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What Is the Risk of Anal Carcinoma in Patients With Anal Intraepithelial Neoplasia III?

Lee, Grace C., M.D.; Kunitake, Hiroko, M.D., M.P.H.; Milch, Holly, N.P.-C.; Savitt, Lieba R., N.P.-C., R.N.-C., M.S.N.; Stafford, Caitlin E., B.S.; Bordeianou, Liliana G., M.D., M.P.H.; Francone, Todd D., M.D., M.P.H.; Ricciardi, Rocco, M.D., M.P.H.

doi: 10.1097/DCR.0000000000001219
Original Contributions: Colorectal Cancer
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BACKGROUND: The risk of anal carcinoma after previous diagnosis of anal intraepithelial neoplasia III is unclear.

OBJECTIVE: The purpose of this study was to estimate the risk of anal carcinoma in patients with anal intraepithelial neoplasia III and to identify predictors for subsequent malignancy.

DESIGN: This was a retrospective review using the Surveillance, Epidemiology, and End Results registry (1973–2014).

SETTING: The study was composed of population-based cancer registries from the United States.

PATIENTS: Patients who were diagnosed with anal intraepithelial neoplasia III were included.

MAIN OUTCOME MEASURES: The primary outcome was rate of subsequent anal squamous cell carcinoma. Predictors for anal cancer were identified using logistic regression and Cox proportional hazard models.

RESULTS: A total of 2074 patients with anal intraepithelial neoplasia III were identified and followed for a median time of 4.0 years (interquartile range, 1.8–6.7 y). Of the cohort, 171 patients (8.2%) subsequently developed anal cancer. Median time from anal intraepithelial neoplasia III diagnosis to anal cancer diagnosis was 2.7 years (interquartile range, 1.1–4.5 y). Fifty-two patients (30.4%) who developed anal carcinoma were staged T2 or higher. Ablative therapies for initial anal intraepithelial neoplasia III were associated with a reduction in the risk of anal cancer (OR = 0.3 (95% CI, 0.1–0.7); p = 0.004). Time-to-event analysis revealed that the 5-year incidence of anal carcinoma after anal intraepithelial neoplasia III was 9.5% or ≈1.9% per year.

LIMITATIONS: The registry did not record HIV status, surveillance schedule, use of high-resolution anoscopy, or provider specialty.

CONCLUSIONS: In the largest published cohort of patients with anal intraepithelial neoplasia III, ≈10% of patients were projected to develop anal cancer within 5 years. Nearly one third of anal cancers were diagnosed at stage T2 or higher despite a previous diagnosis of anal intraepithelial neoplasia III. Ablative procedures were associated with a decreased risk of cancer. This study highlights the considerable rate of malignancy in patients with anal intraepithelial neoplasia III and the need for effective therapies and surveillance. See Video Abstract at http://links.lww.com/DCR/A764.

Section of Colon and Rectal Surgery, Division of General and Gastrointestinal Surgery, Department of Surgery, Massachusetts General Hospital, Boston, Massachusetts

Supplemental digital content is available for this article. Direct URL citations appear in the printed text, and links to the digital files are provided in the HTML and PDF versions of this article on the journal's Web site (www.dcrjournal.com).

Funding/Support: Dr Lee was supported by the National Institutes of Health T32 Research Training in Alimentary Tract Surgery grant DK007754-13.

Financial Disclosure: None reported.

Podium presentation at the meeting of The American Society of Colon and Rectal Surgeons, Nashville, TN, May 19 to 23, 2018.

Correspondence: Rocco Ricciardi, M.D., M.P.H., Section of Colon and Rectal Surgery, Massachusetts General Hospital, 15 Parkman St, WAC-4–460, Boston, MA 02114. E-mail: rricciardi1@mgh.harvard.edu

© 2018 The American Society of Colon and Rectal Surgeons