Introduction Of Mammographic Screening Research Articles

Breast cancer mortality in Norway after the introduction of mammography screening

An organized mammography screening program was gradually implemented in Norway during the period 1996-2004. Norwegian authorities have initiated an evaluation of the program. Our study focused on breast cancer mortality. Using Poisson regression, we compared the change in breast cancer mortality from before to during screening in four counties starting the program early controlling for change in breast cancer mortality during the same time in counties starting the program late. A follow-up model included death in all breast cancers diagnosed during the follow-up period. An evaluation model included only breast cancers diagnosed in ages where screening was offered. The study group had been invited for screening one to three times and followed for on average of 5.9 years. In the follow-up model, 314 breast cancer deaths were observed in the study group, and 523, 404 and 638, respectively, in the four control groups. The ratio between the changes in breast cancer mortality between early and late starting counties was 0.93 (95% confidence interval [CI] 0.77-1.12). In the evaluation model, this ratio was 0.89 (95% CI: 0.71-1.12). In Norway, where 40% of women used regular mammography prior to the program, the implementation of the organized mammography screening program was associated with a statistically nonsignificant decrease in breast cancer mortality of around 11%.

Microcalcifications of the breast: a mammographic-histologic correlation study using a newly designed Path/Rad Tissue Tray

The introduction of screening mammography has brought about a greater knowledge of early breast cancer characteristics. These improvements have led to a reduction in size of suspicious lesions and a shift from surgical to image-guided core needle biopsies (CNBs). Establishing correlation between histologic and imaging findings is required for accurate diagnosis. Currently, there are no standardized multidisciplinary protocols for evaluating such lesions. We correlated histologic and radiologic findings in mammographically detectable calcified lesions in CNBs using specially designed Path/Rad Tissue Trays (patent pending, University of Kansas). Evidence of calcification was analyzed in 440 with and without the use of tissue trays. After mammographic identification of the lesion, CNBs are harvested, placed in tissue trays, and x-rayed to confirm sampling of the lesion. Images of CNBs with calcifications are marked by the radiologists and sent to the pathologist along with the biopsies. Trays with CNBs are then placed into cassettes and sent to the laboratory where they are embedded without disturbing orientation. Identification and localization of targeted microcalcifications were accomplished by radiologists and pathologists in 68 of 71 cases when using the tissue trays compared with 292 of 369 without tissue trays. Confirmation of microcalcifications was accomplished after deeper sectioning into tissue blocks from discordant cases. In conclusion, a systematic approach is recommended to standardize reporting of calcifications. The use of Path/Rad Tissue Trays has created a level of concordance between pathologists and radiologists that previously did no exist. It improved diagnostic reliability, encouraged communication between pathologists and radiologists, and minimized false diagnoses and/or delays in cancer diagnosis.

Trends in Breast Cancer Mortality in Sweden before and after Implementation of Mammography Screening

BackgroundIncidence-based mortality modelling comparing the risk of breast cancer death in screened and unscreened women in nine Swedish counties has suggested a 39% risk reduction in women 40 to 69 years old after introduction of mammography screening in the 1980s and 1990s.ObjectiveWe evaluated changes in breast cancer mortality in the same nine Swedish counties using a model approach based on official Swedish breast cancer mortality statistics, robust to effects of over-diagnosis and treatment changes. Using mortality data from the NordCan database from 1974 until 2003, we estimated the change in breast cancer mortality before and after introduction of mammography screening in at least the 13 years that followed screening start.ResultsBreast mortality decreased by 16% (95% CI: 9 to 22%) in women 40 to 69, and by 11% (95% CI: 2 to 20%) in women 40 to 79 years of age.DiscussionWithout individual data it is impossible to completely separate the effects of improved treatment and health service organisation from that of screening, which would bias our results in favour of screening. There will also be some contamination of post-screening mortality from breast cancer diagnosed prior to screening, beyond our attempts to adjust for delayed benefit. This would bias against screening. However, our estimates from publicly available data suggest considerably lower benefits than estimates based on comparison of screened versus non-screened women.

Localization of nonpalpable breast lesions

The introduction of mammography screening and improvements in diagnostic tools resulted in a major increase of breast cancers detectable as small, nonpalpable lesions suitable for breast-conserving treatment. Accurate preoperative localization of these cancers is a necessity. Several methods are available for localization, of which wire-guided localization is considered the current gold standard. Promising techniques are radio-guided occult lesion localization, radioactive seed localization and ultrasound-guided surgery. In this article, an overview of the various localization techniques is provided, describing advantages, shortcomings and effectiveness.

Characterizing the impact of 25 years of DCIS treatment

The significant increase in the detection and treatment of ductal carcinoma in situ (DCIS) since the introduction of screening mammography has not been accompanied by the anticipated reduction in invasive breast cancer (IBC) incidence. The prevalence of DCIS requires a reexamination of the population level effects of detecting and treating DCIS. To further our understanding of the possible impact of DCIS diagnosis and treatment on IBC incidence in the U.S., we simulated breast cancer incidence over 25 years under various assumptions regarding the baseline incidence of IBC and the progression of DCIS to IBC. The simulations demonstrate a tradeoff between the expected increased incidence of IBC absent any DCIS detection and treatment and the rate of progression of DCIS to IBC. Our analyses indicate that a high progression of DCIS to IBC implies a significant increase in incidence of IBC over what is observed had we not detected and treated DCIS. Conversely, if we assume that there would not have been a significant increase over and above the observed incidence evident in SEER, then our model indicates that the rate of DCIS progression to clinically significant IBC is low. Given the tradeoff illustrated by our model, we must reevaluate the assumption that DCIS is a short-term obligate precursor of invasive cancer and instead focus on further exploration of the true natural history of DCIS.

The emerging breast cancer epidemic: early diagnosis and treatment.

Breast cancer is the most common malignant tumour in women. Estimates for 2008 indicate that 1.38 million women were diagnosed and 0.46 million died from the disease worldwide [1]. Currently, the incidence in the developed and developing world is similar but, whereas incidence rates are tending to plateau or decline in the West, they are increasing in the developing world, presumably related to changes in dietary and reproductive behaviours and ageing populations [1]. Total mortality from breast cancer is already higher in the developing world [1]. Whilst mortality is declining in most western countries, it is estimated that it will increase by over 100% in developing countries by 2020 [2]. Whereas less than one-third of women diagnosed with breast cancer in developed countries die from the disease, this proportion reaches over two-thirds in developing countries and is directly related to income per capita (Figure ​(Figure1a)1a) [1,3]. Berry and colleagues [4] developed a series of independent statistical models of breast cancer incidence in order to determine the relative importance of the contribution of mammographic screening and adjuvant therapy to the marked decline in breast cancer mortality in the majority of developed countries. They estimated the mortality decline was related equally to screening and therapy and that mortality would increase in countries with limited facilities for screening and treatment (Figure ​(Figure1b1b). Figure 1 More deaths from breast cancer in the absence of early diagnosis and systemic treatment. (a) Income differences and differences between age-adjusted incidence and mortality (from [3] with permission). (b) Model of the estimates of the contribution of ... Early detection The analyses of Berry and colleagues and trials of screening indicate the importance of early detection by mammography. However, where mammographic screening is introduced into a country gradually, improvements in outcome are also seen in the non-screened group, which may, in part, be related to a general increase in awareness of the importance of early treatment [5,6]. Whilst randomised trials of breast self-examination versus no examination do not demonstrate the effectiveness of the intervention compared with women simply being made aware of breast examination [7], these studies do not address the issue of lack of awareness or of barriers to women presenting early rather than late. In many developing countries, the introduction of mammographic screening is currently not possible because of expense, the relatively low incidence of breast cancer and low age of diagnosis. Thus, the Early Resource Allocation Panel of the Breast Health Global Initiative (BHGI) produced guidelines suggesting a graded system of introduction for breast awareness and mammography based on whether the health care system was basic, limited, enhanced or maximal [8,9]. In countries with basic and limited resources they suggest the widespread introduction of culturally sensitive, linguistically appropriate, local education programmes to teach breast health awareness and awareness with mammography in countries with enhanced or maximal health care systems. An example is the Mumbai area in India, where mammography is not available but with education in the city two-thirds of women present with stage I and II breast cancer compared to only one-third in local rural populations (R Badwe, personal communication).

Disentangling the Roles of Mammographic Screening and HRT in Recent Breast Cancer Incidence Trends in Italy by Analyses Based on Calendar Time and Time Since Screening Activation

The aim of the study was to evaluate the roles of screening activation and hormone replacement therapy discontinuation on the recent declining breast cancer incidence trends in Italy. We analyzed 41,358 invasive female breast cancers incident during 1991-2004 in six Italian population-based cancer registries. Overall and age-specific incidence trends were evaluated using Joinpoint analysis. In addition to calendar years, data were analyzed on a years-since-screening-activation basis. Annual percentage change of standardized rates was computed. There were statistically significant increasing trends for women 40-44 and 45-49 years that did not change after screening activation. On the contrary, for women 50-69 years old and for those 70+ years, the increasing trends flattened around 2 years after screening activation. The prevalence of hormone replacement therapy use in Italy is and was rather low. In conclusion, the recent tendency toward stabilization observed in Italy for female breast cancer incidence rates in women aged 50 years or more follows the introduction of mammographic screening.

Breast cancer mortality in organised mammography screening in Denmark: comparative study

Objective To determine whether the previously observed 25% reduction in breast cancer mortality in Copenhagen following the introduction of mammography screening was indeed due to screening, by using an additional...

Estimates of overdiagnosis of invasive breast cancer associated with screening mammography

To estimate the extent of overdiagnosis of invasive breast cancer associated with screening in New South Wales, Australia, a population with a well-established mammography screening program which has achieved full geographic coverage. We calculated overdiagnosis as the observed annual incidence of invasive breast cancer in NSW in 1999-2001 (a screened population) minus the expected annual incidence in this population at the same time, as a percentage of the expected incidence. We estimated expected incidence without screening in 1999-2001 from the incidence of invasive breast cancer in: (1) women in unscreened age groups (interpolation method); and (2) women in all age groups prior to the implementation of screening (extrapolation method). We then adjusted these estimates for trends in major risk factors for breast cancer that may have coincided with the introduction of mammography screening: increasing obesity, use of hormone replacement therapy (HRT) and nulliparity. Finally, we adjusted for lead time to produce estimates of expected incidence in 1999-2001. These were compared with the observed incidence in 1999-2001 to calculate overdiagnosis of breast cancer associated with screening. Overdiagnosis of invasive breast cancer among 50-69 year NSW women was estimated to be 42 and 30% using the interpolation and extrapolation methods, respectively. Overdiagnosis of invasive breast cancer attributable to mammography screening appears to be substantial. Our estimates are similar to recent estimates from other screening programmes. Overdiagnosis merits greater attention in research and in clinical and public health policy making.

The Natural History of Invasive Breast Cancers Detected by Screening Mammography

The introduction of screening mammography has been associated with sustained increases in breast cancer incidence. The natural history of these screen-detected cancers is not well understood. We compared cumulative breast cancer incidence in age-matched cohorts of women residing in 4 Norwegian counties before and after the initiation of biennial mammography. The screened group included all women who were invited for all 3 rounds of screening during the period 1996 through 2001 (age range in 1996, 50-64 years). The control group included all women who would have been invited for screening had there been a screening program during the period 1992 through 1997 (age range in 1992, 50-64 years). All women in the control group were invited to undergo a 1-time prevalence screen at the end of their observation period. Screening attendance was similar in both groups (screened, 78.3%, and controls, 79.5%). Counts of incident invasive breast cancers were obtained from the Norwegian Cancer Registry (in situ cancers were excluded). As expected, before the age-matched controls were invited to be screened at the end of their observation period, the cumulative incidence of invasive breast cancer was significantly higher in the screened group than in the controls (4-year cumulative incidence: 1268 vs 810 per 100 000 population; relative rate, 1.57; 95% confidence interval, 1.44-1.70). Even after prevalence screening in controls, however, the cumulative incidence of invasive breast cancer remained 22% higher in the screened group (6-year cumulative incidence: 1909 vs 1564 per 100 000 population; relative rate, 1.22; 95% confidence interval, 1.16-1.30). Higher incidence was observed in screened women at each year of age. Because the cumulative incidence among controls never reached that of the screened group, it appears that some breast cancers detected by repeated mammographic screening would not persist to be detectable by a single mammogram at the end of 6 years. This raises the possibility that the natural course of some screen-detected invasive breast cancers is to spontaneously regress.

Why did some Danish counties introduce breast cancer screening and others not? An exploratory study of four selected counties

Of the fourteen counties and two municipalities that until recently were responsible for healthcare provision in Denmark, five introduced mammography screening (MS) programs. The objective of this research is to explain this decision-making variation and to gain insight into priority setting processes in health-care provision at the county level in Denmark. Literature on priority setting in health care was used to derive seven explanatory factors for comparing decision making on MS between four selected counties, of which two had implemented MS. The relative importance of each explanatory factor in each county was determined by analyzing policy documents, supplemented with interviews of selected stakeholders. The results were combined and compared at the county level. Evidence of effectiveness of MS was considered satisfactory and ethical issues related to MS were perceived relatively unproblematic only in those counties that introduced MS. Lack of resources, that is, radiologists, was an additional important factor for counties not implementing MS. Local opinion leaders have played a stimulating role, whereas advisory policy documents at the central government level and even legislation have had a minor impact. The four counties have based their decision making on the introduction of MS on different combinations of a limited number of factors that have been differentially weighted. The pattern of relevant factors in both counties not introducing MS is rather similar. The study elucidates the role of complementary factors to evidence in decision making. Of interest, recent public sector reforms have resulted in the decision to have MS implemented nationwide.

TREATMENT FOR DUCTAL CARCINOMA IN SITU IN AN ASIAN POPULATION: OUTCOME AND PROGNOSTIC FACTORS

Breast cancer is the most common cancer among Singapore women and ductal carcinoma in situ (DCIS) is believed to be the precursor of most invasive breast cancers. The incidence of DCIS has increased dramatically with mammographic screening, but its treatment remains controversial. Further, results of treatment for DCIS in Asians, and in particular Singapore women, are lacking. We review our institution's results treating a predominantly Chinese population with DCIS of the breast before the introduction of mammographic screening and aim to determine treatment outcomes and identify prognostic factors for disease recurrence. Between January 1994 and December 2000, 170 consecutive patients with DCIS were treated at our institution. One hundred and three (60.5%) were managed with breast conservation (17 with local wide excision alone and 86 with adjuvant irradiation following wide excision) whereas 67 (39.4%) underwent mastectomy. Of those who underwent wide local excision, 56 (54.3%) underwent re-excision for margin clearance. Overall, the axilla was surgically staged in 47 (27.6%) and no nodal involvement was found in all cases. Pathological specimens were reviewed by one of the authors. Median follow up was 86 months (range 4-151 months). Sixty-two patients (36%) were asymptomatic at presentation whereas most (64%) presented with clinical symptoms; out of these more than half (54%) presented with a palpable lump. The median size of tumours was 13 mm (range 1.5-90 mm). Patients who underwent breast conservation surgery had oncologically more favourable lesions - with a significantly higher incidence of smaller and non-palpable lesions and lesions of lower nuclear grade. However, there was also a significantly higher incidence of local recurrence in this group. At the end of follow up, there were 12 patients (7.1%) who developed local recurrence and 8 patients (4.7%) developed contralateral disease. The crude incidence of all breast events (including both local failure and contralateral events) at 5 years was 5.6%. Median time to the development of any breast event (local recurrence or contralateral disease) was 60 months (range 12-120 months). The cumulative 5-year recurrence-free survival for patients who underwent breast conservation surgery was 94%. Factors influencing local recurrence rate were close or involved margins (<or=1 mm) and lack of adjuvant radiotherapy. There were no cancer-specific deaths during the period of follow up. Our results indicate that rates of cancer-specific survival were similar after mastectomy and breast conserving surgery. However, a close or involved margin (<or=1mm) and lack of adjuvant radiotherapy were associated with local recurrence, with margin status being the independent predictor for local recurrence. Our results reinforce that optimizing local therapy is crucial to improve local control rates in women treated with DCIS in our population.

The origins of oestrogen receptor negative breast cancer

The origins of oestrogen receptor negative breast cancer

In Situ Carcinoma—Can We Predict which Patient Will Come Back with a Recurrence?

The frequency of in situ carcinomas has been rising since the introduction of mammographic screening. The management of patients with preinvasive disease remains difficult due to our lack of ability to accurately predict which patients will recur and progress to invasive carcinoma. Although some factors, such as lesion size and extent of margin clearance, are strong predictors of recurrence, many patients are still under- or overtreated. In this issue of Cancer Cell, Gauthier and colleagues suggest that abrogated response to cell stress measured by analysis of p16 and the proliferation marker Ki67 accurately predicts recurrence in ductal carcinoma in situ.

Pathological and Biological Differences Between Screen-Detected and Interval Ductal Carcinoma in situ of the Breast

BackgroundThe incidence of ductal carcinoma in situ (DCIS) has risen dramatically with the introduction of screening mammography. The aim was to evaluate differences in pathological and biological characteristics between patients with screen-detected and interval DCIS.MethodsFrom January 1992 to December 2001, 128 consecutive patients had been treated for pure DCIS at our institute. From these, 102 had been attending the Dutch breast cancer screening program. Sufficient paraffin-embedded tissue was available in 74 out of the 102 cases to evaluate biological marker expression (Her2/neu, ER, PR, p53 and cyclin D1) on tissue microarrays (TMA group). Differences in clinicopathological characteristics and marker expression between screen-detected and interval patients were evaluated. Screen-detected DCIS was classified as DCIS detected by screening mammography, when the two-year earlier examination failed to reveal an abnormality. Interval patients were classified as patients with DCIS detected within the two-year interval between two subsequent screening rounds.ResultsScreen-detected DCIS was related with linear branching and coarse granular microcalcifications on mammography (p < .001) and with high-grade DCIS according to the Van Nuys classification (p = .025). In univariate analysis, screen-detected DCIS was related with Her2/neu overexpression (odds ratio [OR] = 6.5; 95%CI 1.3–31.0; p = .020), and interval DCIS was associated with low-grade (Van Nuys, OR = 7.3; 95% CI 1.6–33.3; p = .010) and PR positivity (OR = 0.3; 95%CI 0.1–1.0; p = .042). The multivariate analysis displayed an independent relation of Her2/neu overexpression with screen-detected DCIS (OR = 12.8; 95%CI 1.6–104.0; p = .018).ConclusionsThese findings suggest that screen-detected DCIS is biologically more aggressive than interval DCIS and should not be regarded as overdiagnosis.

Proliferating activity in columnar cell lesions of the breast

With the introduction of mammographic screening, columnar cell lesions (CCLs) are observed more and more frequently because they are often associated with microcalcifications. Until now, the proliferative activity of these lesions has not been previously evaluated. Ki67 index was performed by immunohistochemistry in CCLs without atypia [columnar cell change (CCC) n = 20 and columnar cell hyperplasia without atypia (CCH without atypia) n = 20], flat epithelial atypia (FEA DIN1A n = 20), low-grade intraductal carcinoma (DIN1C n = 20), high-grade intraductal carcinoma (DIN 2-3 n = 20). Adjacent terminal duct-lobular unit (TDLU) of normal breast tissue served as control. Ki-67 index is extremely low and close in CCLs without atypia (CCC mean 0.1% and CCH mean 0.76%) and paradoxically is lower than in normal TDLU (mean 2.4%) (p < 0.001). In the FEA, in comparison with normal TDLU and CCLs without atypia, the Ki67 is higher (mean 8.2%) (p < 0.001) but extremely close to those of DIN1C (mean 8.9%) (p = 0.6 NS). Lastly, the Ki67 index is higher in DIN 2-3 (mean 25.4%) than in CCLs without atypia and FEA (p < 0.001). CCLs are disparate lesions having in common cells with columnar configuration but different proliferative characteristics. These data represent findings of biological interest which could help us to better understand these controversial lesions.

Cost‐effectiveness analysis of screening modalities for breast cancer in Japan with special reference to women aged 40–49 years

Although the introduction of screening mammography in Japan would be expected to reduce mortality from breast cancer, the optimal screening modality in terms of cost-effectiveness remains unclear. We compared the cost-effectiveness ratio, defined as the cost required for a life-year saved, among the following three strategies: (1) annual clinical breast examination; (2) annual clinical breast examination combined with mammography; and (3) biennial clinical breast examination combined with mammography for women aged 30-79 years using a hypothetical cohort of 100 000. The sensitivity, specificity and early breast cancer rates were derived from studies conducted from 1995 to 2000 in Miyagi Prefecture. The treatment costs were based on a questionnaire survey conducted at 13 institutions in Japan. We used updated parameters that were needed in the analysis. Although the effectiveness of treatment in terms of the number of expected survival years was highest for annual combined modality, biennial combined modality had a higher cost-effectiveness ratio, followed by annual combined modality and annual clinical breast examination in all age groups. In women aged 40-49 years, annual combined modality saved 852.9 lives and the cost/survival duration was 3 394 300 yen/year, whereas for biennial combined modality the corresponding figures were 833.8 and 2 025 100 yen/year, respectively. Annual clinical breast examination did not confer any advantages in terms of effectiveness (815.5 lives saved) or cost-effectiveness (3 669 900 yen/year). While the annual combined modality was the most effective with respect to life-years saved among women aged 40-49 years, biennial combined modality was found to provide the highest cost-effectiveness.

Breast cancer incidence after the introduction of mammography screening

A prevalence peak is expected in breast cancer incidence when mammography screening begins, but afterward the incidence still may be elevated compared with prescreening levels. It is important to determine whether this is due to overdiagnosis (ie, the detection of asymptomatic disease that would otherwise not have arisen clinically). In the current study, the authors examined breast cancer incidence after the introduction of mammography screening in Denmark. Denmark has 2 regional screening programs targeting women ages 50 years to 69 years. The programs were initiated in 1991 and 1993, respectively. No screening takes place in the 13 other Danish regions. Data regarding incident breast cancers detected between 1979 and 2001 were retrieved from the Danish Cancer Registry for each screening region and for the rest of Denmark, and time trends in rates for women ages 50 years to 69 years were compared. From 1 program, individual screening data were used to analyze breast cancer incidence in women who were never screened, those who were screened for the first time, or those who previously were screened. The incidence of breast cancer was found to have increased regardless of screening. In the screening regions, a marked prevalence peak was observed, and the incidence hereafter was compatible with the level indicated by the 95% confidence limits for the regression curves for the rates in the prescreening period, taking into account the artificial ageing in the program, the influx of newcomers, and variations in the data. Women who had undergone previous screening were found to have the same incidence of breast cancer as women who were never screened. The data from the current study do not provide evidence of overdiagnosis of invasive breast cancer in the 2 Danish screening programs or, if overdiagnosis was found to occur, it was only of limited magnitude.

Use of Statistics to Assess the Global Burden of Breast Cancer

A variety of statistics are used to quantify the burden (occurrence and outcome) of cancer generally and of breast cancer specifically. When undertaking any cancer control program, understanding these statistics, their source, and their quality is important for assessing the current situation, allocating resources to different control strategies, and evaluating progress. Two core statistics are the cancer incidence rate and the cancer mortality rate, which provide estimates of the average risk of acquiring and of dying from the disease, respectively. About 16% of the world's population is covered by registration systems that produce cancer incidence statistics, while mortality data are available for about 29%. Breast cancer incidence and mortality vary considerably by world region. In general, the incidence is high (greater than 80 per 100,000) in developed regions of the world and low (less than 30 per 100,000), though increasing, in developing regions; the range of mortality rates is much less (approximately 6-23 per 100,000) because of the more favorable survival of breast cancer in (high-incidence) developed regions. The incidence of breast cancer is increasing almost everywhere. This unfavorable trend is due in part to increases in risk factors (decreased childbearing and breast-feeding, increased exogenous hormone exposure, and detrimental dietary and lifestyle changes, including obesity and less physical activity). On the other hand, mortality is now decreasing in many high-risk countries due to a combination of intensified early detection efforts and the introduction of mammographic screening, resulting in the diagnosis of more small, early stage tumors, and advances in treatment.

Pathology reporting of breast cancer: trends in 1989-1999, following the introduction of mammographic screening in Western Australia

A survey of pathology reporting of breast cancer in Western Australia in 1989 highlighted the need for improvement. The current study documents (1) changes in pathology reporting from 1989 to 1999 and (2) changes in patterns of histopathological prognostic indicators for breast cancer following introduction of mammographic screening in 1989. Data concerning all breast cancer cases reported in Western Australia in 1989, 1994 and 1999 were retrieved using the State Cancer Registry, Hospital Morbidity data system, and pathology laboratory records. Pathology reports improved in quality during the decade surveyed. For invasive carcinoma, tumour size was not recorded in 1.2% of pathology reports in 1999 compared with 16.1% in 1989 (p<0.001). Corresponding figures for other prognostic factors were: tumour grade 3.3% and 51.6% (p<0.001), tumour type 0.2% and 4.1% (p<0.001), vascular invasion 3.7% and 70.9% (p<0.001), and lymph node status 1.9% and 4.5% (p = 0.023). In 1999, 5.9% of reports were not in a synoptic/checklist format, whereas all reports were descriptive in 1989 (p<0.001). For the population as a whole, the proportion of invasive carcinomas <1 cm was 20.9% in 1999 compared with 14.5% in 1989 (p<0.001); for tumours <2 cm the corresponding figures were 65.4% and 59.7% (p = 0.013). In 1999, 30.5% of tumours were histologically well-differentiated compared with 10.6% in 1989 (p<0.001), and 61.7% were lymph node negative in 1999 compared with 57.1% in 1989 (p = 0.006). Pure ductal carcinoma in situ (DCIS) constituted 10.9% and 7.9% of total cases of breast carcinoma in 1999 and 1989, respectively (p = 0.01). Quality of pathology reporting improved markedly over the period, in parallel with adoption of standardised synoptic pathology reports. By 1999, recording of important prognostic information was almost complete. Frequency of favourable prognostic factors generally increased over time, reflecting expected effects of mammographic screening.