The impact of mammography screening programmes on incidence of advanced breast cancer in Europe: a literature review

Background

Observational studies have reported conflicting results on the impact of mammography service screening programmes on the advanced breast cancer rate (ABCR), a correlation that was firmly established in randomized controlled trials. We reviewed and summarized studies of the effect of service screening programmes in the European Union on ABCR and discussed their limitations.

Methods

The PubMed database was searched for English language studies published between 01-01-2000 and 01–06-2018. After inspection of titles and abstracts, 220 of the 8644 potentially eligible papers were considered relevant. Their abstracts were reviewed by groups of two authors using predefined criteria. Fifty studies were selected for full paper review, and 22 of these were eligible. A theoretical framework for their review was developed. Review was performed using a ten-point checklist of the methodological caveats in the analysis of studies of ABCR and a standardised assessment form designed to extract quantitative and qualitative information.

Results

Most of the evaluable studies support a reduction in ABCR following the introduction of screening. However, all studies were challenged by issues of design and analysis which could at least potentially cause bias, and showed considerable variation in the estimated effect. Problems were observed in duration of follow-up time, availability of reliable reference ABCR, definition of advanced stage, temporal variation in the proportion of unknown-stage cancers, and statistical approach.

Conclusions

We conclude that much of the current controversy on the impact of service screening programmes on ABCR is due to observational data that were gathered and/or analysed with methodological approaches which could not capture stage effects in full. Future research on this important early indicator of screening effectiveness should focus on establishing consensus in the correct methodology.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4666-1) contains supplementary material, which is available to authorized users.

An audit of assessment procedures in women who develop breast cancer after a negative result

Objectives: A case audit was undertaken to determine the extent to which the early diagnosis of cancer could be improved by better adherence to screening guidelines, and to estimate the effect that this might have on breast cancer survival. Although affecting only a small proportion of the cancers of the screening programme, this exercise had an educational function for screening radiologists.

Setting: The East Anglian breast screening programme, a group of seven centres offering screening to a total population of 2.2 million inhabitants. Women were screened every three years between the ages of 50 and 64.

Methods: Adherence to the guidelines of the UK National Breast Screening Programme (as published in 2001) was tested in women assessed between the start of screening on 1 April 1989 and 31 December 1999, in cases where the screen was negative but who were subsequently diagnosed with breast cancer.

Results: In this period the programme screened 503,493 women, recalled 25,346 and diagnosed 3689 with cancer. 194 cancers in 193 women were reviewed, comprising those cancers that arose at the site of the lesion previously assessed. 96 women (49.5%) had calcifications, 48 (24.7%) had opacities. 139 of 194 cases were judged to have been inadequately assessed. A recurring theme showed that biopsies not undertaken or with false negative findings led to failure to diagnose lesions which were subsequently shown to be cancer. Microcalcifications and opacities were more likely to have been inadequately assessed than spiculate masses, parenchymal deformities, or asymmetric densities. In the earliest time period (1989–1993), there were a larger proportion of inadequately assessed cases than in the period 1994–1999.

Conclusion: Scrupulous adherence to good guidelines will result in a greater proportion of cancers being diagnosed. Failure to perform effective percutaneous biopsy was the usual cause of missed diagnoses. Although an infrequent occurrence this may have an effect on subsequent survival from breast cancer.

Variation in colorectal cancer treatment and survival: a cohort study covering the East Anglia region

AIM

National guidelines for colorectal cancer management aim to optimize cancer outcomes irrespective of postcode. However, in order to ensure equal performance of cancer services, variation in outcome must be monitored and intelligently assessed. In this study, detailed regional cancer registry data were used to quantify and explore the reasons for variation in colorectal cancer outcomes at nine hospitals in East Anglia.

METHOD

We analysed data on colorectal cancers registered by the Eastern Cancer Registry and Information Centre (ECRIC) between 1999 and 2005. Tumours were grouped by site, in keeping with surgical resection. Multivariable Cox regression models were used to identify the effects of patient, disease and treatment variables on an individual's risk of death.

RESULTS

After adjusting for demographic, disease and treatment variables there were significant differences in survival among hospitals in emergency admissions with cancer of the right colon, in elective admissions with cancer of the left, sigmoid or recto-sigmoid colon and in emergency admissions with cancer of the rectum. There were also differences among hospitals in terms of perioperative death, nonsurgical management and numbers of nodes examined. For rectal cancers, rates of anterior resection compared with abdominoperineal excision differed, as well as the use of neoadjuvant radiotherapy.

CONCLUSION

Detailed analysis of demographic, disease and treatment factors are required when comparing the survival of individuals with colorectal cancer across hospitals. The results imply that cancer management was not consistent across East Anglia in 1999-2005 but the reasons for this are uncertain. Nevertheless, 5-year age-standardized survival with colon cancer in the Anglia Cancer Network region is currently among the best in the UK.

Evaluation of mammographic surveillance services in women aged 40-49 years with a moderate family history of breast cancer: a single-arm cohort study

BACKGROUND

Women with a significant family history of breast cancer are often offered more intensive and earlier surveillance than is offered to the general population in the National Breast Screening Programme. Up to now, this strategy has not been fully evaluated.

OBJECTIVE

To evaluate the benefit of mammographic surveillance for women aged 40-49 years at moderate risk of breast cancer due to family history. The study is referred to as FH01.

DESIGN

This was a single-arm cohort study with recruitment taking place between January 2003 and February 2007. Recruits were women aged < 50 years with a family history of breast or ovarian cancer conferring at least a 3% risk of breast cancer between ages 40 and 49 years. The women were offered annual mammography for at least 5 years and observed for the occurrence of breast cancer during the surveillance period. The age group 40-44 years was targeted so that they would still be aged < 50 years after 5 years of surveillance.

SETTING

Seventy-four surveillance centres in England, Wales, Scotland and Northern Ireland.

PARTICIPANTS

A total of 6710 women, 94% of whom were aged < 45 years at recruitment, with a family history of breast cancer estimated to imply at least a 3% risk of the disease between the ages of 40 and 50 years.

INTERVENTIONS

Annual mammography for at least 5 years.

MAIN OUTCOME MEASURES

The primary study end point was the predicted risk of death from breast cancer as estimated from the size, lymph node status and grade of the tumours diagnosed. This was compared with the control group from the UK Breast Screening Age Trial (Age Trial), adjusting for the different underlying incidence in the two populations.

RESULTS

As of December 2010, there were 165 breast cancers diagnosed in 37,025 person-years of observation and 30,556 mammographic screening episodes. Of these, 122 (74%) were diagnosed at screening. The cancers included 44 (27%) cases of ductal carcinoma in situ. There were 19 predicted deaths in 37,025 person-years in FH01, with an estimated incidence of 6.3 per 1000 per year. The corresponding figures for the Age Trial control group were 204 predicted deaths in 622,127 person-years and an incidence of 2.4 per 1000 per year. This gave an estimated 40% reduction in breast cancer mortality (relative risk = 0.60; 95% confidence interval 0.37 to 0.98; p = 0.04).

CONCLUSIONS

Annual mammography in women aged 40-49 years with a significant family history of breast or ovarian cancer is both clinically effective in reducing breast cancer mortality and cost-effective. There is a need to further standardise familial risk assessment, to research the impact of digital mammography and to clarify the role of breast density in this population.

TRIAL REGISTRATION

National Research Register N0484114809.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 17, No. 11. See the HTA programme website for further project information.