Abstract
The incidence of squamous cell carcinoma of the anus, anal canal, and anorectum (SCCA) has increased over time. However, there are still no national guidelines on screening for SCCA among high-risk populations. Providers at University of California, San Francisco have been at the forefront of providing anal dysplasia screening. To determine whether such a screening program allows for earlier detection of abnormalities and consequently, improves patient survival, we conducted an ecological study using data from the Surveillance, Epidemiology, and End Results (SEER) program to compare the San Francisco-Oakland catchment area (SF-O) to other SEER sites where routine screening has not been as accessible. Cox regression models were utilized to assess the impact of residing in the SF-O region, versus other SEER sites, on cause-specific mortality hazard. Logistic regression was used to determine if site was associated with the probability of having an in situ versus invasive tumor among SCCA cases. All analyses were stratified on calendar time (1985–1995 and 1996–2008) to compare differences pre- and post- highly active anti-retroviral therapy. Among SCCA cases, being reported by the SF-O registry was associated with a four fold higher probability of having an in situ tumor (rather than an invasive tumor) [95% CI: 3.48–4.61], compared to sites outside of California, between 1996 and 2008. Cases reported from the SF-O region between 1996 and 2008 had a 39% lower mortality risk than those reported from registries outside California (95% CI: 0.51–0.72). However, there was no decrease in the rate of invasive SCCA over this period. This is the first ecological study to evaluate whether access to anal cancer screening programs may help improve patient survival by allowing for earlier detection of lesions. Our results imply that routine screening programs may help detect SCCA at an earlier stage and thus, potentially impact patient survival.
Highlights
Rare in the U.S, squamous cell carcinoma of the anal canal comprises approximately 2% of all intestinal cancers globally [1,2]
21.02 (16.83–26.26) 5.35 (4.36–6.56) ref with an increased mortality risk in both pre- and post-HAART models. To our knowledge this is the first ecological study to explore whether access to anal cancer screening programs may help improve patient survival by allowing for earlier detection and treatment of pre-malignant anal lesions
We compared the incidence and outcomes of SCCA from other SEER registries in the U.S to the San Francisco-Oakland catchment area (SF-O) SEER registry, because unlike other SEER-associated geographic areas, SF-O has several anal dysplasia clinics [20], including the anal dysplasia clinic at UCSF, one of the most established anal dysplasia clinics in the U.S Our results indicated that a large proportion of cases reported from the SF-O region had in situ SCCA at the time of diagnosis
Summary
Rare in the U.S, squamous cell carcinoma of the anal canal comprises approximately 2% of all intestinal cancers globally [1,2]. Risk factors include infection with human papillomavirus (HPV) and immunosuppression [3]. In the U.S and other developed countries, the incidence of squamous cell carcinoma of the anus, anal canal, and anorectum (SCCA) has continually increased over the last several decades [4,5,6,7]. The highest risk population is HIV-infected MSM, among whom the incidence has been estimated to be 30–100 times the general population [9,11,12,13]. Early-stage SCCA is readily treatable with chemotherapy and radiation, in the U.S, 5-year survival is about 80% for those with localized disease and about 20% for individuals with metastatic disease [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
