Growth rate of invasive ductal carcinomas from a screened 50-74-year-old population.

Objective As breast cancer growth rate is associated with menopause, most screening programmes target mainly women aged 50-74. We studied the association between age at diagnosis and growth rate in this screening-specific age range. Methods We used data from breast cancer patients diagnosed in the screening programme in Nijmegen, the Netherlands. The data were restricted to the screening rounds when analogue mammography was used in both the screening and clinical setting. Growth rate expressed as tumour volume doubling time was based on increasing tumour size in longitudinal series of mammograms. Estimates were based on (a) tumours showing at least two measurable shadows, (b) tumours showing a shadow at detection only (left censored), and (c) tumours showing no growth (right-censored observation). All 293 tumours were consecutively diagnosed invasive ductal breast cancers in participants of the Nijmegen screening programme in the period 2000-2007. Results Depending on the assumptions made on tumour margins and mammographic density, the relation of volume doubling time with age non-significantly varies from a decrease of 3.3% to an increase of 1.4% for each year increase in age at diagnosis (all P-values ≥ 0.18). Applying left censoring on indistinct tumours, the geometric mean volume doubling time was 191 days (95% confidence interval 158-230). Conclusion We found no significant change in growth rate with age in women diagnosed with invasive ductal breast cancer in the screening age range 50-74. This outcome does not support differential screening intervals by age based solely on breast cancer growth rate for this particular group.

Predicting the stage shift as a result of breast cancer screening in low- and middle-income countries: a proof of concept.

OBJECTIVE: To provide proof of concept for a simple model to estimate the stage shift as a result of breast cancer screening in low- and middle-income countries (LMICs). Stage shift is an essential early detection indicator and an important proxy for the performance and possible further impact of screening programmes. Our model could help LIMCs to choose appropriate control strategies. METHODS: We assessed our model concept in three steps. First, we calculated the proportional performance rates (i.e. index number Z) based on 16 screening rounds of the Nijmegen Screening Program (384,884 screened women). Second, we used linear regression to assess the association between Z and the amount of stage shift observed in the programme. Third, we hypothesized how Z could be used to estimate the stage shift as a result of breast cancer screening in LMICs. RESULTS: Stage shifts can be estimated by the proportional performance rates (Zs) using linear regression. Zs calculated for each screening round are highly associated with the observed stage shifts in the Nijmegen Screening Program (Pearson's R: 0.798, R square: 0.637). CONCLUSIONS: Our model can predict the stage shifts in the Nijmegen Screening Program, and could be applied to settings with different characteristics, although it should not be straightforwardly used to estimate the impact on mortality. Further research should investigate the extrapolation of our model to other settings. As stage shift is an essential screening performance indicator, our model could provide important information on the performance of breast cancer screening programmes that LMICs consider implementing.

Breast cancer among women over 75 years: an important public health problem?

Women aged >75 years are not invited for mammographic screening; if diagnosed with breast cancer, due to their anticipated short-life expectancy, they are expected to die of other causes. To describe the breast cancer health problem in women aged >75 years, we estimated breast cancer incidence in this age group and the risk of breast cancer death in patients diagnosed after 75 years of age in Nijmegen, the Netherlands. Our findings demonstrate that in this age group, 3.3% of the women will be diagnosed with breast cancer, and that one in three of these incident cases die of this disease. These patients could have benefited from continued screening.

Residual confounding after adjustment for age: a minor issue in breast cancer screening effectiveness.

Residual confounding, after adjustment for age, is the major criticism of observational studies on breast cancer screening effectiveness. We developed realistic scenarios for the prevalence and strength of risk factors on screened and not screened groups, and explored the impact of residual confounding bias. Our results demonstrate that residual confounding bias is a minor issue in screening programme evaluations.

Effective biennial mammographic screening in women aged 40-49.

BACKGROUND: The United Kingdom is currently moving the age limit for invitation in its national breast screening programme downwards from 50 to 47. In contrast, the US Preventive Services Task Force concluded that, because of borderline statistical significance on effectiveness of mammographic screening, the current evidence is insufficient to advise screening in women aged 40-49. MATERIAL AND METHODS: We designed a case-referent study to investigate the effect of biennial mammographic screening on breast cancer mortality for women in their forties. In Nijmegen, the Netherlands, screening started in 1975. A total of 272 breast cancer deaths were identified, and 1360 referents aged 40-69 were sampled from the population invited for screening. Effectiveness was estimated by calculating the odds ratio (OR) indicating the breast cancer death rate in screened versus unscreened women. RESULTS: In women aged 40-49, the effect of screening was OR = 0.50 (95% confidence interval (CI) = 0.30-0.82). This result is similar to those aged 50-59 (OR = 0.54; 95% CI = 0.35-0.85) and 60-69 (OR = 0.65; 95% CI = 0.38-1.13). CONCLUSION: Our results add convincing evidence about the effectiveness of biennial mammographic screening in women aged 40-49.

A remarkable reduction of breast cancer deaths in screened versus unscreened women: a case-referent study.

OBJECTIVE: We designed a case-referent study to investigate the effect of mammographic screening at the individual level, looking at the association of breast cancer death with screening history. METHODS: The study population included all women aged 50-75 in the province of Limburg, the Netherlands who had been invited to the screening program from 1989 to 2006. From this population, 118 cases originated who died of breast cancer in 2004 or 2005. The screening history of these cases was collected and compared with a sample of the invited population. The breast cancer death rate in the screened relative to the unscreened women was estimated as the odds ratio (OR). This OR was adjusted for self-selection bias, the difference in baseline risk for breast cancer death between screened and unscreened women. RESULTS: Analysis of the data showed a breast cancer mortality reduction of 70% in the screened versus the unscreened women (OR = 0.30, 95% CI 0.14-0.63). The magnitude of self-selection was estimated specifically for Limburg. After correction for self-selection bias, the effect of screening increased to 76% (OR = 0.24, 95% CI 0.10-0.58). CONCLUSION: Screening resulted in a remarkable reduction in breast cancer mortality. Contrary to findings in other countries, adjustment for self-selection in Limburg had no influence on the impact of screening. Thanks to a well-organized centralized screening program, similar results are expected in other regions of the Netherlands.

Alcohol drinking in young adults: the predictive value of personality when peers come around.

This study examined whether personality traits and peer drinking affect alcohol consumption in young adults. Data were analyzed from a study that was conducted in a 'bar laboratory' in which ad-lib drinking of peer groups was observed. The findings indicate that extroversion is moderately associated with self-reported daily drinking, while low emotional stability is modestly associated with alcohol-related problems. With regard to drinking in the observational drinking setting, personality is not associated with young adults' actual alcohol consumption. Further, peer drinking levels were strongly related to young adults' drinking. Besides, agreeableness interacted with the effects of peer drinking on young adults' drinking in such a way that agreeable individuals adapted their actual alcohol consumption more easily than others when socializing in a high- or a low-drinking peer group. We concluded that drinking in a peer context, irrespective of personality, played a major role in forming young adults' drinking. However, personality (i.e. agreeableness) definitely played a role to the extent of the individuals' adaptation to peer drinking norms.