Monitoring interval cancers in mammographic screening: the Florence District programme experience

The potential of mobile health clinics in chronic disease prevention and health promotion in universal healthcare systems. An on-field experiment

BACKGROUND

Mobile health clinics (MHCs) are recognized to facilitate access to healthcare services, especially in disadvantaged populations. Notwithstanding that in Europe a wide-ranging background in mobile screening units for cancer is shared, evidences about MHCs targeting also at other non-communicable diseases (NCDs) in universal health coverage systems are scarce. The aim of this study was to describe the population attracted with a MHC initiative and to assess the potential of this tool in prevention and control of NCDs.

METHODS

Our MHC was set up in a railway wagon. Standard body measurements, finger-stick glucose, total cholesterol and blood pressure were recorded. Participants were asked about smoking, physical activity, diet, compliance to national cancer screening programmes and ongoing pharmacological treatment. One-to-one counselling was then provided.

RESULTS

Participants (n = 839) showed a higher prevalence of overweight/obesity, insufficient intake of vegetables, sedentary lifestyle, and a lower compliance to cancer screening compared with reference population. Our initiative attracted groups at higher risk, such as foreigners, men and people aged from 50 to 69. The proportion of newly diagnosed or uncontrolled disease exceeded 40% of participants for both hypertension and hypercholesterolemia (7% for diabetes). Adherence rate to counselling was 99.4%.

CONCLUSIONS

The MHC was effective in attracting hard-to-reach groups and individuals who may have otherwise gone undiagnosed. MHCs can play a complementary role also in universal coverage health systems, raising self-awareness of unreached population and making access to primary health care easier.

Breast Cancer Screening Program in Lithuania: Interval Cancers and Program Sensitivity After 7 Years of Mammography Screening

OBJECTIVE

Analysis of interval cancers is critical in determining the sensitivity of screening and represents an objective measure of the quality of mammography screening program (MSP).

METHODS

Period analyzed: from 2006 to 2012. The rate of screen-detected, interval cancers and program sensitivity were measured. A comparison of screen-detected and interval cancers was performed.

RESULTS

During the period of the study, 429 473 women were screened and 1297 were found to have cancer. The overall screen-detected cancer rate was 30.2 per 10 000 women screened. Four hundred thirty-one case of interval cancers have occurred during the period of the study. The interval cancer ratio (ICR) was 0.25. Overall sensitivity of MSP amounted to 75.1%. Slightly lower sensitivity was found among the youngest age-group, especially for those with lobular cancers. Interval cancers were bigger in size, more often with metastases in lymph nodes, than screen-detected cancers, but these differences were not statistically significant.

CONCLUSIONS

Overall program sensitivity in Lithuania is about 75%, ICR is 0.25, and these parameters are comparable to other European countries.

Evidence of interval cancer proportional incidence and review from mammography screening programs in Italy

Purpose

To summarize the existing evidence on the proportional incidence and review of interval cancers, as reported by Italian screening programs.

Material and methods

Literature search of published reports on: a) proportional incidence, determined according to breast cancers expected in the absnce of screening and estimated on the basis of patients/year at risk and age-specific incidence; and b) review of screening mammograms preceding interval cancers. Results were compared with European Commission recommended standards.

Results

Evidence on proportional incidence or review of interval cancers was reported by 37 and 24 local health unit programs, respectively. Compared to European Commission standards, 94% and 87% of programs complied at first interval cancers survey with recommended standards for proportional incidence or screening error rate at review, respectively. Two programs initially below acceptable standards reached satisfactory results at repeat evaluation over time.

Conclusions

Although they are a minority (20%) of all local health unit programs, which suggests a possible selection bias, Italian surveys reporting data on the proportional incidence or review of interval cancers show an overall good performance. Interval cancer survey appears feasible in any program and should become a routine procedure within the national quality control system.

A simple method to estimate the episode and programme sensitivity of breast cancer screening programmes

BACKGROUND

The estimation of breast cancer screening sensitivity is a major aim in the quality assessment of screening programmes. The proportional incidence method for the estimation of the sensitivity of breast cancer screening programmes is rarely used to estimate the underlying incidence rates.

METHODS

We present a method to estimate episode and programme sensitivity of screening programmes, based solely on cancers detected within screening cycles (excluding breast cancer cases at prevalent screening round) and on the number of incident cases in the total target population (steady state). The assumptions, strengths and limitations of the method are discussed. An example of calculation of episode and programme sensitivities is given, on the basis of the data from the IMPACT study, a large observational study of breast cancer screening programmes in Italy.

RESULTS

The programme sensitivity from the fifth year of screening onwards ranged between 41% and 48% of the total number of cases in the target population. At steady state episode sensitivity was 0.70, with a trend across age groups, with lowest values in women aged 50-54 years (0.52) and highest in those 65-69 (0.77).

CONCLUSIONS

The method is a very serviceable tool for estimating sensitivity in service screening programmes, and the results are comparable with those of other methods of estimation.

A pooled analysis of interval cancer rates in six European countries

The objective of this study was to assess detection rates and interval breast cancer (IC) rates from eight programmes in the European Breast Cancer Screening Network. A common data collection protocol was used to explore differences in IC rates among programmes and discuss their potential determinants. Pooled analysis was used to describe IC rates by age, compliance in screening, recall rate, screening detection (SD) rate and expected breast cancer incidence. Participation in screening averaged 77.9% (range 42.6-88.7%), recall rate 5.4% (range 3.3-17.7%) in the initial and 3.4% (range 1.8-8.9%) in the subsequent screening rounds, and SD rate was 60.4 (range 41.6-91) per 10 000 women in initial and 38.5 (range 31.3-62.6) in subsequent screens. IC rate during first 12 months after screening was 5.9 (range 2.1-7.3) per 10 000 women screened negative and 12.6 (range 6.3-15) in the second year of the interval. IC comprised 28% of the IC and SD cancers. The ratio between IC rate and expected incidence was 0.29 for the first 12 months and 0.63 for the 13-24 months period. Sensitivity was higher for the ages 60-69 years and for initial tests than subsequent tests. There were distinct differences in the IC rates between programmes. The results of this study reveal large variations in screening sensitivity and performance. Pooled evaluation of some process indicators within the European breast cancer screening programmes proved to be feasible and is likely to be useful for the future, particularly if it is performed regularly and extensively.

Incidence, detection, and tumour stage of breast cancer in a cohort of Italian women with negative screening mammography report recommending early (short-interval) rescreen

BACKGROUND

Although poorly described in the literature, the practice of early (short-interval) rescreen after a negative screening mammogram is controversial due to its financial and psychological burden and because it is of no proven benefit.

METHODS

The present study targeted an Italian 2-yearly screening programme (Emilia-Romagna Region, 1997-2002). An electronic dataset of 647,876 eligible negative mammography records from 376,257 women aged 50-69 years was record-linked with the regional breast cancer registry. The statistical analysis addressed the following research questions: (1) the prevalence of recommendation for early (<24 months) rescreen (RES) among negative mammography reports; (2) factors associated with the likelihood of a women receiving RES; and (3) whether women receiving RES and women receiving standard negative reports differed in terms of proportional incidence of interval breast cancer, recall rate at the next rescreen, detection rate of breast cancer at the next rescreen and the odds of having late-stage breast cancer during the interscreening interval and at the next rescreen.

RESULTS

RES was used in eight out of 13 screening centres, where it was found in 4171 out of 313,320 negative reports (average rate 1.33%; range 0.05%-4.33%). Reports with RES were more likely for women aged 50-59 years versus older women (odds ratio (OR) 1.33; 95% CI 1.25-1.42), for the first versus subsequent screening rounds (OR 1.91; 95% CI 1.79-2.04) and with a centre-specific recall rate below the average of 6.2% (OR 1.41; 95% CI 1.32-1.50). RES predicted a 3.51-fold (95% CI 0.94-9.29) greater proportional incidence of first-year interval cancers, a 1.90-fold (95% CI 1.62-2.22) greater recall rate at the next screen, a 1.72-fold (95% CI 1.01-2.74) greater detection rate of cancer at the next screen and a non-significantly decreased risk of late disease stage (OR 0.59; 95% CI 0.23-1.53).

CONCLUSION

The prevalence of RES was in line with the maximum standard level established by the Italian national guidelines. RES identified a subset of women with greater incidence of interval cancers and greater prevalence of cancers detected at the next screen.

Interval cancer incidence and episode sensitivity in the Norrbotten Mammography Screening Programme, Sweden

OBJECTIVES

To estimate the interval cancer incidence, its determinants and the episode sensitivity in the Norrbotten Mammography Screening Programme (NMSP).

SETTING

Since 1989, women aged 40-74 years (n = 55,000) have been invited to biennial screening by the NMSP, Norrbotten county, Sweden.

METHODS

Data on 1047 invasive breast cancers from six screening rounds of the NMSP (1989-2002) were collected. We estimated the invasive interval cancer rates, rate ratios and the episode sensitivity using the detection and incidence methods. A linear Poisson-model was used to analyse association between interval cancer incidence and sensitivity.

RESULTS

768 screen-detected and 279 interval cancer cases were identified. The rate ratio of interval cancer decreased with age. The 50-59 year age group showed the highest rate ratio (RR = 0.52, 95% CI 0.41-0.65) and the 70-74 year age group the lowest (RR = 0.23, 95% CI 0.15-0.36). The rate ratios for the early (0-12 months) and late (13-24 months) interval cancers were similar (RR = 0.18, 95% CI 0.15-0.22 and 0.20, 95% CI 0.17-0.24). There was a significantly lower interval cancer incidence in the prevalence round as compared with the incidence rounds. According to the detection method the episode sensitivity increased with age from 57% in the age group 40-49 years to 84% in the age group 70-74 years. The corresponding figures for the incidence method were 50% and 77%, respectively.

CONCLUSION

Our study showed an interval cancer incidence of 38% and the episode sensitivity of 62-73%, depending on the method of calculation. Our results are of clinically acceptable level and concert with the reference values of the European guidelines.

The other side of technology: risk of overdiagnosis of breast cancer with mammography screening

Estimates of overdiagnosis of breast cancer with mammography screening differ between studies. The estimate of overdiagnosis obtained using the cumulative incidence approach with data from randomized clinical trials ranges from 10 to 14%. In observational studies, where statistical adjustment for lead-time was utilized, the estimate was lower than 5% in two Italian studies, while it was quite higher in a Swedish study. Most of the differences are explained by different methodology, study design and measures. In this review we discuss the concept and the definition of the measure of overdiagnosis, and present different study methods to estimate overdiagnosis of breast cancer with mammography screening.

Quality of mammography screening in the Milan programme: evidence of improved sensitivity based on interval cancer proportional incidence and radiological review

BACKGROUND

Interval cancer (IC) incidence and review-based initial evaluation of Milan service screening (ASLMI1) suggested suboptimal performance. We report results in a subsequent screening round to further determine screening quality.

METHODS

IC was identified in subjects with a negative screening episode in 2005 (N=33,258) by linkage with 2005-2007 Hospital Discharge Records. IC proportional incidence-based sensitivity was estimated. Radiological review, with case-mix, was conducted in a blinded manner. Linkage and review modalities were maintained as for initial evaluation.

RESULTS

30 identified IC accounted for 6.99% (year 1), 27.84% (year 2), and overall 17.44% (2-year screening interval) proportional incidence. Estimated sensitivity was 93.01% (year 1), 72.16% (year 2) and 82.55% (2-year interval). Review classified 5 (16.6%) as screening error, 2 (6.7%) as minimal signs, and 23 (76.7%) as occult.

CONCLUSION

Programme sensitivity is now within recommended European standards. Performance indicators improved relative to initial evaluation. Both increasing experience and formal training of radiologists are likely to have contributed to this improvement.

Incidence of interval breast cancers after 650,000 negative mammographies in 13 Italian health districts

OBJECTIVES

To estimate the total proportional incidence of interval breast cancers in a two-yearly mammography screening programme, and to perform subgroup analyses by woman's age, screening centre-specific recall rate and screening round.

METHODS

Using unconverted electronic data-sets from the 13 screening centres in the Emilia-Romagna Region of northern Italy (540,450 women aged 50-69 years), a database of 919,538 mammography records was created. Of these, 655,175 eligible single-mammography records (1997-2002) from 379,318 women were record-linked with the regional Breast Cancer Registry. In the two-year inter-screening interval, a total of 1,022,694.3 woman-years at risk were accumulated, with 695 interval cancers observed and 2428.3 expected. The observed number of interval cancers was divided by the expected number to obtain the proportional incidence.

RESULTS

The total proportional incidence of first- and second-year interval cancers was 0.18 (95% CI 0.15-0.20) and 0.43 (0.39-0.47), respectively. Woman's age was inversely associated with proportional incidence in both interval years, with a cut-off point at age 60. A screening centre-specific recall rate greater than the regional average of 5% was associated with a proportional incidence of 0.14 (0.11-0.17) versus 0.20 (0.17-0.24) in the first interval year, and of 0.36 (0.31-0.41) versus 0.50 (0.44-0.56) in the second. The proportional incidence remained unchanged between the first and subsequent screening rounds.

CONCLUSIONS

The results were in line with the previous Italian data and with the recommended European standards. The inverse effect of woman's age and of recall rate was expected.

Full-Field Digital Versus Screen-Film Mammography: Comparative Accuracy in Concurrent Screening Cohorts

OBJECTIVE

The purpose of this study was to compare the diagnostic accuracy of digital mammography with that of screen-film mammography in concurrent cohorts participating in the same population-based screening program.

MATERIALS AND METHODS

In a retrospective study covering 2004-2005, we compared digital with screen-film mammography in two concurrent screening cohorts of women 50-69 years old participating in a screening program operated from mobile units. Each cohort had 14,385 participants matched by age and interpreting radiologist from all participants consecutively registered. We compared recall and cancer detection rates.

RESULTS

The recall rate was higher for digital mammography (4.56% vs 3.96%, p = 0.01), particularly when clustered microcalcifications were the only finding (1.05% vs 0.41%, p = 10(-6)) and for younger women (50-59 vs 60-69 years, 5.12% vs 4.17%, p = 0.009). The higher recall rate for digital mammography was mainly evident at incidence screening. The recall rate due to poor technical quality was lower with digital mammography (0.27% vs 0.50%, p = 0.002), possibly because real-time feedback was available. The detection rate was higher for digital mammography (0.72% vs 0.58%, p = 0.14), particularly for cancers depicted as clustered microcalcifications (0.26% vs 0.12%, p = 0.007), in younger (50-59 years) women (0.63% vs 0.42%, p = 0.09), and in denser breasts (1.09% vs 0.53%, p = 0.24). No significant difference was observed in positive predictive value on recall for digital mammography or screen-film mammography. Early cancer (pTis, pT1mic, pT1a) was more frequent in cancer detected with digital mammography than in that detected with screen-film mammography (41.3% vs 27.3%, p = 0.06).

CONCLUSION

Digital mammography may be more effective than screen-film mammography in contemporary screening practice in mobile units. The data indicate that digital mammography depicts more tumors than does screen-film mammography, especially lesions seen as microcalcifications. The potential association with improved outcome warrants further study.

Breast density as a determinant of interval cancer at mammographic screening

The association of breast density (% of breast volume involved by fibro-glandular densities) with the risk of interval cancer (IC) was investigated by reviewing a consecutive series of 346 cancers detected at screening (SDC) during 1996-1999 and of 90 ICs, reported as negative in the same period and diagnosed in the following 2 years, and comparing them to a random sample of 360 healthy controls. The probability of IC was significantly associated with breast density, whatever grouping (0/1-25/26-74/>74%; 0-25/26-60/61-74/>74%; 0-25/26-74/>74%) was considered (chi(2)=30.67-34.08, P<0.<0.01): 27.8% of all ICs were classified in the >74% density class, as compared to 7% of SDC and 5% of healthy controls. No significant association to IC was observed for Wolfe pattern (P2/Dy vs N1/P1: chi(2)=0.30, P=0.960), number of used mammographic views (single oblique vs oblique+craniocaudal: chi(2)=0.02, P=0.90) or screening round (first vs repeat: chi(2)=1.41, P=0.23). Multivariate analysis confirmed the independent association of breast density to IC, the highest risk being observed for >74% density class (OR vs 0% class=13.4, 95% CI 2.7-65.6, OR vs all other density classes=5.1, 95% CI 2.6-10.0). Age showed an independent association too, older women having a lower risk of IC (OR=0.52 95% CI 0.3-09). Breast density (>74%) resulted as being a major determinant of IC. Special screening protocols (shorter rescreening interval, routine use of ultrasonography) might be suggested for these subjects in order to improve screening sensitivity and efficacy.