenocarcinomas, neuroendocrine neoplasm, malignant melanoma, mesenchymal tumours and lymphoma[1-4]. Anal cancers are distinguished anatomically as intracanal (arising from the anal canal which extends between the rectum to perianal skin) or perianal (arising from the skin within 5cm diameter from the anal verge).
Anal cancer is relatively rare in the general population with incidence rates between one to two per 100,000 person-years [1 3 5 6]. However, for MSM living with HIV, a recent meta-analysis estimated a pooled incidence rate of 77.8 per 100,000 person-years. This is comparable with other common cancers in the general Australian population.
Anal cancer has devastating effects on the patient when diagnosed. It has been estimated that the utility value of anal cancer to be 0.57 (where 0 equates to death and 1 equates to perfect health). Indeed, anal cancer and its treatment has been shown to affect quality of life, including a diminished social role, lowered ability to work and economic distress. Whilst early perianal cancers may be treated with local excision, anal cancers generally require combined chemoradiotherapy as mainstay treatment. The field of anal cancer treatment has evolved significantly with newer radiation technologies allowing more precise targeting of cancer and reducing normal tissue toxicities. Reports show excellent cancer outcomes with less severe grade 3/4 toxicities, especially when anal cancers have been detected at earlier stages[12 13].
2. Screening for anal cancer
Two models for anal cancer screening currently exist: 1) a secondary prevention model where the aim is to detect and treat the presumed precursor lesion (high-grade squamous intraepithelial neoplasia (HSIL) using anal pap smears and/or high resolution anoscopy, in order to prevent progression to anal cancer; 2) a tertiary prevention model where the aim is to detect early anal cancers, using regular perianal and digital ano-rectal examination (DARE) in order to optimise management.
In Australia, the majority of doctors managing HIV patients recognise the importance of screening for anal cancer but few are routinely screening currently. The availability of secondary prevention screening using anal pap smears is restricted to some major cities where high resolution anoscopists can follow up abnormal cytology. For the majority of Australian MSM living with HIV, this is not a practical option for them.
3. What should be done now?
In an audit of anal cancers in Victoria, the average size of anal cancer in people living with HIV was 2.9cm at diagnosis, and most were visible and/or palpable for some time before definitive diagnosis.
Therefore, improving the awareness for the increased risk of anal cancer is a priority for MSM living with HIV. If a man at risk for anal cancer can present earlier to their HIV doctor, there may be improved survival and morbidity from anal cancer treatment modalities if their cancer is diagnosed at an early stage.
Furthermore, there is now increasing evidence that incorporating regular digital ano-rectal examination (DARE) into routine HIV care for those at highest risk for anal cancer (i.e. MSM living with HIV) is acceptable to patients and clinicians, and cost-effective in an Australian context [19 20]. For more detailed evidence of the role of DARE in anal cancer screening, please see J Med Screening ACE Study. In settings where screening with anal cytology is not available, offering regular DARE to MSM living with HIV should be the minimum standard of care in order to detect anal cancers earlier.
4. Resources for increasing awareness of anal cancer with your patients
5. Resources for how to incorporate DARE into your routine HIV practice
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11 Glynne-Jones R, Northover JM, Cervantes A, et al. Anal cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of oncology : official journal of the European Society for Medical Oncology / ESMO 2010;21 Suppl 5:v87-92 doi: 10.1093/annonc/mdq171[published Online First: Epub Date]|.
12 Kachnic LA, Winter K, Myerson RJ, et al. RTOG 0529: a phase 2 evaluation of dose-painted intensity modulated radiation therapy in combination with 5-fluorouracil and mitomycin-C for the reduction of acute morbidity in carcinoma of the anal canal. Int J Radiat Oncol Biol Phys 2013;86(1):27-33 doi: 10.1016/j.ijrobp.2012.09.023[published Online First: Epub Date]|.
13 Yates A, Carroll S, Kneebone A, et al. Implementing Intensity-modulated Radiotherapy with Simultaneous Integrated Boost for Anal Cancer: 3 Year Outcomes at Two Sydney Institutions. Clinical oncology 2015 doi: 10.1016/j.clon.2015.08.006[published Online First: Epub Date]|.
14 Palefsky JM, Holly EA, Hogeboom CJ, et al. Anal cytology as a screening tool for anal squamous intraepithelial lesions. J Acquir Immune Defic Syndr Hum Retrovirol 1997;14(5):415-22
15 Read T, Vodstrcil L, Grulich A, et al. Acceptability of digital anal cancer screening examinations in HIV-positive homosexual men. HIV Med 2013;14(8):491-6 doi: 10.1111/hiv.12035[published Online First: Epub Date]|.
16 Ong JJ, Temple-Smith M, Chen M, et al. Why are we not screening for anal cancer routinely - HIV physicians inverted question mark perspectives on anal cancer and its screening in HIV-positive men who have sex with men: a qualitative study. BMC public health 2015;15(1):67 doi: 10.1186/s12889-015-1430-1[published Online First: Epub Date]|.
17 Read T, Huson K, Millar J, et al. Size of anal squamous cell carcinomas at diagnosis: a retrospective case series. Int J STD AIDS 2013;24(11):879-82 doi: 0956462413486776 [pii]10.1177/0956462413486776[published Online First: Epub Date]|.
18 Ong JJ, Chen M, Grulich A, et al. Exposing the gaps in awareness, knowledge and estimation of risk for anal cancer in men who have sex with men living with HIV: a cross-sectional survey in Australia. J Int AIDS Soc 2015;18(1):19895 doi: 10.7448/IAS.18.1.19895[published Online First: Epub Date]|.
19 Ong JJ, Fairley CK, Carroll S, et al. Cost-effectiveness of screening for anal cancer using regular digital ano-rectal examinations in men who have sex with men living with HIV. J Int AIDS Soc 2016;19(1):20514 doi: 10.7448/IAS.19.1.20514[published Online First: Epub Date]|.
20 Ong J, Grulich A, Walker S, et al. Baseline findings from the Anal Cancer Examination (ACE) study: screening using digital ano-rectal examination in HIV-positive men who have sex with men Journal of medical screening 2015;doi: 10.1177/0969141315604658