A meta‐analysis of anal cancer incidence by risk group: Toward a unified anal cancer risk scale

• Published in: International journal of cancer Vol. 148; no. 1; pp. 38 - 47
• Main Authors: Clifford, Gary M., Georges, Damien, Shiels, Meredith S., Engels, Eric A., Albuquerque, Andreia, Poynten, Isobel Mary, Pokomandy, Alexandra, Easson, Alexandra M., Stier, Elizabeth A.
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01-01-2021; Wiley Subscription Services, Inc
• Subjects: Adult; Age Factors; Anal cancer; Anus; Anus Neoplasms - epidemiology; Autoimmune diseases; Autoimmune Diseases - epidemiology; Cancer; Cancer Epidemiology; Cervix; Colorectal cancer; Crohn's disease; Female; Genital Neoplasms, Female - epidemiology; Genital Neoplasms, Female - pathology; Genital Neoplasms, Female - virology; HIV; HIV Infections - epidemiology; Human immunodeficiency virus; Human papillomavirus; Humans; Incidence; Male; Medical research; Meta-analysis; Middle Aged; MSM; Organ Transplantation - adverse effects; Organ Transplantation - statistics & numerical data; Papillomavirus Infections - epidemiology; Papillomavirus Infections - pathology; Papillomavirus Infections - virology; Precancerous Conditions - diagnosis; Precancerous Conditions - epidemiology; Precancerous Conditions - virology; Public health; Risk Assessment - statistics & numerical data; Risk Factors; Sex Factors; Sexual and Gender Minorities - statistics & numerical data; Standardization; Systemic lupus erythematosus; transplantation; Ulcerative colitis; Vagina; HIV; anal cancer; incidence; MSM; transplantation
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.33185

Certain population groups are known to have higher than average anal cancer risk, namely persons living with HIV (PLHIV), men who have sex with men (MSM), women diagnosed with human papillomavirus (HPV)‐related gynecological precancerous lesions or cancer, solid organ transplant recipients (SOTRs) and patients with autoimmune diseases. Our aim was to provide robust and comparable estimates of anal cancer burden across these groups. Summary incidence rates (IRs), as cases per 100 000 person‐years (py), were calculated by fixed‐effects meta‐analysis. IRs were 85 (95% confidence interval [CI] = 82‐89) for HIV‐positive MSM (n = 7 studies; 2 229 234 py), 32 (95% CI = 30‐35) for non‐MSM male PLHIV (n = 5; 1626 448 py) and 22 (95% CI = 19‐24) for female PLHIV (n = 6; 1 472 123 py), with strong variation by age (eg, from 16.8 < 30 years to 107.5 ≥ 60 years for HIV‐positive MSM). IR was 19 (95% CI = 10‐36) in HIV‐negative MSM (n = 2; 48 135 py). Anal cancer IRs were much higher after diagnosis of vulvar (IR = 48 [95% CI = 38‐61]; n = 4; 145 147 py) than cervical (9 [95% CI = 8‐12]; n = 4; 779 098 py) or vaginal (IR = 10 [95% CI = 3‐30]; n = 4; 32 671) cancer, with equivalent disparity after respective precancerous lesions. IR was 13 (95% CI = 12‐15) in SOTRs (n = 5; 1 946 206 py), reaching 24.5 and 49.6 for males and females >10 years after transplant. Anal cancer IRs were 10 (95% CI = 5‐19), 6 (95% CI = 3‐11) and 3 (95% CI = 2‐4) for systemic lupus erythematosus, ulcerative colitis and Crohn's disease, respectively. In conclusion, a unifying anal cancer risk scale, based upon comprehensive meta‐analysis, can improve prioritization and standardization in anal cancer prevention/research initiatives, which are in their public health infancy.
What's new?
Anal cancer (AC) is quite rare in the general population. However, some groups are known to be at higher risk. In this meta‐analysis, the authors identified these groups (e.g., HIV‐positive status, other HPV‐related cancers, etc.), and were then able to develop an AC‐risk scale based on incidence estimates. Because there is currently no consensus regarding standardized screening for AC, this risk scale can help clinicians to prioritize and compare risk profiles for AC research and prevention initiatives. These can then be guided by similar principles of management for populations with similar absolute risk.