Anal cancer incidence and survival: the surveillance, epidemiology, and end results experience, 1973-2000

Anal cancer screening behaviors and intentions in men who have sex with men

BACKGROUND

The incidence of anal cancer has increased in the past decade, especially among men who have sex with men (MSM) and HIV-infected individuals. There is controversy about whether to routinely screen for anal cancer in MSM.

OBJECTIVES

To determine whether current anal cancer screening behaviors, intention, and concern differ by HIV serostatus and to identify characteristics of men who intend to seek anal cancer screening.

DESIGN AND PARTICIPANTS

Cross-sectional analysis of data collected from 901 HIV-infected and 1,016 HIV-uninfected MSM from the Multicenter AIDS Cohort Study (MACS) in 2005-2006.

MEASUREMENTS

Self-reported anal cancer screening history, attitudes, and intentions.

RESULTS

A history of anal warts was relatively common in these men (39%), whereas having a recent anal Pap test (5%), intention to seek anal cancer screening in the next 6 months (12%), and concern about anal cancer (8.5%) were less common. Intention to seek anal cancer screening was associated with enabling factors (screening availability, health insurance), need factors (HIV-infection, history of anal warts), concern about anal cancer, and recent sexual risk taking. Among four large US cities, there was significant regional variability in anal cancer screening behaviors, intention, and concern (all p<0.001). Most MSM (76%) indicated they would go to their primary care physician for an anal health problem or question.

CONCLUSIONS

This study demonstrates a low rate of anal cancer screening and intention to screen among MSM. As more evidence emerges regarding screening, primary care physicians should be prepared to discuss anal cancer screening with their patients.

Incidence and epidemiology of anal cancer in the multicenter AIDS cohort study

OBJECTIVE

To examine the incidence and risk factors for anal cancer in a multicenter cohort of human immunodeficiency virus (HIV) positive and HIV-negative men who have sex with men followed between 1984 and 2006 (Multicenter AIDS Cohort Study).

METHODS

Prospective analysis using Poisson regression and Cox proportional hazard models and a nested case-control study using conditional logistic regression.

RESULTS

There were 28 cases of anal cancer among the 6,972 men who were evaluated. The incidence rate was significantly higher in HIV-positive men than in HIV-negative men (incidence rate = 69 vs 14 per 100,000 person-years). Among HIV-positive men, anal cancer incidence was higher in the highly active antiretroviral therapy (HAART) era than the pre-HAART era (incidence rate = 137 vs 30 per 100,000 person-years). In multivariate analysis restricted to the HAART era, anal cancer risk increased significantly with HIV infection (relative hazard = 4.7, 95% confidence interval = 1.3 to 17) and increasing number of unprotected receptive anal sex partners at the first 3 study visits (P trend = 0.03). Among HIV-positive men, current HAART use did not decrease anal cancer risk.

CONCLUSIONS

HIV-positive men had increased risk of anal cancer. Improved survival of HIV-positive individuals after HAART initiation may allow for sufficient time for human papillomavirus-associated anal dysplasias to develop into malignancies, thus explaining the increased incidence of anal cancer in the HAART era.

Tobacco smoking and risk of recurrence for squamous cell cancer of the anus

OBJECTIVE

Squamous cell cancer of the anus is associated with multiple risk factors, including infection with human papillomavirus, immunosuppression, chronic inflammation, and tobacco smoking, although there is little data on these factors for the prediction of recurrent disease. Here, we evaluated the risk of recurrence and mortality of anal carcinoma in association with tobacco smoking.

METHODS

We conducted a retrospective review of cases of anal carcinoma from two local hospitals. We obtained information on treatment response and cancer recurrence, as well as tobacco usage from medical records.

RESULTS

We identified 64 patients with squamous cell cancer of the anus, and 34 of these (53%) had a tobacco smoking history. Current smokers had higher carcinoma recurrence rates (11/34, 32%) than non-smokers (6/30, 20%). Overall mortality was 33% (21/64), and cancer-related mortality was 23% (15/64). Smokers were more likely to die from recurrence than non-smokers, with 45% of smokers dead compared to only 20% of non-smokers by 5 years after treatment.

CONCLUSION

Tobacco smoking appears to be associated with anal carcinoma disease recurrence, and is related to increased mortality. This data suggests that patients should be cautioned about tobacco smoking once a diagnosis of anal carcinoma is made in attempt to improve their long-term outcome.

High-resolution anoscopy targeted surgical destruction of anal high-grade squamous intraepithelial lesions: a ten-year experience

PURPOSE

This study was designed to determine whether high-resolution anoscopy and targeted surgical destruction of anal high-grade squamous intraepithelial lesions is effective in controlling high-grade squamous intraepithelial lesions while preserving normal tissues.

METHODS

Retrospective review of 246 patients with high-grade squamous intraepithelial lesions treated with high-resolution anoscopy-targeted surgical destruction from 1996 to 2006, with at least one follow-up at a minimum two months with physical examination, high-resolution anoscopy, cytology, and biopsy when indicated.

RESULTS

Lesions were extensive in 197 patients (81 percent); 207 (84 percent) were men, and 194 (79 percent) were immunocompromised (HIV or other). Persistent disease occurred in 46 patients (18.7 percent), requiring planned staged therapy; 10 required surgery. Recurrent high-grade squamous intraepithelial lesions occurred in 114 patients (57 percent) at an average 19 (range, 3-92) months; 26 of these required surgery. All other patients were retreated in-office with high-resolution anoscopy-directed therapies. Complications were seen in nine patients (4 percent). Despite treatment, three patients progressed to invasive cancer (1.2 percent). At their last visit, 192 patients (78 percent) had no evidence of high-grade squamous intraepithelial lesions.

CONCLUSIONS

High-resolution anoscopy-targeted destruction combined with office-based surveillance and therapy is effective in controlling high-grade squamous intraepithelial lesions and is superior to reports of expectant management or traditional mapping procedures.

Acquisition of anal human papillomavirus (HPV) infection in women: the Hawaii HPV Cohort study

BACKGROUND

The majority of anal cancer is associated with human papillomavirus (HPV) infection, yet little is known about women's risk of acquisition of anal HPV infection.

METHODS

Risk factors for the acquisition of anal HPV infection were examined in a longitudinal cohort study of 431 women, via repeated measurement of HPV DNA.

RESULTS

Seventy percent of women were positive for anal HPV infection at one or more clinic visits from baseline through a follow-up period that averaged 1.3 years. The incidence of a high-risk (HR) infection was 19.5 (95% confidence interval [CI], 16.0-23.6) per 1000 woman-months. The most common incident HR HPV types were HPV-53, -52 and -16. The presence of an HR anal HPV infection at baseline increased the risk of an incident anal infection by 65%. Baseline HR cervical HPV infection also predicted the acquisition of an HR anal HPV infection (odds ratio, 1.81 [95% CI, 1.09-3.02]). Nonviral risk factors for acquisition of HR HPV infection included younger age, lower socioeconomic status, greater lifetime number of sexual partners, past use of hormones, and condom use.

CONCLUSIONS

The results of this study suggest that women's risk of anal HPV infection is as common as their risk of cervical HPV infection.

Assessing the impact of FDG-PET in the management of anal cancer

PURPOSE

To assess the utility of FDG-PET in anal cancer for staging and impact on radiotherapy planning (RTP), response and detection of recurrent disease.

METHODS AND MATERIALS

Fifty histopathological anal cancer patients were reviewed between 1996 and 2006. The median age was 58 years (range 36-85) with 19 males:31females. Clinical assessment with CT was compared to PET. Impact on management, disease response, recurrence and metastases was evaluated.

RESULTS

The non-PET staging was Stage I(8), Stage II(18), Stage III(22), and Stage IV(2)s. The primary was strongly FDG avid in 98% with non-excised tumors compared to CT (58%). PET upstaged 17% with unsuspected pelvic/inguinal nodal disease. Pre-treatment PET identified 11 additional by involved nodal groups in 48 patients causing RTP amendments in 19%. Post-treatment PETs at median 17 weeks (range 9-28) showed complete responses in 20 (80%) and 5 (20%) partial responses (PR). PRs were biopsy positive in 2 and negative in 3. Fifteen had follow-up scans of which all nine PETs detected recurrences were pathologically confirmed.

CONCLUSIONS

Anal cancer is FDG-PET avid. PET upstages 17% and changes the RTP in 19%. PET can aid in anal cancer staging and identification of residual disease, recurrent/metastatic disease but warrants further prospective studies.

HIV-specific differences in outcome of squamous cell carcinoma of the anal canal: a multicentric cohort study of HIV-positive patients receiving highly active antiretroviral therapy

PURPOSE

To define clinical outcome after definitive chemoradiotherapy (CRT) of anal carcinoma in HIV-infected patients treated with highly active antiretroviral therapy (HAART).

PATIENTS AND METHODS

A multicentric cohort comparison of 40 HIV-positive patients with HAART and 81 HIV-negative patients treated with radiotherapy (RT) or CRT was retrospectively performed. Local disease control (LC), relapse-free survival (RFS), overall survival (OS), cancer-specific survival (CSS), toxicity, and prognostic factors were investigated.

RESULTS

HIV-positive patients were younger (mean age, 48 v 62 years; P < .0005), predominantly male (93% v 25%; P < .0005), and with early-stage (P = .06) and large-cell histology (90% v 67%; P = .005) disease. RT or CRT resulted in complete response in 92% (HIV positive) and 96% (HIV negative) of cases. Five-year OS was 61% (95% CI, 44% to 78%) in HIV-positive and 65% (95% CI, 53% to 77%) in HIV-negative patients (median follow-up, 36 months). Five-year LC was 38% (95% CI, 5% to 71%) in HIV-positive and 87% (95% CI, 79% to 95%) in HIV-negative patients (P = .008) compromising CSS and sphincter preservation. Grade 3/4 acute skin (35% v 17% [HIV negative]; P = .04) and hematologic (33% v 12% [HIV negative]; P = .08) toxicity together approximated 50% in HIV-positive patients. RFS in HIV-positive patients was associated with RT dose (P = .08) and severe acute skin toxicity (P = .04).

CONCLUSION

Long-term LC and acute toxicity represent major clinical challenges in HIV-positive patients with anal carcinoma. Even if fluoropyrimidine-based CRT is feasible and may result in similar response rates and OS as in HIV-negative patients, improved treatment strategies with better long-term outcome are warranted.

Squamous cell carcinoma of the anal canal: utilization and outcomes of recommended treatment in the United States

BACKGROUND

Over the past two decades, recommended treatment for squamous cell carcinoma of the anal canal has shifted from surgery to primary chemoradiation. Resection is now reserved for persistent or recurrent disease. Our objectives were (1) to evaluate treatment trends over the past 20 years, (2) to assess contemporary treatment utilization, and (3) to examine the impact of recommended vs nonguideline treatment on survival.

METHODS

From the National Cancer Data Base (1985-2005), 38,882 patients with anal canal cancer were identified. Regression models were used to assess factors associated with use of nonguideline treatment (vs chemoradiation +/-surgery). Univariate and multivariate methods were used to assess the impact of treatment on survival.

RESULTS

From 1985 to 2005, the use of chemoradiation increased significantly with a concomitant decrease in treatment with surgery alone (P < .0001). However, only 74.9% (5014 of 6696) of patients underwent primary chemoradiation therapy in 2003-2005. Overall, 22.7% (1523 of 6696) of patients received treatment that was not concordant with established guidelines: primary surgery (13.0%) and primary chemotherapy or radiation (9.7%). Patients were significantly less likely to receive guideline treatment if male, older, black or Hispanic, more severe comorbidities, or Stage I (vs Stage II or III). Patients undergoing chemoradiation ( +/- surgery) had higher 5-year survival rates than patients who received nonguideline treatment (64% vs 58%; hazard ratio 0.82, 95% confidence interval [95% CI] 0.77-0.87; P < .0001).

CONCLUSION

Primary chemoradiation therapy has supplanted surgical treatment and is associated with better outcomes; however, nearly a quarter of patients are still receiving treatment that is not concordant with established guidelines.

Human immunodeficiency virus-associated squamous cell cancer of the anus: epidemiology and outcomes in the highly active antiretroviral therapy era

PURPOSE

To evaluate and determine predictors of squamous cell carcinoma of the anus (SCCA) outcomes in the highly active antiretroviral therapy (HAART) era for HIV-positive and -negative individuals using large national Veterans Affairs (VA) Administration databases.

PATIENTS AND METHODS

We used the VA administrative databases to perform a retrospective cohort study in 1,184 veterans diagnosed with SCCA between 1998 and 2004. We calculated HIV infection rates and used logistic regression to identify epidemiologic factors that were associated with HIV infection. Kaplan-Meier curves and Cox proportional hazards models were calculated to compare survival between HIV-positive and HIV-negative veterans.

RESULTS

In our cohort, 175 patients (15%) were HIV positive. The median age of the HIV-negative and -positive patients was 63 and 49 years, respectively (P < .001). Individuals with HIV were eight times more likely to be male (P = .01) and three times more likely to be African American (P < .001). There were no differences between HIV-positive and HIV-negative individuals in the receipt of treatment. The 2-year observed survival rates were 77% and 75% among HIV-positive and HIV-negative individuals, respectively. In multivariate Cox analysis, significant predictors of survival were age, sex, metastasis at diagnosis, and comorbidity score. HIV infection did not affect survival.

CONCLUSION

A noteworthy proportion of individuals with SCCA in the VA system are HIV positive. HIV-associated SCCA seems mainly to be a disease among younger men. Survival of SCCA is equivalent between HIV-positive and HIV-negative individuals in the HAART era. Treatment should not be withheld or deintensified based on HIV status.

Squamous-cell carcinoma of the anal canal: predictors of treatment outcome

PURPOSE

The incidence of anal canal squamous-cell carcinoma is increasing. Limited data exist on predictors of treatment failure. This study was designed to identify predictors for relapse/persistence after first-line therapy.

METHODS

Using one database, we identified 131 Stages I-III patients treated for primary anal canal squamous-cell carcinoma at our institution from December 1986 to August 2006, with minimum six-month follow-up. Demographic, pathologic, treatment, and outcome data were extracted. Treatment failure was defined as biopsy-proven persistence or relapse (local and/or distant). Univariate, bivariate, and multivariate survival analyses were performed.

RESULTS

Of 131 patients (median age, 58.3 years; median follow-up, 2.9 (range, 0.6-11.2) years), 66 percent were females, 43.5 percent were Stage II, and 11 (8 percent) were HIV-positive. Surgery only (local excision) was uncommon (6.9 percent, n=9). One hundred twenty-two patients (93.1 percent) received radiotherapy; two required preradiotherapy diversion. Although 114 (93.4 percent) completed radiotherapy, most required treatment breaks, making total duration of radiotherapy longer than planned. Almost all patients undergoing radiotherapy (96.7 percent, 118/122) also had chemotherapy: 118 (100 percent, Stages I-III) had concurrent chemotherapy: (98 (83.8 percent) mitomycin/5-fluorouracil, 12 (10.2 percent) cisplatin/5-fluorouracil, 8 (6.8 percent) 5-fluorouracil alone); 35 of 46 (76 percent) Stage III patients received induction chemotherapy (34 (97.1 percent) cisplatin/5-fluorouracil, 1 (2.8 percent) 5-fluorouracil alone). Many (44 percent Stages I/II, 48.9 percent Stage III) required dose adjustments. Thirty-seven patients (28.2 percent) failed first-line therapy. There were no differences between patients with relapse (n=22) or persistence (n=15) of disease. Bivariate analyses demonstrated that T stage (P=0.0019), completion of radiotherapy, and total radiotherapy dose (P=0.03) were all significantly associated with treatment failure. On multivariate analyses, disease stage (P=0.05) and completion of radiotherapy (P=0.01) remained significant predictors of relapse-free survival.

CONCLUSIONS

Tolerance of chemoradiation seems to be an important predictor of treatment success. Effective therapies with less acute toxicity must be identified.

Prevalence of anal cytologic abnormalities in a French referral population: a prospective study with special emphasis on HIV, HPV, and smoking

PURPOSE

Studying anal cytology to detect intraepithelial neoplasia has been demonstrated to be useful in highly selected populations. This study was designed to determine the frequency of abnormal smears in a wide sample of patients consulting for anorectal symptoms.

METHODS

An anal smear was proposed during each consultation during a three-month period.

RESULTS

A total of 205 patients (112 females) were included. After the consultation, visible condylomas were detected in 12 (6 percent) of the cases. Two hundred three (99 percent) smears were able to be analyzed. No case of high-grade squamous intraepithelial lesion was found. Four cases of low-grade squamous intraepithelial lesion were found, all in HIV patients with a history of condylomatous lesions. Forty smears were interpreted as atypical squamous cells of undetermined significance and 159 were normal. The prevalence in this population of low-grade squamous intraepithelial lesion was 19 percent (4/21) in HIV seropositive males, and 15 percent (4/26) in the case of a past history of condyloma. The factors associated with an abnormal smear (low-grade squamous intraepithelial lesion or atypical squamous cells of undetermined significance) were a history of anal condylomatous lesions (odd ratio, 4.9; range, 2.1-11.5), HIV seropositivity (odd ratio, 4; range, 1.6-9.9), and smoking (odd ratio, 2.1; range, 1.1-11.5).

CONCLUSIONS

This work confirms that the frequency of low-grade squamous intraepithelial lesion is raised in HIV-seropositive males and also where there is a history of condyloma, which corroborates the necessity for regular monitoring and screening of these patients at risk. This study also suggests that the use of tobacco is associated with anal cytologic abnormalities.

Anal human papillomavirus testing with Digene's hybrid capture 2 using two different sampling methods

PURPOSE

The incidence of human papillomavirus detection in the anal canal is rising. Efficient anal screening by cytology is hampered because of poor specificity. Human papillomavirus (HPV) testing is proposed in addition to Papanicolaou (Pap) testing for the detection of cervical neoplasia. The purpose of this study was to determine the usefulness of a human papillomavirus-DNA detection test to detect human papillomavirus-associated disease and to compare two different methods of sample collection.

METHODS

In 555 patients, anal samples were obtained by using a cervical brush and a Dacron swab to test for high-risk and low-risk human papillomavirus-DNA. Patients positive for human papillomavirus-DNA underwent anoscopy. Biopsies were taken from visible lesions.

RESULTS

Low-risk human papillomavirus-DNA was found in 325 of 555 patients (58.6 percent) and high-risk human papillomavirus-DNA in 285 of 555 patients (51.4 percent). Positive results confined to one single test method were higher for Dacron swab sampling (2.3 vs. 4.3 percent for low-risk human papillomavirus, P < 0.0001; 3.1 vs. 4.9 percent for high-risk human papillomavirus, P < 0.001). A positive correlation of relative light units was found for both sampling methods in the total cohort (P < 0.0001) as well as for patients who tested human papillomavirus-positive by both sampling techniques (P < 0.0001). Sampling with Dacron swabs yielded higher relative light units values compared with sampling with cervical brush for low-risk human papillomavirus-DNA and high-risk human papillomavirus-DNA.

CONCLUSIONS

Anal screening for human papillomavirus-DNA by hybrid capture 2 is a useful method for detection of human papillomavirus-associated disease. Sample collection using Dacron swabs identifies more human papillomavirus-positive patients, and yields higher relative light unit values than using the cervical brush. Further studies are needed to determine the exact value of hybrid capture 2 in the screening for (pre)cancerous lesions of the anal canal.

Activation of AKT and nuclear accumulation of wild type TP53 and MDM2 in anal squamous cell carcinoma

Human papilloma virus (HPV) infection is considered as an important aetiological factor for anal squamous cell carcinoma (ASCC) but is not sufficient for tumour progression. This carcinoma is poorly understood at the molecular level. Using the largest cohort of cases to date we investigated the molecular mechanisms underlying ASCC development, in particular the roles of TP53, MDM2 and AKT. Viral infection in our cohort occurred at high frequency (73%, 94/128) with HPV16 accounting for the majority (86%, 81/94) of infected cases. Only 4% (5/119) of ASCCs showed TP53 (exons 5-8) mutations, but a high frequency (91%, 100/110) of nuclear protein expression of TP53 was observed. There was a significant association (p < 0.001) between nuclear accumulation of TP53 and MDM2 protein although no MDM2 mutations were found, and copy number was normal. Cellular accumulation of phosphorylated-AKT was observed in 66% (82/125) of ASCCs and an association demonstrated between nuclear accumulation of MDM2 and activated AKT (p < 0.001). We observed a high frequency of copy number gain at PIK3CA (47%), and some coding sequence mutations (4%). Amplification of PIK3CA was associated with presence of phosphorylated-AKT (p= 0.008). There was no association between virus infection and TP53 nuclear accumulation (p = 0.5). However, a significant association was found between infection and MDM2 nuclear staining, and between infection and activated AKT (p = 0.04, p = 0.01, respectively). We propose that activation of AKT, possibly through the PI3K-AKT pathway, is an important component of ASCC tumorigenesis that contributes to MDM2 and TP53 accumulation in the nucleus.

Early impact and performance characteristics of an established anal dysplasia screening program: program evaluation considerations

BACKGROUND

Screening for invasive anal cancer and its precursors is being increasingly advocated as a response to increasing incidence among HIV-infected persons. We implemented a comprehensive screening program in 2001 and report our early experience to inform monitoring and evaluation of such programs. Our research aims were: (1) to estimate incidence of and mortality from invasive anal cancer (IAC) before (1995-2000) and after (2001-2005) screening program implementation and (2) to examine potential screening program quality indicators.

METHODS

The study cohort included all patients under care for HIV infection at UCSD Owen Clinic between 1995-2005. Person-time incidence rates (IR) and case survival of IAC were estimated for the pre-screening (1995-2000) and post-screening (2001-2005) periods. High resolution anoscopy (HRA) operator accuracy was estimated by kappa agreement between cyto-histologic comparisons. Program quality indicators included: (1) screening coverage; (2) percent technically unsatisfactory cytology smears; (3) time between 1st abnormal cytology and 1st HRA; and (4) time between last clinic visit and last cytology.

RESULTS

28 cases of IAC and 13,411 person-years were observed between 1995-2005. IRs (95% CI) pre-screening and post-screening were 199 and 216 per 100,000 person-years, respectively. There was no routine treatment of high grade squamous intraepithelial lesions (HSIL) during the study period. The percent of patients with IAC requiring chemoradiation decreased from 90.9% to 70.6% (p=0.36). There was a significant improvement in cyto-histologic agreement at HRA with increasing operator experience (r=0.92, p=0.025). Screening coverage was 73% of the target population. Among 14 providers, the percent unsatisfactory cytology smears averaged 27% but varied from 0 - 62%. The median time from 1st abnormal cytology to 1st HRA was 258 days. The median interval between the last cytology and the last clinic visit was 207 days.

CONCLUSION

(1) The overall IR of IAC did not decline in the screening era and was higher than previous estimates for HIV cohorts; (2) stage shift to IAC of more favorable prognosis is a reasonable screening goal; (3) HRA accuracy varied by provider experience; (4) because of delay in access to HRA, digital rectal exam should be combined with cytology screening to detect palpable disease.

Tumor-infiltrating cytotoxic T cells but not regulatory T cells predict outcome in anal squamous cell carcinoma

PURPOSE

Tumor-infiltrating lymphocytes (TIL) are a possible prognostic factor in solid tumors. Cytotoxic TILs are generally considered as prognostically favorable, whereas regulatory T cells (Treg) may have adverse effects by virtue of their ability to inhibit effector cells. We have evaluated the effect of T-cell subsets on survival in patients with anal squamous cell carcinoma following radiochemotherapy.

METHODS

Biopsy specimens from 38 patients with anal carcinomas were evaluated using tissue microarrays and immunohistochemistry for the presence of tumor-infiltrating immune cells using CD3, CD4, CD8, and CD68 antibodies. Treg were identified using an antibody directed against the transcription factor FoxP3, and granzyme B served as a marker for cytotoxic cells. Intratumoral immune cells were enumerated using a semiautomatic image analysis program. Prognostic effect of TIL subsets was evaluated by the log-rank test comparing no evidence of disease survival for groups with high and low numbers using median values as cutoff.

RESULTS

CD3+ and CD4+ TILs influenced no evidence of disease survival: 3-year rates for patients with low numbers were 89% and 95%, respectively, and 54% (P = 0.02) and 48%, (P = 0.01), respectively, in cases with high numbers. Large numbers of tumor-infiltrating granzyme B+ cytotoxic cells had a significant negative prognostic effect (P = 0.008), whereas no effect was observed for Treg.

CONCLUSIONS

TILs were identified as negative prognostic indicators in anal squamous cell carcinomas with granzyme B+ cytotoxic cells showing highest effect on outcome. This is possibly explained by the selection of therapy-resistant tumor cell clones. No prognostic influence of Treg was found. Knowledge of local immune responses is important for the development of immunotherapeutic strategies.

Tumor response and survival predicted by post-therapy FDG-PET/CT in anal cancer

PURPOSE

To evaluate the response to therapy for anal carcinoma using post-therapy imaging with positron emission tomography (PET)/computed tomography and F-18 fluorodeoxyglucose (FDG) and to compare the metabolic response with patient outcome.

PATIENTS AND METHODS

This was a prospective cohort study of 53 consecutive patients with anal cancer. All patients underwent pre- and post-treatment whole-body FDG-PET/computed tomography. Patients had been treated with external beam radiotherapy and concurrent chemotherapy. Whole-body FDG-PET was performed 0.9-5.4 months (mean, 2.1) after therapy completion.

RESULTS

The post-therapy PET scan did not show any abnormal FDG uptake (complete metabolic response) in 44 patients. Persistent abnormal FDG uptake (partial metabolic response) was found in the anal tumor in 9 patients. The 2-year cause-specific survival rate was 94% for patients with a complete vs. 39% for patients with a partial metabolic response in the anal tumor (p = 0.0008). The 2-year progression-free survival rate was 95% for patients with a complete vs. 22% for patients with a partial metabolic response in the anal tumor (p < 0.0001). A Cox proportional hazards model of survival outcome indicated that a complete metabolic response was the most significant predictor of progression-free survival in our patient population (p = 0.0003).

CONCLUSIONS

A partial metabolic response in the anal tumor as determined by post-therapy FDG-PET is predictive of significantly decreased progression-free and cause-specific survival after chemoradiotherapy for anal cancer.

Update: human papillomavirus infection remains highly prevalent and persistent among HIV-infected individuals

PURPOSE OF REVIEW

Human papillomavirus infections and human papillomavirus-associated anogenital tumors are more prevalent in HIV-infected than HIV-uninfected individuals. This review focuses on recent developments related to human papillomavirus burden in HIV-infected individuals; anogenital human papillomavirus types and type-specific differences in the natural history of human papillomavirus infections; the effect of highly active antiretroviral therapy on human papillomavirus infection; and novel human papillomavirus therapeutic interventions.

RECENT FINDINGS

There is a paucity of recent data on the effect of highly active antiretroviral therapy on human papillomavirus infection and its related anogenital abnormalities/cancer. Review articles on the molecular biology of human papillomavirus in HIV infection outline why, despite highly active antiretroviral therapy, anogenital tumors may continue to increase in this population. Studies continue to confirm the high prevalence of human papillomavirus infection and to define the different human papillomavirus types correlated with anogenital cytologic abnormalities, an important area in light of the development of an effective type-specific human papillomavirus vaccine.

SUMMARY

Anogenital human papillomavirus infection remains highly prevalent and persistent in HIV-infected individuals. HIV is associated with a wide diversity of human papillomavirus types and a high prevalence of anogenital cytologic abnormalities. The incidence of anogenital human papillomavirus-related cancers remains high in the highly active antiretroviral therapy era, raising concerns of human papillomavirus infections as a rising health burden among HIV-infected individuals. Interventions aimed at preventing human papillomavirus infections with vaccinations need to be evaluated in HIV-infected individuals.

Anal intraepithelial neoplasia and anal cancer in dermatological practice

Anal intraepithelial neoplasia is considered to be a precursor lesion of invasive anal cancer. It is now increasingly recognized in high-risk groups, such as men who have sex with men and HIV-infected patients. Human papillomaviruses are considered to be an important aetiological agent in both anal intraepithelial neoplasia and anal cancer. Dermatologists are likely to encounter these conditions among the differential diagnoses to be considered in high-risk patients presenting with perianal and anal lesions. Anal cancer rates are also increasing among the HIV-infected and HIV-non-infected population. The successful treatment of anal intraepithelial neoplasia may reduce the risk of subsequent development of anal cancer. However, current therapies for anal intraepithelial neoplasia may be associated with treatment-related morbidity and are not well validated. It is currently not proven that they reduce the likelihood of the development of anal cancer. Nevertheless, screening for anal intraepithelial neoplasia is being advocated for high-risk groups and may become standard dermatological care for these patients. In view of recent developments in the understanding of this condition, this article reviews the current understanding of anal intraepithelial neoplasia and its treatment from a dermatological perspective.

Prevalence and risk factors for anal cytologic abnormalities and human papillomavirus infection in a rural population of HIV-infected males

PURPOSE

This study was designed to determine the prevalence and risk factors for anal squamous intraepithelial lesions and human papillomavirus infection in a rural population of HIV-infected males.

METHODS

A cross-sectional study was performed. Risk factors were collected. Anal Papanicolaou smear and human papillomavirus screening for oncogenic types were performed.

RESULTS

Of 211 eligible male patients, 149 (70.6 percent) participated. HIV transmission risk was predominantly males who have sex with males (82 percent). The mean duration of HIV infection was 9.9 years. Ninety (60 percent) males had abnormal anal cytology, including atypical cells of unknown significance 40 (26 percent), low-grade squamous intraepithelial lesions 28 (19 percent), and high-grade squamous intraepithelial lesions 22 (15 percent). Human papillomavirus was detected in 61 percent. Binary logistic regression adjusted risks for abnormal anal cytology included: males who have sex with males (P<0.001), human papillomavirus infection (P<0.001), history of anogenital warts (P=0.014), and the mean lowest CD4 count (abnormal cytology, 158 (standard deviation, 135), negative cytology, 208 (standard deviation, 180; P=0.017)). Twenty-two patients with high-grade squamous intraepithelial lesions underwent colorectal surgical examination and anoscopy. Two (10 percent) were found to have invasive squamous-cell carcinoma and three (15 percent) others had mass lesions with high-grade squamous intraepithelial lesions.

CONCLUSIONS

Anal squamous intraepithelial lesions and oncogenic human papillomavirus are highly prevalent in males infected with HIV and living in a rural setting.

What do gay men know about human papillomavirus? Australian gay men's knowledge and experience of anal cancer screening and human papillomavirus

OBJECTIVE

The objective of this study was to determine levels of experience and knowledge concerning anal dysplasia, anal Pap smear tests, and human papillomavirus (HPV) among gay and other homosexually active men.

STUDY DESIGN

Three hundred eighty-four men attending a large gay community event in Melbourne completed a short survey.

RESULTS

Ninety-two percent identified as gay and 4.8% as bisexual. A total of 6.4% were HIV-positive and a further 3.5% did not know their HIV status. On a range of measures, it was clear that the men knew very little about anal cancer (19% scored zero on a 12-point knowledge scale) and virtually nothing about HPV (47% scored zero on an 8-point knowledge scale). A total of 55.1% had never heard of an anal Pap smear and 44.8% had ever heard of HPV; 56.4% did not know whether it affected men and/or women.

CONCLUSIONS

The test for anal dysplasia is still largely unknown among Australian gay men and they currently have poor sense of personal susceptibility to the disease. Health education strategies are suggested to improve this situation.

The presentation of anogenital cancers as sexually transmissible infection: a case for vigilance

The recent outbreaks of sexually transmissible infections (STI) provoke professional concern and public anxiety. There is sporadically published literature reporting cases of vulval, penile and anal cancers presenting at genitourinary medicine clinics. The recent referral of a series of cases, by medical practitioners, as anogenital warts, which were later diagnosed as vulval, penile and anal cancers, is alarming. The cases reflect the current state of apprehension between patients and medical professionals regarding STI.

Bilan préthérapeutique initial du carcinome épidermoïde invasif de l’anus

Anal epidermoid carcinoma is a rare malignant tumor, comprising less than 5% of all carcinomas of the colon, rectum, and anus. The primary therapy now includes radiotherapy, often in combination with chemotherapy. Radical surgery is now rarely indicated. Therapeutic indications are based on locoregional staging, the presence of visceral metastases and an evaluation of the medical history. Anorectal endosonography is helpful in evaluating locoregional extension. In addition, magnetic resonance imaging, positron emission tomography scanning and inguinal sentinel lymph node procedure should play a role in a more selective approach in patients with anal carcinoma.

Anal cancer in renal transplant patients

PURPOSE

A comprehensive literature review was performed to examine the prevalence of anal cancer, anal intraepithelial neoplasia (AIN) and anal human papillomavirus (HPV) infection in renal transplant recipients who are at risk of anal cancer due to iatrogenic immunosuppression.

METHODS

Pertinent articles were identified from searches performed on the National Center for Biotechnology Information database using the following keywords: anal cancer, AIN, screening, renal transplant (or kidney transplant), organ transplant recipients and post-transplant malignancies.

RESULTS

The prevalence of AIN is 20% in renal transplant patients. The prevalence of anal HPV infection in established transplant patients is 47%, and the prevalence of anal HPV infection in new transplant patients is 23%. The relative risk for anal cancer in renal transplant patients is 10.

CONCLUSIONS

As compared to HIV-positive male patients who practise anal intercourse, renal transplant patients showed a modest rise in relative risk for anal cancer. Screening programmes to detect AIN in HIV-positive patients who practise anal intercourse have been introduced on a preliminary basis in sexual health clinics in the US and may become standard practise in this population. The case for screening in renal transplant patients is unclear and would merit further investigation, especially with reference to the prevalence of anal HPV infection in this population. It may transpire that renal transplant patients would benefit more from HPV prophylaxis rather than screening for AIN.

AIDS malignancies

Among individuals with HIV-infection, coinfection with oncogenic viruses including EBV, HHV-8, and HPV cause significant cancer-related morbidity and mortality. It is clear that these viruses interact with HIV in unique ways that predispose HIV-infected individuals to malignant diseases. In general, treatment directed specifically against these viruses does not appear to change the natural history of the malignant disease, and once the malignancy develops, if their health permits, HIV-infected patients should be treated using similar treatment protocols to HIV-negative patients. However, for the less frequent HIV-related malignancies, such as PEL, or MCD, optimal treatments are still emerging. For certain AIDS-defining malignancies, it is clear that the widespread access to HAART has significantly decreased the incidence, and improved outcomes. However, for other cancers, such as the HPV-related tumors, the role of HAART is much less clear. Further research into prevention and treatment of these oncogenic virally mediated AIDS-related malignancies is necessary.

Anal carcinoma of the elderly treated with radiotherapy alone or with concomitant radio-chemotherapy

PURPOSE

To analyse the results achieved with radio-chemotherapy (RTCT) or radiotherapy alone (RT) in elderly patients (pts) affected with squamous cell anal cancer.

METHODS AND MATERIALS

From 1990 to 2002, 62 pts aged > or =70 years were treated with RT (14) or RTCT (48). There were 9 stage I, 29 stage II, 11 stage IIIa and 13 stage IIIb. MMC+5FU was given concomitantly with RT in an early period, later replaced by Cddp+5FU. In the RTCT group, 36Gy were delivered to pelvic+inguinal lymph nodes, with a tumor boost (18Gy).

RESULTS

Stage II fared significantly better than stage III in terms of locoregional control (LRC) but not overall survival (OS). Pts treated with RTCT had improved LRC, but not OS. LRC was 81% at 3 and 5 years for the RTCT group; the RT group had a LRC of 61% at 3 years. There were more locoregional relapses in the MMC group (29%) versus the Cddp group (19%) and in pts treated with a split (32%) versus no split (19%). No G3 acute toxicity was observed in the RT group; in the RTCT group 15 pts (31%) developed a G3+ acute toxicity. G3+ late damage occurred in 2 pts in the RT only group and in 3 pts in the RTCT group.

CONCLUSIONS

Elderly people considered fit for RTCT should undergo the same schedules used for younger people. MMC or Cddp+5FU are feasible in the elderly, even without a planned split.

Anal cancer: current and future methodology

Despite the small number of patients affected by carcinoma of the anal canal it remains one of the most challenging cancers to treat. For although it is one of the few malignancies that may be cured with chemoradiation alone, the use of combined modality therapy may result in significant treatment-related morbidity. Novel approaches currently are underway in this select patient population and will be addressed for the purposes of this manuscript.

High risk of colostomy with primary radiotherapy for anal cancer

BACKGROUND

Radiotherapy (RT) has become the primary treatment of choice for anal cancer in an effort to avoid colostomy. The current role of surgery appears generally to be underestimated, since diverting colostomy or abdominoperineal resection still often seems to be necessary for complications and local treatment failure after RT.

METHODS

The data of 83 patients primarily treated by RT with curative intent throughout a 20-year period in our institute were analyzed regarding the need for colostomy.

RESULTS

Totally, 28 patients (34%) required creation of a colostomy after primary RT for local failure or treatment-related complications during a mean follow-up period of 39 months. The 3-year actuarial colostomy-free rate was 59% (mean 85 +/- 9 months). Early stage disease, low T-score and absence of infiltration in adjacent organs were associated with a reduced need for colostomy in univariate analysis. In multivariate analysis only T-score was an independent variable in predicting prolonged colostomy-free interval. In this study, no statistically significant differences were noted for gender, age, nodal status, total radiation dose, radiation boost and concurrent chemotherapy.

CONCLUSIONS

In approximately one-third of the patients treated by anal sphincter saving management with curative aimed primary RT, the creation of a colostomy appeared to be necessary for RT complications and local treatment failure. Therefore, patients should be well informed regarding the considerable risk of need for colostomy after RT for anal cancer.

Illustrated instructions for self-collection of anorectal swab specimens and their adequacy for cytological examination

BACKGROUND

Self-collection of anorectal swab specimens would facilitate screening for anal cancer precursors and sexually transmitted rectal infections among men who have sex with men (MSM). However, pictorial guides for self-collection were not previously available.

GOALS

Develop and field test a set of illustrated self-collection instructions.

DESIGN

Cross-sectional study of community-recruited MSM who were naïve with regard to collection of specimens for anal cytology.

RESULTS

Among 222 self- and clinician-collected swab pairs provided by mostly human immunodeficiency virus (HIV)-1 seronegative MSM (median age, 31.5 years), most specimens were adequate for cytologic evaluation, though self-collected swabs were less likely to be so (83% versus 92%, P = <0.001). The illustrated instructions were reportedly essential, but having used them, men rated their understanding of the self-collection procedure as very high.

CONCLUSIONS

Provided with illustrated instructions, most MSM who are naïve to the technique can self-collect anorectal swab specimens that are suitable for screening.

Survival from rectal and anal cancers in England and Wales, 1986–2001

The aim of this study was to investigate the effects of tumour and patient characteristics on trends in the survival of patients with cancer of the anus or rectum in England and Wales. A total of 132,542 adults (15-99 years) who were diagnosed during the 14 years 1986-1999 were followed up to 2001 through the National Health Service Central Register. Relative survival up to 5 years after diagnosis was estimated, using deprivation-specific life tables. Generalised linear models were used to estimate relative excess risks of death, adjusted for patient and tumour characteristics. The results showed that 5-year relative survival was higher in women, younger patients and more affluent patients, and higher for anal cancer than rectal cancer. Survival improved by more than 10% from the late 1980s (around 38%) to the late 1990s (49%). This trend was not explained by changes in the distribution of age, anatomical site, morphology or deprivation. The trend was more marked in younger and more affluent patients, and for adenocarcinoma and epidermoid carcinoma than for tumours with other morphology. The inequality in survival between affluent and deprived patients widened. It is concluded that improvements in survival may reflect improvements in disease stage, diagnostic technique or treatment. Which of these factors contribute to the widening socioeconomic inequalities in survival remains to be elucidated.

Screening HIV-infected individuals for anal cancer precursor lesions: a systematic review

Individuals with human immunodeficiency virus (HIV) infection are at increased risk for human papillomavirus-related squamous cell cancer of the anus. Screening HIV-infected patients for squamous cell cancer of the anus and human papillomavirus-related anal dysplasia may prevent excess morbidity and mortality. We have conducted a systematic review of the indirect evidence in the literature regarding the utility of anal Papanicolau (Pap) smear screening of HIV-infected individuals in the highly active antiretroviral therapy era. Although there are no published studies evaluating the efficacy of anal Pap smear screening for preventing squamous cell cancer of the anus or anal intraepithelial neoplasia, we reviewed data regarding the burden of disease, anal Pap smear sensitivity and specificity, the prevalence of anal dysplasia, and 1 cost effectiveness study. The available evidence demonstrates that HIV-infected individuals have an increased risk for squamous cell cancer of the anus and anal intraepithelial neoplasia. This review identifies important areas for further study before routine anal Pap smear screening can be recommended.

Increasing incidence of squamous cell carcinoma of the anus in Scotland, 1975-2002

In Scotland, since 1975–1979 (world) age-standardised incidence of squamous cell carcinoma of the anus has more than doubled, reaching 0.37 per 100 000 in males and 0.55 in females during 1998–2002, being somewhat higher in socioeconomically deprived areas.

FDG-PET/CT in the evaluation of anal carcinoma

PURPOSE

Surgical staging and treatment of anal carcinoma has been replaced by noninvasive staging studies and combined modality therapy. In this study, we compare computed tomography (CT) and physical examination to [(18)F]-fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) in the staging of carcinoma of the anal canal, with special emphasis on determination of spread to inguinal lymph nodes.

METHODS AND MATERIALS

Between July 2003 and July 2005, 41 consecutive patients with biopsy-proved anal carcinoma underwent a complete staging evaluation including physical examination, CT, and 2-FDG-PET/CT. Patients ranged in age from 30 to 89 years. Nine men were HIV-positive. Treatment was with standard Nigro regimen.

RESULTS

[(18)F]-fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) detected 91% of nonexcised primary tumors, whereas CT visualized 59%. FDG-PET/CT detected abnormal uptake in pelvic nodes of 5 patients with normal pelvic CT scans. FDG-PET/CT detected abnormal nodes in 20% of groins that were normal by CT, and in 23% without abnormality on physical examination. Furthermore, 17% of groins negative by both CT and physical examination showed abnormal uptake on FDG-PET/CT. HIV-positive patients had an increased frequency of PET-positive lymph nodes.

CONCLUSION

[(18)F]-fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography detects the primary tumor more often than CT. FDG-PET/CT detects substantially more abnormal inguinal lymph nodes than are identified by standard clinical staging with CT and physical examination.

Randomized clinical evaluation of self-screening for anal cancer precursors in men who have sex with men

Background

Self-collection of anorectal swab specimens could greatly facilitate the completion of prerequisite studies and future implementation of anal cancer screening among men who have sex with men (MSM). We therefore compared self- versus clinician- collection procedures with respect to specimen adequacy for cytological evaluation, concordance of paired cytological results, and concordance of cytological with biopsy results.

Methods

Paired self- and clinician- collected anorectal Dacron^® swabs for liquid-based (Thin Prep^®) cytological evaluation were collected in random sequence from a mostly HIV-1 seronegative cohort of young MSM in Vancouver. Slides were reviewed by one cytopathologist. Presence of any cytological abnormality (atypical squamous cells of uncertain significance, ASCUS, or above) prompted referral for high-resolution anoscopy and possible biopsy.

Results

Among 222 patient-clinician specimen pairs, most were adequate for cytological evaluation, though self-collected specimens were less likely to be so (83% versus 92%, McNemar's test p < 0.001). Cytological abnormalities, noted in 47 (21%) of self-collected and 47 (21%) of clinician-collected specimens (with fair agreement, kappa = 0.414) included, respectively: ASCUS (5%, 5%), and low-grade (13%, 13%) and high-grade (3%, 3%) squamous intraepithelial lesions. Among 12 men with biopsy-confirmed high-grade neoplasia, most had abnormal cytological results (including 6 patient and 9 clinician swabs) but few (2 patient and 1 clinician swab) were high-grade.

Conclusion

Self-collection of anorectal swab specimens for cytologic screening in research and possibly clinical settings appears feasible, particularly if specimen adequacy can be further improved. The severity of biopsy-confirmed anorectal disease is seriously underestimated by cytological screening, regardless of collector.

Anal human papillomavirus infection in women and its relationship with cervical infection

Human papillomavirus (HPV), the primary cause of cervical cancer, is also associated with the development of anal cancer. Relatively little is known about the epidemiology of anal HPV infection among healthy females and its relationship to cervical infection. We sought to characterize anal HPV infection in a cohort of adult women in Hawaii. Overall, 27% (372 of 1,378) of women were positive for anal HPV DNA at baseline compared with 29% (692 of 2,372) with cervical HPV DNA. Among women with paired anal and cervical samples, anal infection without accompanying cervical infection was observed in 14% (190 of 1,363). Concurrent anal and cervical HPV infections were observed in 13% (178 of 1,363) of women. Women with cervical HPV infection had >3-fold increased risk of concurrent anal infection. Concurrent anal and cervical HPV infection was most prevalent among the youngest women and steadily decreased through age 50 years. By contrast, the prevalence of anal infection alone remained relatively steady in all age groups. Compared with cervical infections, the overall distribution of HPV genotypes in the anus was more heterogeneous and included a greater proportion of nononcogenic types. A high degree of genotype-specific concordance was observed among concurrent anal and cervical infections, indicating a common source of infection. Nevertheless, the association of anal intercourse with anal HPV infection was limited to those women without accompanying cervical infection. The relationship of anal to cervical infection as described in this study has implications for the development of anal malignancies in women.

Length of human immunodeficiency virus disease and not immune status is a risk factor for development of anal carcinoma

BACKGROUND

The anal epithelium is subject to dysplastic change in patients with human immunodeficiency virus (HIV). We sought to determine if the duration of HIV disease or the patient's immune status were associated with the development of anal carcinoma.

METHODS

HIV-positive patients diagnosed with anal neoplasms were reviewed. Statistical analysis was performed via an unpaired Student t test and the Fisher exact test.

RESULTS

Fourteen patients were identified, 7 with anal intraepithelial neoplasms (group 1) and 7 with anal carcinoma (group 2). Human papillomavirus was detected in 100% of patients in group 1 and in 67% of patients in group 2. There was no significant difference in the level of immunosuppression as assessed by the CD4 counts (266.9 +/- 48.5 vs. 274.7 +/- 92.0 cell/c microl; P = .94) and viral loads (19,243 +/- 18,034 vs. 67,140 +/- 39,570 RNA/mL; P = .29) between groups 1 and 2, respectively. Group 2 had been HIV positive for a significantly longer period of time (12.6 +/- 2.3 y) compared with group 1 (5.9 +/- 2.0 y, P = .05).

CONCLUSIONS

The most significant factor for the development of invasive anal carcinoma in patients with HIV is duration of disease. As a result of improved long-term survival secondary to new HIV therapy, anal invasive carcinoma will become an increasing problem.

Anal screening cytology

This issue of CytoJournal contains an article on screening for anal intraepithelial neoplasia in high-risk male patients. This accompanying Editorial focuses on current understanding of this relatively new disease entity, with insights as to the potential role of screening cytopathology in the epidemiology, pathophysiology and clinical management of this HIV and HPV related anal lesion, which predominates in male patients living long-term with AIDS. Mention is made of techniques of obtaining samples, methods of preparation, and morphologic classification. Issues of anoscopic confirmation, as well as topical and surgical management are emphasized. The similarity of initial experiences in anal screening to problems encountered early in cervical cancer screening programs several decades ago, are highlighted.

Human papillomavirus, smoking, and sexual practices in the etiology of anal cancer

BACKGROUND

The incidence of anal cancer has increased among both men (160%) and women (78%) from 1973 to 2000 in the U.S. The authors conducted a population-based case-control study of anal cancer to examine factors that may account for this increase.

METHODS

Men (n = 119 patients) and women (n = 187 patients) who were diagnosed with anal cancer between 1986 and 1998 in the Seattle area were ascertained through the local Surveillance, Epidemiology, and End Results registry. Control participants (n = 1700) were ascertained through random-digit telephone dialing. Participants were interviewed in person and provided blood samples. Archival tumor tissue was tested for human papilloma virus (HPV) DNA, and serum samples were tested for HPV type 16 (HPV-16).

RESULTS

Overall, 88% of tumors (all histologies) in the study were found to be positive for HPV. HPV-16 was the most frequent HPV type detected (73% of all tumors), followed by HPV-18 (6.9%), regardless of gender. However, 97.7% of tumors from men who were not exclusively heterosexual contained HPV DNA. The risk of anal cancer increased among men (odds ratio [OR], 5.3; 95% confidence interval [95% CI], 2.4-12.0) and women (OR, 11.0; 95% CI, 5.5-22.1) who had > or = 15 sexual partners during their lifetime. Among men who were not exclusively heterosexual and women, receptive anal intercourse was related strongly to the risk of anal cancer (OR, 6.8 [95% CI, 1.4-33.8] and OR, 2.2 [95% CI, 1.4-3.3], respectively). Current smokers among men and women were at particularly high risk for anal cancer, independent of age and other risk factors (OR, 3.9 [95% CI, 1.9-8.0] and OR, 3.8 [95% CI, 2.4-6.2], respectively).

CONCLUSIONS

The high proportion of tumors with detectable HPV suggests that infection with HPV is a necessary cause of anal cancer, similar to that of cervical cancer. Increases in the prevalence of exposures, such as cigarette smoking, anal intercourse, HPV infection, and the number of lifetime sexual partners, may account for the increasing incidence of anal cancer in men and women.