Assessing global transitions in human development and colorectal cancer incidence

Colorectal cancer incidence has paralleled increases in human development across most countries. Yet, marked decreases in incidence are now observed in countries that have attained very high human development. Thus, in this study, we explored the relationship between human development and colorectal cancer incidence, and in particular assessed whether national transitions to very high human development are linked to temporal patterns in colorectal cancer incidence. For these analyses, we utilized the Human Development Index (HDI) and annual incidence data from regional and national cancer registries. Truncated (30-74 years) age-standardized incidence rates were calculated. Yearly incidence rate ratios and HDI ratios, before and after transitioning to very high human development, were also estimated. Among the 29 countries investigated, colorectal cancer incidence was observed to decrease after reaching the very high human development threshold for 12 countries; decreases were also observed in a further five countries, but the age-standardized incidence rates remained higher than that observed at the threshold. Such declines or stabilizations are likely due to colorectal cancer screening in some populations, as well as varying levels of exposure to protective factors. In summary, it appears that there is a threshold at which human development predicts a stabilization or decline in colorectal cancer incidence, though this pattern was not observed for all countries assessed. Future cancer planning must consider the increasing colorectal cancer burden expected in countries transitioning towards higher levels of human development, as well as possible declines in incidence among countries reaching the highest development level.

Immuno-related polymorphisms and cervical cancer risk: The IARC multicentric case-control study

A small proportion of women who are exposed to infection with human-papillomavirus (HPV) develop cervical cancer (CC). Genetic factors may affect the risk of progression from HPV infection to cervical precancer and cancer. We used samples from the International Agency for Research on Cancer (IARC) multicentric case-control study to evaluate the association of selected genetic variants with CC. Overall, 790 CC cases and 717 controls from Algeria, Morocco, India and Thailand were included. Cervical exfoliated cells were obtained from control women and cervical exfoliated cells or biopsy specimens from cases. HPV-positivity was determined using a general primer GP5+/6+ mediated PCR. Unconditional logistic regression was used to estimate odds ratios (OR) and corresponding 95% confidence intervals (CI) of host genotypes with CC risk, using the homozygous wild type genotype as the referent category and adjusting by age and study centre. The association of polymorphisms with the risk of high-risk HPV-positivity among controls was also evaluated. A statistically significant association was observed between single nucleotide polymorphism (SNP) CHR6 rs2844511 and CC risk: the OR for carriers of the GA or GG genotypes was 0.70 (95% CI: 0.43-1.14) and 0.61 (95% CI: 0.38-0.98), respectively, relative to carriers of AA genotype (p-value for trend 0.03). We also observed associations of borderline significance with the TIPARP rs2665390 polymorphism, which was previously found to be associated with ovarian and breast cancer, and with the EXOC1 rs13117307 polymorphism, which has been linked to cervical cancer in a large study in a Chinese population. We confirmed the association between CC and the rs2844511 polymorphism previously identified in a GWAS study in a Swedish population. The major histocompatibility region of chromosome 6, or perhaps other SNPs in linkage disequilibrium, may be involved in CC onset.

Preventable fractions of cervical cancer via effective screening in six Baltic, central, and eastern European countries 2017-40: a population-based study

BACKGROUND

Cervical cancer incidence remains high in several Baltic, central, and eastern European (BCEE) countries, mainly as a result of a historical absence of effective screening programmes. As a catalyst for action, we aimed to estimate the number of women who could be spared from cervical cancer across six countries in the region during the next 25 years, if effective screening interventions were introduced.

METHODS

In this population-based study, we applied age-period-cohort models with spline functions within a Bayesian framework to incidence data from six BCEE countries (Estonia, Latvia, Lithuania, Belarus, Bulgaria, and Russia) to develop projections of the future number of new cases of cervical cancer from 2017 to 2040 based on two future scenarios: continued absence of screening (scenario A) versus the introduction of effective screening from 2017 onwards (scenario B). The timespan of available data varied from 16 years in Bulgaria to 40 years in Estonia. Projected rates up to 2040 were obtained in scenario A by extrapolating cohort-specific trends, a marker of changing risk of human papillomavirus (HPV) infection, assuming a continued absence of effective screening in future years. Scenario B added the effect of gradual introduction of screening in each country, under the assumption period effects would be equivalent to the decreasing trend by calendar year seen in Denmark (our comparator country) since the progressive regional introduction of screening from the late 1960s.

FINDINGS

According to scenario A, projected incidence rates will continue to increase substantially in many BCEE countries. Very high age-standardised rates of cervical cancer are predicted in Lithuania, Latvia, Belarus, and Estonia (up to 88 cases per 100 000). According to scenario B, the beneficial effects of effective screening will increase progressively over time, leading to a 50-60% reduction of the projected incidence rates by around 2040, resulting in the prevention of cervical cancer in 1500 women in Estonia and more than 150 000 women in Russia. The immediate launch of effective screening programmes could prevent almost 180 000 new cervical cancer diagnoses in a 25-year period in the six BCEE countries studied.

INTERPRETATION

Based on our findings, there is a clear need to begin cervical screening in these six countries as soon as possible to reduce the high and increasing incidence of cervical cancer over the next decades.

FUNDING

None.

Comparison of Two Widely Used Human Papillomavirus Detection and Genotyping Methods, GP5+/6+-Based PCR Followed by Reverse Line Blot Hybridization and Multiplex Type-Specific E7-Based PCR

GP5+/6+-based PCR followed by reverse line blot hybridization (GP5+/6+RLB) and multiplex type-specific PCR (E7-MPG) are two human papillomavirus (HPV) genotyping methodologies widely applied in epidemiological research. We investigated their relative analytical performance in 4,662 samples derived from five studies in Bhutan, Rwanda, and Mongolia coordinated by the International Agency for Research on Cancer (IARC). A total of 630 samples were positive by E7-MPG only (13.5%), 24 were positive by GP5+/6+RLB only (0.5%), and 1,014 were positive (21.8%) by both methods. Ratios of HPV type-specific positivity of the two tests (E7-MPG:GP5+/6+RLB ratio) were calculated among 1,668 samples that were HPV positive by one or both tests. E7-MPG:GP5+/6+RLB ratios were >1 for all types and highly reproducible across populations and sample types. E7-MPG:GP5+/6+RLB ratios were highest for HPV53 (7.5) and HPV68 (7.1). HPV16 (1.6) and HPV18 (1.7) had lower than average E7-MPG:GP5+/6+RLB ratios. Among E7-MPG positive infections, median mean fluorescence intensity (MFI; a semiquantitative measure of viral load) tended to be higher among samples positive for the same virus type by GP5+/6+RLB than for those negative for the same type by GP5+/6+RLB. Exceptions, however, included HPV53, -59, and -82, for which the chances of being undetected by GP5+/6+RLB appeared to be MFI independent. Furthermore, the probability of detecting an additional type by E7-MPG was higher when another type was already detected by GP5+/6+RLB, suggesting the existence of masking effects due to competition for GP5+/6+ PCR primers. In conclusion, this analysis is not an evaluation of clinical performance but may inform choices for HPV genotyping methods in epidemiological studies, when the relative merits and dangers of sensitivity versus specificity for individual types should be considered, as well as the potential to unmask nonvaccine types following HPV vaccination.

Beral's 1974 paper: A step towards universal prevention of cervical cancer

In 1974, Valerie Beral published a landmark paper on the sexually transmitted origin of cervical cancer (CC) using statistics routinely available in the United Kingdom (UK). Among women born between 1902 and 1947, CC mortality rates correlated remarkably well with the incidence rates of gonorrhoea when they were 20 years old and both were highest among women born after 1940. Hence, if CC prevention and treatment had remained unchanged, the youngest generations of women would have experienced a high risk of CC death as they grew older. Fortunately, progress in CC prevention has helped avoid this scenario. The adverse consequences of the "sexual revolution" were greatly mitigated in the UK and other high-resource countries by the implementation of high quality cytology-based CC screening. An age-period-cohort analysis suggests that >30,000 cases or approximately 35% of expected CC cases may have been prevented by screening programmes in the UK between 1983 and 2007 and this percentage has been steadily increasing. In addition, the discovery of the causal role of HPV is reshaping primary and secondary prevention of CC. Cheaper HPV tests are becoming available and HPV-based primary screening may at last facilitate CC screening in low-resource countries. In the long-term, however, HPV vaccination, which has already been adopted by many countries, represents the best hope for preventing CC and overcoming socio-economic differences in CC risk within and across countries. The additional elucidation of HPV cofactors to which Beral has greatly contributed may also help control HPV infection in unvaccinated women.

The Impact of Diagnostic Changes on the Rise in Thyroid Cancer Incidence: A Population-Based Study in Selected High-Resource Countries

BACKGROUND

Thyroid cancer (TC) incidence is rising in many countries, but the corresponding mortality is constant or declining. Incidence increases appear largely restricted to small papillary TC in young/middle-age individuals. We compared age-specific incidence rates across countries and time periods in order to estimate the fraction of TC possibly attributable to increased surveillance of the thyroid gland (diagnostic changes) following the introduction of neck ultrasonography in the 1980s.

METHODS

We focused on high-resource countries, including four Nordic countries, England and Scotland, France, Italy, the United States, Australia, Japan, and the Republic of Korea. Before the 1970s, TC incidence in Nordic countries increased proportionally to the second power of age, consistent with the multistage model of carcinogenesis. Using this historical observation for reference, we attributed the progressive departure from linearity of the age curves in each country to an increased detection of asymptomatic disease in young/middle-age individuals. The proportion of cases attributable to diagnostic changes was estimated from the difference between observed rates and those expected using the Nordic countries as reference.

RESULTS

Diagnostic changes may account for ≥60% of TC cases diagnosed in 2003-2007 in women aged under 80 years in France, Italy, the United States, Australia, and the Republic of Korea, and approximately 50% in other assessed countries, except Japan (30%). The proportions attributable to diagnostic changes were higher in countries with largest incidence increases and were consistent across sexes, although increases were smaller and delayed in men.

CONCLUSIONS

A large proportion of TC cases diagnosed in high-resource countries in the last two decades are likely to be due to diagnostic changes. This proportion has progressively increased over time, and it is likely to grow further in the future. Since there is evidence of harm but no proof of benefit from the intense scrutiny of the thyroid, the dangers of overdiagnosis and overtreatment of TC should be urgently addressed.

50 years of screening in the Nordic countries: quantifying the effects on cervical cancer incidence

BACKGROUND

Nordic countries' data offer a unique possibility to evaluate the long-term benefit of cervical cancer screening in a context of increasing risk of human papillomavirus infection.

METHODS

Ad hoc-refined age-period-cohort models were applied to the last 50-year incidence data from Denmark, Finland, Norway and Sweden to project expected cervical cancer cases in a no-screening scenario.

RESULTS

In the absence of screening, projected incidence rates for 2006-2010 in Nordic countries would have been between 3 and 5 times higher than observed rates. Over 60,000 cases or between 41 and 49% of the expected cases of cervical cancer may have been prevented by the introduction of screening in the late 1960s and early 1970s.

CONCLUSIONS

Our study suggests that screening programmes might have prevented a HPV-driven epidemic of cervical cancer in Nordic countries. According to extrapolations from cohort effects, cervical cancer incidence rates in the Nordic countries would have been otherwise comparable to the highest incidence rates currently detected in low-income countries.

Clustering patterns of human papillomavirus infections among HIV-positive women in Kenya

Background

HIV-positive women are at increased risk of human papillomavirus (HPV) infection, and, especially, multiple infections compared to HIV-negative women. Whether certain HPV types have a tendency to cluster in multiple infections beyond or below what would be expected by shared risk factors (e.g., sexual behavior and the degree of immunosuppression) is unclear. We, therefore, investigated clustering patterns of 44 HPV types in HIV-positive women from Kenya.

Findings

HPV status was assessed on cervical scrapings from 498 women using GP5+/6+ PCR and reverse line blot. Logistic regression was used to model type-specific HPV positivity, adjusted for age, specific HPV type prevalence, CD4, combination antiretroviral therapy, and, in the Full Model, individual-level random effects that represent unobservable risk factors common to all HPV types. We found a modest excess of women with co-infections with 2 HPV types (1.12; 95% credible intervals: 1.03-1.21) in the Full Model but no significant associations of individual types. No significant deviations of observed/expected counts were observed for any 2-way combination of HPV types at either the chosen level of significance, p = 0.00005, or at p = 0.01. Findings were substantially similar when women with CIN2/3 were excluded and when they were stratified by use of anti-retroviral therapy or CD4 count.

Conclusions

HPV co-infections occurred at random in the cervix of HIV-positive women as previously found in HIV-negative women. The removal of HPV types through vaccination should not result, therefore, in an increase or decrease in the prevalence of HPV types not targeted by vaccination in immunosuppressed women.

Patterns of human papillomavirus types in multiple infections: an analysis in women and men of the high throughput human papillomavirus monitoring study

Background

To evaluate the pattern of co-infection of human papillomavirus (HPV) types in both sexes in Sweden.

Methods

Cell samples from genital swabs, first-void urine, and genital swabs immersed in first-void urine were collected in the present cross-sectional High Throughput HPV Monitoring study. Overall, 31,717 samples from women and 9,949 from men (mean age 25) were tested for 16 HPV types using mass spectrometry. Multilevel logistic regression was used to estimate the expected number of multiple infections with specific HPV types, adjusted for age, type of sample, and accounting for correlations between HPV types due to unobserved risk factors using sample-level random effects. Bonferroni correction was used to allow for multiple comparisons (120).

Results

Observed-to-expected ratio for any multiple infections was slightly above unity in both sexes, but, for most 2-type combinations, there was no evidence of significant departure from expected numbers. HPV6/18 was found more often and HPV51/68 and 6/68 less often than expected. However, HPV68 tended to be generally underrepresented in co-infections, suggesting a sub-optimal performance of our testing method for this HPV type.

Conclusions

We found no evidence for positive or negative clustering between HPV types included in the current prophylactic vaccines and other untargeted oncogenic types, in either sex.

Worldwide trends in cervical cancer incidence: impact of screening against changes in disease risk factors

BACKGROUND

Cervical cancer trends in a given country mainly depend on the existence of effective screening programmes and time changes in disease risk factors, notably exposure to human papillomavirus (HPV). Screening primarily influences variations by period of diagnosis, whereas changes in risk factors chiefly manifest themselves as variations in risk across successive birth cohorts of women.

METHODS

We assessed trends in cervical cancer across 38 countries in five continents, age group 30-74 years, using age-standardised incidence rates (ASRs) and age-period-cohort (APC) models. Non-identifiability in APC models was circumvented by making assumptions based on a consistent relationship between age and cervical cancer incidence (i.e. approximately constant rates after age 45 years).

FINDINGS

ASRs decreased in several countries, except in most of Eastern European populations, Thailand as well as Uganda, although the direction and magnitude of period and birth cohort effects varied substantially. Strong downward trends in cervical cancer risk by period were found in the highest-income countries, whereas no clear changes by period were found in lower-resourced settings. Successive generations of women born after 1940 or 1950 exhibited either an increase in risk of cervical cancer (in most European countries, Japan, China), no substantial changes (North America and Australia) or a decrease (Ecuador and India).

INTERPRETATION

In countries where effective screening has been in place for a long time the consequences of underlying increases in cohort-specific risk were largely avoided. In the absence of screening, cohort-led increases or, stable, cervical cancer ASRs were observed. Our study underscores the importance of strengthening screening efforts and augmenting existing cancer control efforts with HPV vaccination, notably in those countries where unfavourable cohort effects are continuing or emerging.

FUNDING

Bill and Melinda Gates Foundation (BMGF).

KRAS aKtive, an Italian network for assessment of KRAS mutations in colorectal cancer patients: Results on 7,432 cases

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Background: The KRAS aKtive program was started on March 2009, promoted by the Italian Association of Medical Oncology (AIOM) and the Italian Society of Surgical Pathology and Cytopathologyy (SIAPEC) to support the activity of oncologists and pathologists involved in the management of metastatic colorectal cancer patients who need the assessment of the mutational status of the KRAS gene. Methods: The program was specifically devised to facilitate the exchange of biologic material, clinicopathological data and diagnostic reports within a network of oncologist, pathologists and pathology/molecular biology reference laboratories throughout Italy, connected through the site www.kras-aKtive.it. KRAS mutation analysis was performed by Sanger sequencing (SS), real time PCR or other techniques, including pyrosequencing and hybridization strip assays. Data were collected in a common database. Results: The KRAS aKtive program has involved 478 oncologists, 144 pathologists, and 24 reference laboratories. A total of 7,432 KRAS mutations analyses were performed. The tests were informative in 7,265 cases (98%). The vast majority of tests (5,626 cases, 77.4%) were conducted by SS. In 529 (7.3%) cases a real-time PCR assay was used, other detection techniques were used in 1,110 (15.3%) cases. KRAS mutations at codons 12-13 were detected in 2,874 cases (39,6%). The frequency of mutations detected by real-time PCR or other techniques (45%, and 43%, respectively) was significantly higher (p=0.002, and p=0.008%, respectively) than that observed by SS (38%). The percentage of cases evaluated by non-SS-based methods has increased during the first three years of the program. Conclusions: The results of this large survey allow an accurate estimation of the actual prevalence of KRAS mutations and their types in caucasian colorectal cancer patients. Our data indicate that the frequency of mutations detected by non-SS-based methods is higher than that obtained by SS.

Dried blood spot samples for seroepidemiology of infections with human papillomaviruses, Helicobacter pylori, Hepatitis C Virus, and JC Virus

BACKGROUND

To establish antibody analysis from dried blood spots (DBS) on filter paper for seroepidemiologic infection and cancer association studies, we analyzed data from a population-based study in Mongolia.

METHODS

Using multiplex serology, we analyzed 985 paired DBS and serum samples from the same donors for antibodies to 12 different proteins from four groups of infectious agents: human papillomaviruses (HPV), Helicobacter pylori (H. pylori), hepatitis C virus (HCV), and JC polyomavirus (JCV).

RESULTS

Quantitative antibody reactivities in serum and DBS showed good correlation, with median correlation coefficients (Pearson R(2)) of 0.88 (range, 0.80-0.90) for high-titer (i.e., H. pylori, HCV, JCV) and 0.79 (range, 0.72-0.85) for low-titer antibodies (i.e., HPV). For high-titer antibodies, serum and DBS data were comparable (median slope of linear trend line, 1.14; range, 1.09-1.21), whereas for low-titer antibodies, DBS reactivities were lower than in serum (median slope, 0.54; range, 0.50-0.80). By extrapolating seropositivity cutoff points previously defined for serum to DBS, we found high agreement (>89% for all antigens) of dichotomized DBS and serum results and median kappa values for high- and low-titer antibodies of 0.86 and 0.78 (range, 0.78-0.92 and 0.55-0.86), respectively. Epidemiologic associations with known risk factors for HPV antibodies were as strong for DBS as for serum.

CONCLUSIONS

DBS provide a reliable alternative to serum or plasma for detection of antibodies against various pathogens by multiplex serology.

IMPACT

DBS do not require blood centrifugation and allow storage and shipment at ambient temperature, thus facilitating field work for seroepidemiologic studies especially in environments with limited technical infrastructure.

Human papillomavirus infection in women with and without cervical cancer in Tbilisi, Georgia

BACKGROUND

No accurate estimates of cervical cancer incidence or mortality currently exist in Georgia. Nor are there any data on the population-based prevalence of high-risk (HR) human papillomavirus (HPV) infection, which, in the absence of good-quality screening, is known to correlate with cervical cancer incidence.

METHODS

We obtained cervical cell specimens from 1309 women aged 18-59 years from the general population of Tbilisi, and also from 91 locally diagnosed invasive cervical cancers (ICC). DNA of 44 HPV types was tested for using a GP5+/6+-based PCR assay.

RESULTS

In the general population (of whom 2% reported a previous Pap smear) HPV prevalence was 13.5% (95% CI: 11.6-15.9), being highest in women aged 25-34 years (18.7%) and falling to between 8.6% and 9.5% for all age groups above 34 years. HR HPV prevalence was 8.6% overall, being 6.8% and 38.9% among women with normal and abnormal cytology, respectively. HPV45 (1.6%) was the most common type in women with normal cytology, whereas HPV16 predominated among women with cervical abnormalities (including 7 of 10 histologically confirmed cervical intraepithelial neoplasia 2/3) and among ICC (57.6%). The next most common types in ICC in Georgia were HPV45 and 18 (13.2 and 11.0%, respectively).

CONCLUSIONS

We report a relatively high burden of HPV infection in Tbilisi, Georgia. Improving cervical cancer prevention, through screening and/or HPV vaccination, is an important public health issue in Georgia, where 70% of ICC are theoretically preventable by HPV16/18 vaccines.

Clustering of human papillomavirus (HPV) types in the male genital tract: the HPV in men (HIM) study

OBJECTIVE

To evaluate clustering patterns of prevalent infection with multiple human papillomavirus (HPV) types in 3677 men from the HPV in Men (HIM) study.

METHODS

HPV testing was performed in samples combined from the glans penis/coronal sulcus, the shaft, and the scrotum by Linear Array methodology. Linear Array uses a mixed probe to assess HPV52 positivity, which limits the assay's ability to determine HPV52 status in the presence of HPV33, 35, or 58. Logistic regression was used to model type-specific HPV positivity, adjusted for age, study area, lifetime number of sexual partners, and specific HPV type prevalence. Participant-level random effects were added to represent unobservable risk factors common to all HPV types.

RESULTS

The observed-to-expected ratio for infections with ≥ 3 types was 1.09 (95% credible interval, 1.04-1.14). For the majority of 2-type combinations, no evidence was found of a significant departure of the observed from the expected number. An apparent clustering of HPV52 with HPV35 or 58 was observed, because of limitation in the ability of Linear Array to define HPV52 positivity.

CONCLUSIONS

Our study showed that, despite obvious anatomical differences, HPV coinfections do seem to occur at random in the male external genitalia as in the female cervix.

Clustering of multiple human papillomavirus infections in women from a population-based study in Guanacaste, Costa Rica

OBJECTIVE

To evaluate clustering patterns of prevalent infection with multiple human papillomavirus (HPV) types in 8365 nonhysterectomized women from the Guanacaste Study of HPV Natural History.

METHODS

HPV testing was performed on cervical cells by MY09/M11 L1 degenerate consensus primer polymerase chain reaction method, with dot-blot hybridization for genotyping. Logistic regression was used to model type-specific HPV positivity, adjusted for age, lifetime number of sexual partners, and specific HPV type prevalence. Woman-level random effects were added to represent unobservable risk factors common to all HPV types.

RESULTS

The observed-to-expected ratio for infections with 2 types was 1.16 (95% credible interval: 1.11-1.21) and for ≥3 types was 1.04 (95% credible interval: .96-1.13). The tendency of HPV types to cluster increased significantly with the genetic similarity of L1 regions. P value < .01 was observed for 2 HPV pairs: HPV-62 and -81 were found together more, while HPV-51 and -71 were found together less often than expected.

CONCLUSIONS

We found a small degree of aggregation between any HPV types and lack of clustering between specific carcinogenic types. Our data indirectly provide reassurance on lack of misclassification for the large majority of HPV types in multiple infections detected by the MY09/11 method and genotyped using dot-blot hybridization.