Li C. Cheung

Cervical cancer risk for women undergoing concurrent testing for human papillomavirus and cervical cytology: a population-based study in routine clinical practice

BACKGROUND Concurrent testing for human papillomavirus (HPV) and cervical cytology (co-testing) is an approved alternative to cytology alone in women aged 30 years and older. We aimed to assess the safety in routine clinical practice of 3-year screening intervals for women testing negative for HPV with normal cytology and to assess if co-testing can identify women at high risk of cervical cancer or cervical intraepithelial neoplasia grade 3 (CIN3) or worse over 5 years. METHODS We assessed the 5-year cumulative incidence, starting in 2003-05, of cervical cancer and CIN3 or worse for 331,818 women aged 30 years and older who enrolled in co-testing at Kaiser Permanente Northern California (Berkeley, CA, USA) and had adequate enrolment co-test results. Follow-up continued until Dec 31, 2009. We defined cumulative incidence to include prevalence at enrolment and incidence after enrolment. Prevalence at enrolment was defined as the ratio of women diagnosed with each outcome on the biopsy visit immediately after their enrolment screening visit to the total enrolled women. At screening visits only HPV test and Pap smear samples were collected, and at biopsy visits colposcopically directed biopsies were taken. To estimate post-enrolment incidence, we used Weibull survival models. FINDINGS In 315,061 women negative by HPV testing, the 5-year cumulative incidence of cancer was 3.8 per 100,000 women per year, slightly higher than for the 306,969 who were both negative by HPV and Pap testing (3.2 per 100,000), and half the cancer risk of the 319,177 who were negative by Pap testing (7.5 per 100,000). 313,465 (99.5%) women negative by HPV testing had either normal cytology or equivocal abnormalities. Abnormal cytology greatly increased cumulative incidence of CIN3 or worse over 5 years for the 16,757 positive by HPV testing (12.1%vs 5.9%; p<0.0001). By contrast, although statistically significant, abnormal cytology did not increase 5-year risk of CIN3 or worse for women negative by HPV testing to a substantial level (0.86%vs 0.16%; p=0.004). 12,208 (73%) of the women positive by HPV testing had no cytological abnormality, and these women had 258 (35%) of 747 CIN3 or adenocarcinoma in situ, [corrected] 25 (29%) of 87 cancers, and 17 (63%) of 27 adenocarcinomas. INTERPRETATION For women aged 30 years and older in routine clinical practice who are negative by co-testing (both HPV and cytology), 3-year screening intervals were safe because a single negative test for HPV was sufficient to reassure against cervical cancer over 5 years. Incorporating HPV testing with cytology also resulted in earlier identification of women at high risk of cervical cancer, especially adenocarcinoma. Testing for HPV without adjunctive cytology might be sufficiently sensitive for primary screening for cervical cancer. FUNDING Intramural Research Program of the US National Cancer Institute/NIH/DHHS, and the American Cancer Society.

Longitudinal Study of Human Papillomavirus Persistence and Cervical Intraepithelial Neoplasia Grade 2/3: Critical Role of Duration of Infection

BACKGROUND The natural history of human papillomavirus (HPV) infections in older women is critical for preventive strategies, including vaccination and screening intervals, but is poorly understood. In a 7-year population-based cohort study in Guanacaste, Costa Rica, we examined whether womens age and the duration of carcinogenic HPV infections influenced subsequent persistence of infection and risk of cervical intraepithelial neoplasia grade 2 (CIN 2) or worse disease. METHODS At enrollment, of the 9466 participants eligible for pelvic examination, 9175 were screened for cervical neoplasia using multiple methods; those with CIN 2 or worse disease were censored and treated. Participants at low risk of CIN 2 or worse (n = 6029) were rescreened at 5-7 years (passively followed), whereas higher-risk participants (n = 2115) and subsets of low-risk women (n = 540) and initially sexually inactive women (n = 410) were rescreened annually or semiannually (actively followed) for up to 7 years. HPV testing was done using a polymerase chain reaction-based method. We determined, by four age groups (18-25, 26-33, 34-41, and > or =42 years), the proportion of prevalent infections (found at baseline) and newly detected infections (first found during follow-up) that persisted at successive 1-year time points and calculated absolute risks of CIN 2 and CIN grade 3 (CIN 3) or worse during follow-up. P values are two-sided. RESULTS Regardless of the womans age, newly detected infections were associated with very low absolute risks of persistence, CIN 2, or worse disease. For newly detected infections, the rate of progression to CIN 2+ (or CIN 3+), after 3 years of follow-up, was not higher for women aged 34 years and older than for younger women. Moreover, rates of newly detected infections declined sharply with age (in the actively followed group, at ages 18-25, 26-33, 34-41, and > or =42 years, rates were 35.9%, 30.6%, 18.1%, and 13.5%, respectively; P < .001). Among prevalent infections, persistent infections among older women (> or =42 years) was higher than that among younger age groups or new infections at any age (P < .01 for comparison of eight groups). Most (66 of 85) CIN 2 or worse detected during follow-up was associated with prevalent infections. Only a small subset (25 of 1128) of prevalent infections persisted throughout follow-up without apparent CIN 2 or worse. CONCLUSIONS The rate of new infections declines with age, and new infections typically do not progress to CIN 2 or worse disease in older women; thus, overall potential benefit of prophylactic vaccination or frequent HPV screening to prevent or detect new carcinogenic HPV infections at older ages is low.

Risk of cataract after exposure to low doses of ionizing radiation: a 20-year prospective cohort study among US radiologic technologists.

The study aim was to determine the risk of cataract among radiologic technologists with respect to occupational and nonoccupational exposures to ionizing radiation and to personal characteristics. A prospective cohort of 35,705 cataract-free US radiologic technologists aged 24-44 years was followed for nearly 20 years (1983-2004) by using two follow-up questionnaires. During the study period, 2,382 cataracts and 647 cataract extractions were reported. Cigarette smoking for >or=5 pack-years; body mass index of >or=25 kg/m(2); and history of diabetes, hypertension, hypercholesterolemia, or arthritis at baseline were significantly (p <or= 0.05) associated with increased risk of cataract. In multivariate models, self-report of >or=3 x-rays to the face/neck was associated with a hazard ratio of cataract of 1.25 (95% confidence interval: 1.06, 1.47). For workers in the highest category (mean, 60 mGy) versus lowest category (mean, 5 mGy) of occupational dose to the lens of the eye, the adjusted hazard ratio of cataract was 1.18 (95% confidence interval: 0.99, 1.40). Findings challenge the National Council on Radiation Protection and International Commission on Radiological Protection assumptions that the lowest cumulative ionizing radiation dose to the lens of the eye that can produce a progressive cataract is approximately 2 Gy, and they support the hypothesis that the lowest cataractogenic dose in humans is substantially less than previously thought.

Benchmarking CIN 3+ risk as the basis for incorporating HPV and Pap cotesting into cervical screening and management guidelines.

Objective In 2012, the US Preventive Services Task Force (USPSTF) and a consensus of 25 organizations endorsed concurrent cytology and human papillomavirus (HPV) testing (“cotesting”) for cervical cancer screening. Past screening and management guidelines were implicitly based on risks defined by Pap-alone, without consideration of HPV test results. To promote management that is consistent with accepted practice, new guidelines incorporating cotesting should aim to achieve equal management of women at equal risk of cervical intraepithelial neoplasia grade 3 and cancer (CIN 3+). Methods We estimated cumulative 5-year risks of CIN 3+ for 965,360 women aged 30 to 64 years undergoing cotesting at Kaiser Permanente Northern California over 2003 to 2010. We calculated the implicit risk thresholds for Pap-alone and applied them for new management guidance on HPV and Pap cotesting, citing 2 examples: HPV-positive/atypical squamous cells of undetermined significance (ASC-US) and HPV-negative/Pap-negative. We call this guidance process “benchmarking.” Results A low-grade squamous intraepithelial lesion result, for which immediate colposcopy is prescribed, carries a 5-year CIN 3+ risk of 5.2%, suggesting that test results with similar risks should be managed with colposcopy. Similarly, ASC-US (2.6% risk) is managed with a 6- to 12-month follow-up visit and Pap-negative (0.26% risk) is managed with a 3-year follow-up visit. The 5-year CIN 3+ risk among women with HPV-positive/ASC-US was 6.8% (95% confidence interval = 6.2%–7.6%). This is greater than the 5.2% risk implicitly leading to referral for colposcopy, consistent with current management recommendations that women with HPV-positive/ASC-US be referred for immediate colposcopy. The 5-year CIN 3+ risk among women with HPV-negative/Pap-negative results was 0.08% (95% confidence interval = 0.07%–0.09%), far below the 0.26% implicitly required for a 3-year return and justifying a longer (e.g., 5-year) return. Conclusions Using the principle of “equal management of equal risks,” benchmarking to implicit risk thresholds based on Pap-alone can be used to achieve safe and consistent incorporation of cotesting.

Five-year risks of CIN 3+ and cervical cancer among women who test Pap-negative but are HPV-positive.

Objective Current US guidelines for cotesting recommend that the large numbers of women who test Pap-negative, but human papillomavirus (HPV)–positive, return in 1 year, and those who remain HPV-positive or have low-grade squamous intraepithelial lesion (LSIL) or worse Pap results be referred for colposcopy. However, the performance of these guidelines in routine clinical practice has not been evaluated. Methods We estimated cumulative 5-year risks of cervical intraepithelial neoplasia grade 3 or worse (CIN 3+) among 32,374 women aged 30 to 64 years with HPV-positive/Pap-negative cotest results at Kaiser Permanente Northern California during 2003 to 2010. Results The 5-year CIN 3+ risk after an HPV-positive/Pap-negative cotest result, which was found in 3.6% of women, was 4.5% (95% confidence interval [CI] = 4.2%–4.8%). The 5-year cancer risk was 0.34% (95% CI = 0.26%–0.45%), and half of the cases were adenocarcinoma. Overall, 48% of the women remained HPV-positive on return (median = 418 days after baseline), a percentage that varied little over ages 30 to 64 years. At the return after a baseline HPV-positive/Pap-negative result, almost every repeat cotest result predicted greater subsequent 5-year CIN 3+ risk than the same cotest result had at baseline (HPV-positive/LSIL, 9.2% vs 6.1%, p = .01; HPV-positive/atypical squamous cells of undetermined significance [ASC-US], 7.9% vs 6.8%, p = .2; HPV-positive/Pap-negative, 7.4% vs 4.5%, p < .0001; HPV-negative/LSIL,1.7% vs 2.0%, p = .8; HPV-negative/ASC-US, 2.9% vs 0.43%, p = .0005; HPV-negative/Pap-negative, 0.93% vs 0.08%, p < .0001). Conclusions Using the principle of “equal management of equal risks,” women testing HPV-positive/Pap-negative had a subsequent CIN 3+ risk consistent with risk thresholds for a 1-year return. However, on returning in approximately 1 year, about one-half of women will be referred for colposcopy because of continued HPV positivity or Pap abnormality. Clinicians should keep in mind that cotest results at the return after a baseline HPV-positive/Pap-negative finding are riskier than the same baseline cotest results in the general population, supporting intensified clinical management at return testing.

Five-year risks of CIN 3+ and cervical cancer among women with HPV testing of ASC-US Pap results.

Objective New screening guidelines recommend that human papillomavirus (HPV)–negative/atypical squamous cells of undetermined significance (ASC-US) results be considered as equivalent to HPV-negative/Pap-negative results, leading to rescreening in 5 years. However, despite ample data, the routine clinical performance of HPV testing of women with ASC-US has not been adequately documented. Methods We estimated 5-year risks of cervical intraepithelial neoplasia (CIN) 3+ and of cancer among 2 groups of women between 2003 and 2010 at Kaiser Permanente Northern California: 27,050 aged 30 to 64 years who underwent HPV and Pap cotesting and had an ASC-US Pap result and 12,209 aged 25 to 29 years who underwent HPV triage of ASC-US. Results Five-year risks of CIN 3+ and of cancer among women aged 30 to 64 years testing HPV-negative/ASC-US and among 923,152 women testing Pap-negative alone were similar although statistically distinguishable (CIN 3+, 0.43% vs 0.26%, p = .001; cancer, 0.050% vs 0.025%, p = .1). The increased risk of cancer after HPV-negative/ASC-US versus Pap-negative alone was confined to women aged 60 to 64 years (0.26% vs 0.035%, p = .3). Five-year risks of CIN 3+ and cancer among women with HPV-negative/ASC-US results were substantially higher than those among women testing HPV-negative/Pap-negative (CIN 3+, 0.43% vs 0.08%, p < .0001; cancer, 0.050% vs 0.011%, p = .003). For women aged 30 to 64 years testing HPV-positive/ASC-US, 5-year risks of CIN 3+ and cancer were slightly higher than those among 9,374 women with low-grade squamous intraepithelial lesion (LSIL) (CIN 3+, 6.8% vs 5.2%, p = .0007; cancer, 0.41% vs 0.16%, p = .04). Similar patterns were seen for women aged 25 to 29 years. Conclusions Women with HPV-negative/ASC-US had a similar risk as women testing Pap-negative alone but had a higher risk than women testing HPV-negative/Pap-negative. Based upon the principle of “equal management of equal risks,” our findings support the equal management of women with HPV-negative/ASC-US and those with Pap-negative alone, except for exiting women from screening because cancer risks at ages 60 to 64 years may be higher for women testing HPV-negative/ASC-US. Our findings also support managing HPV-positive/ASC-US and LSIL similarly.

Development and Validation of Risk Models to Select Ever-Smokers for CT Lung Cancer Screening

IMPORTANCE The US Preventive Services Task Force (USPSTF) recommends computed tomography (CT) lung cancer screening for ever-smokers aged 55 to 80 years who have smoked at least 30 pack-years with no more than 15 years since quitting. However, selecting ever-smokers for screening using individualized lung cancer risk calculations may be more effective and efficient than current USPSTF recommendations. OBJECTIVE Comparison of modeled outcomes from risk-based CT lung-screening strategies vs USPSTF recommendations. DESIGN, SETTING, AND PARTICIPANTS Empirical risk models for lung cancer incidence and death in the absence of CT screening using data on ever-smokers from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO; 1993-2009) control group. Covariates included age; education; sex; race; smoking intensity, duration, and quit-years; body mass index; family history of lung cancer; and self-reported emphysema. Model validation in the chest radiography groups of the PLCO and the National Lung Screening Trial (NLST; 2002-2009), with additional validation of the death model in the National Health Interview Survey (NHIS; 1997-2001), a representative sample of the United States. Models were applied to US ever-smokers aged 50 to 80 years (NHIS 2010-2012) to estimate outcomes of risk-based selection for CT lung screening, assuming screening for all ever-smokers, yield the percent changes in lung cancer detection and death observed in the NLST. EXPOSURES Annual CT lung screening for 3 years beginning at age 50 years. MAIN OUTCOMES AND MEASURES For model validity: calibration (number of model-predicted cases divided by number of observed cases [estimated/observed]) and discrimination (area under curve [AUC]). For modeled screening outcomes: estimated number of screen-avertable lung cancer deaths and estimated screening effectiveness (number needed to screen [NNS] to prevent 1 lung cancer death). RESULTS Lung cancer incidence and death risk models were well calibrated in PLCO and NLST. The lung cancer death model calibrated and discriminated well for US ever-smokers aged 50 to 80 years (NHIS 1997-2001: estimated/observed = 0.94 [95%CI, 0.84-1.05]; AUC, 0.78 [95%CI, 0.76-0.80]). Under USPSTF recommendations, the models estimated 9.0 million US ever-smokers would qualify for lung cancer screening and 46,488 (95% CI, 43,924-49,053) lung cancer deaths were estimated as screen-avertable over 5 years (estimated NNS, 194 [95% CI, 187-201]). In contrast, risk-based selection screening of the same number of ever-smokers (9.0 million) at highest 5-year lung cancer risk (≥1.9%) was estimated to avert 20% more deaths (55,717 [95% CI, 53,033-58,400]) and was estimated to reduce the estimated NNS by 17% (NNS, 162 [95% CI, 157-166]). CONCLUSIONS AND RELEVANCE Among a cohort of US ever-smokers aged 50 to 80 years, application of a risk-based model for CT screening for lung cancer compared with a model based on USPSTF recommendations was estimated to be associated with a greater number of lung cancer deaths prevented over 5 years, along with a lower NNS to prevent 1 lung cancer death.

Five-year risk of recurrence after treatment of CIN 2, CIN 3, or AIS: performance of HPV and Pap cotesting in posttreatment management.

Objective After excisional treatment, cervical intraepithelial neoplasia grade 2 or worse (CIN 2+) can recur. It is not clear how many negative posttreatment Pap or cotest results are needed to ensure adequate safety against CIN 2+ before returning to extended retesting intervals. Methods We observed 5-year risks of CIN 2+ for 3 follow-up management strategies after treatment (Pap-alone, human papillomavirus [HPV]-alone, and HPV/Pap cotesting) for 3,273 women aged 25 years and older who were treated for CIN 2, CIN 3, or adenocarcinoma in situ (AIS) between 2003 and 2010 at Kaiser Permanente Northern California. Results Five-year risks of recurrent CIN 2+ after treatment varied both by antecedent screening test result and the histology of the treated lesion. The risk ranged from 5% for CIN 2 preceded by HPV-positive/atypical squamous cells of undetermined significance or low-grade squamous intraepithelial lesion to 16% for CIN 3/AIS preceded by atypical glandular cells (AGC)/atypical squamous cells cannot rule out high-grade squamous intraepithelial lesion (ASC-H)/high-grade squamous intraepithelial lesion or worse (HSIL+) (p < .0001). However, after posttreatment negative tests, risks were lowered and similar regardless of antecedent screening test and histology of treated disease. The 5-year recurrent CIN 2+ risk after a negative posttreatment cotest (2.4%) was lower than that following a negative HPV test (3.7%, p = .3) or negative Pap result (4.2%, p = .1). Two negative posttreatment tests of each kind conferred slightly lower 5-year CIN 2+ risk than one (2 negative Pap tests vs. 1, 2.7% vs 4.2%, p = .2; 2 negative HPV tests vs. 1, 2.7% vs 3.7%, p = .7; 2 negative cotests vs. 1, 1.5% vs 2.4%, p = .8). The 5-year CIN 2+ risk after 2 negative cotests of 1.5% (95% confidence interval = 0.3%–7.2%) approached the 0.68% risk after a negative Pap test during routine screening. Conclusions Women with antecedent AGC/ASC-H/HSIL+ Pap results or those treated for CIN 3/AIS had a substantial risk of developing CIN 2+ posttreatment. On the basis of the principle of “equal management of equal risks,” after negative test results posttreatment, no subgroup of women achieved risk sufficiently low to return to 5-year routine screening. However, negative cotests after treatment provided more reassurance against recurrent CIN 2+ than either negative Pap tests or HPV tests alone.

Follow-up testing after colposcopy: five-year risk of CIN 2+ after a colposcopic diagnosis of CIN 1 or less.

Objective Most women referred for colposcopy are not diagnosed with cervical intraepithelial neoplasia grade 2 or worse (CIN 2+) but, nonetheless, are typically asked to return much sooner than their next routine screening interval in 3 to 5 years. An important question is how many subsequent negative Pap results, or negative Pap and human papillomavirus (HPV) cotest results, are needed before returning to an extended retesting interval. Methods We estimated 5-year risks of CIN 2+ for 3 follow-up management strategies after colposcopy (Pap-alone, HPV-alone, and cotesting) for 20,319 women aged 25 years and older screened from 2003 to 2010 at Kaiser Permanente Northern California who were referred for colposcopy but for whom CIN 2+ was not initially diagnosed (i.e., “women with CIN 1/negative colposcopy”). Results Screening results immediately antecedent to CIN 1/negative colposcopy influenced subsequent 5-year CIN 2+ risk: women with an antecedent HPV-positive/atypical squamous cells of undetermined significance (ASCUS) or low-grade squamous intraepithelial lesion (LSIL) Pap had a lower risk (10%) than those with antecedent atypical squamous cells cannot rule out HSIL (ASC-H; 16%, p < .0001) or high-grade squamous intraepithelial lesion or worse (HSIL+; 24%, p < .0001). For women with an antecedent HPV-positive/ASC-US or LSIL, a single negative cotest approximately 1 year after colposcopy predicted lower subsequent 5-year risk of CIN 2+ (1.1%) than 2 sequential negative HPV tests (1.8%, p = .3) or 2 sequential negative Pap results (4.0%, p < .0001). For those with an antecedent ASC-H or HSIL+ Pap, 1 negative cotest 1 year after colposcopy predicted lower subsequent 5-year risk of CIN 2+ (2.2%) than 1 negative HPV test (4.4%, p = .4) or 1 negative Pap (7.0%, p = .06); insufficient data existed to calculate the risk after sequential negative cotests for women with high-grade antecedent cytology. Conclusions Women with a CIN 1/negative colposcopy followed by negative postcolposcopy tests did not achieve sufficiently low CIN 2+ risk to return to 5-year routine screening. For women with antecedent HPV-positive/ASC-US or LSIL, a single negative postcolposcopy cotest reduced their risk to a level consistent with a 3-year return. For women with antecedent ASC-H or HSIL+, no single negative test result sufficed to reduce their risk to a level consistent with a 3-year return.

Five-year risks of CIN 3+ and cervical cancer among women with HPV-positive and HPV-negative high-grade pap results

Objective High-grade Pap results (e.g., atypical glandular cells [AGC], atypical squamous cells cannot rule out HSIL [ASC-H], and high-grade squamous intraepithelial lesion [HSIL]) predict high cancer risks, resulting in referral for colposcopy without HPV triage. However, new guidelines recommending cotesting for women 30 years and older imply that clinicians will often receive the HPV test result concurrently for high-grade Pap results. We examined whether HPV testing provides useful risk stratification in this context. Methods From a cohort of 965,360 women aged 30 to 64 years undergoing cotesting at Kaiser Permanente Northern California, we estimated 5-year risks for cervical cancer and CIN 3+ after AGC (2,074 women), ASC-H (1,647 women), and HSIL (2,019 women) according to HPV test results. Results HPV positivity of AGC Pap results was 25% and decreased with age (30 to 34 vs 60 to 64 years, 44% vs 17%, p < .0001), whereas HPV positivity of ASC-H and HSIL was much higher (71% and 94%) and decreased less with age. Even for these high-grade Pap results, 5-year CIN 3+ risks differed substantially between HPV-positive and HPV-negative women (AGC, 33% vs 0.93%, p < .0001; ASC-H, 25% vs 3.5%, p < .0001; HSIL, 49% vs 30%, p = .006). However, except for AGC, cervical cancer risks differed less between HPV-positive and HPV-negative women (AGC, 9.0% vs 0.37%, p < .0001; ASC-H, 2.5% vs 2.1%, p = .8; HSIL, 6.6% vs 6.8%, p = .7). Conclusions The risks of CIN 3+ among women with HPV-negative high-grade Pap results were lower than those among women with HPV-positive high-grade Pap results, especially after AGC. However, by the principle of “equal management of equal risks,” all HPV-negative high-grade Pap results had cancer risks high enough to warrant colposcopy, confirming that there is no current role for HPV triage of high-grade Pap results.