Need for Guidelines for Screening in Anal Cancer: A Lesson From Cervical Cancer

Excerpt

To the Editor—No guidelines currently exist for screening for anal cancer.1 No randomized trials have been reported and what data exists about the subject are not definitive. There is surrender to the notion that in the absence of a clear understanding of the natural history of the disease, screening offers little utility. For this reason, Anderson et al.2 did not support the implementation of a screening program for anal intraepithelial neoplasia (AIN) and anal cancer in homosexual males despite the growing incidence in this patient population and the general population at large. The incidence of anal cancer has increased by almost 40 percent in females.3 There are obvious similarities between the cervical and anal canals. Both possess transitional zones and squamous cell epithelia prone to the carcinogenic potential of the human papillomavirus (HPV). It has been reported that specific HPV haplotypes 16, 51, 53 are responsible for both squamous-cell cancer (SCC) of the anal and cervical canals.4 Females with cervical HPV infection have a threefold increased risk of concurrent anal infection.5 This suggests an infective etiology in the development of SCC in both regions. Indeed, a 26 percent genotype-specific concordance was observed among concurrent anal and cervical infections, further suggesting a common source of infection.5 There are new screening tools in development, and recently Pineda et al.6 reported their experience with high-resolution anoscopy in targeted treatment of high-grade squamous intraepithelial lesions. Vajdic et al.7 in contradistinction reported that blind cytology smears (inserting 4 cm into the anal canal and rotated) were superior to anoscope-guided smears for screening for anal neoplasia. This latter technique is cheaper and identical to that performed for cervical intraepithelial neoplasia (CIN). The implementation of a screening program has successfully reduced the incidence of cervical cancer. This has been largely through identification of specific risk factors for CIN: young females, sexually active with multiple partners, history of chlamydial infection, and frequent alcohol usage.5 With a growing number of bisexuals and males and females engaging in receptive anal intercourse, there is greater possibility for spread of oncogenic HPV haplotypes from cervix to anus. There is likely, therefore, an overlap in the risk factors for both these entities. Screening may be conducted in a similar manner and at the same time as cervical cancer screening. This is of particular importance in young sexually active females with dysplastic cells on Pap smear. Clinical responsibility may soon dictate that clinicians inquire of their female patients regarding receptive anal intercourse. If she reports to engage in this, she should be duly offered an opportunity to undergo anal Pap smear screening. The addition of immunosuppression and HIV infection to this completes a plausible list of putative risk factors for anal cancer that may serve as guidelines for screening. As we strive to identify the association between anal cancer and oncogenic haplotypes, we also must acknowledge the oncogenic potential of theHPV virus that we are implicating and duly screenfor it. In this manner, we may be better equipped to prevent its occurrence altogether rather than wait until we have to treat it. Is it really necessary to have to establish the natural history of this condition merely in response to a pedantic stipulation despite having satisfied all other prerequisites for screening? As we endeavor to demonstrate a common etiology for both cervical and anal cancers, we shouldsee fit to screen for both with equal conviction. …