One- versus Two-View Mammography Screening

In order to compare mammography screening with one versus two views, a prospective population-based study was carried out. Mammograms from 12 636 women aged 40 to 54 years were examined first as one-view screening and later as two-view screening. The initial results showed that two-view screening resulted in 349 recalls, 72 surgical biopsies, and 32 breast cancers. One-view screening resulted in 542 recalls, 61 surgical biopsies, and 29 histologically proven breast cancers. The follow-up revealed 2 additional cancers detected by one-view screening. Thus, the use of two-view screening resulted in one more cancer case being detected. The difference in breast cancer detection was not significant.

Mammography casting-type calcification and risk of local recurrence in DCIS: analyses from a randomised study

BACKGROUND

We studied the association between mammographic calcifications and local recurrence in the ipsilateral breast.

METHODS

Case-cohort study within a randomised trial of radiotherapy in breast conservation for ductal cancer in situ of the breast (SweDCIS). We studied mammograms from cases with an ipsilateral breast event (IBE) and from a subcohort randomly sampled at baseline. Lesions were classified as a density without calcifications, architectural distortion, powdery, crushed stone-like or casting-type calcifications.

RESULTS

Calcifications representing necrosis were found predominantly in younger women. Women with crushed stone or casting-type microcalcifications had higher histopathological grade and more extensive disease. The relative risk (RR) of a new IBE comparing those with casting-type calcifications to those without calcifications was 2.10 (95% confidence interval (CI) 0.92-4.80). This risk was confined to in situ recurrences; the RR of an IBE associated with casting-type calcifications on the mammogram adjusted for age and disease extent was 16.4 (95% CI 2.20-140).

CONCLUSION

Mammographic appearance of ductal carcinoma in situ of the breast is prognostic for the risk of an in situ IBE and may also be an indicator of responsiveness to RT in younger women.

Differences in Endpoints between the Swedish W-E (Two County) Trial of Mammographic Screening and the Swedish Overview: Methodological Consequences

Objectives

To characterize and quantify the differences in the number of cases and breast cancer deaths in the Swedish W-E Trial compared with the Swedish Overview Committee (OVC) summaries and to study methodological issues related to trials in secondary prevention.

Setting

The study population of the W-E Trial of mammography screening was included in the first (W and E county) and the second (E-county) OVC summary of all Swedish randomized mammography screening trials. The OVC and the W-E Trial used different criteria for case definition and causes of death determination.

Method

A Review Committee compared the original data files from Wand E county and the first and second OVC. The reason for a discrepancy was determined individually for all non-concordant cases or breast cancer deaths.

Results

Of the 2615 cases included by the W-E Trial or the OVC, there were 478 (18%) disagreements. Of the disagreements 82% were due to inclusion/exclusion criteria, and 18% to disagreement with respect to cause of death or vital status at ascertainment. For E-County, the OVC inclusion rules and register based determination of cause of death (second OVC) rather than individual case review (W-E Trial and 1st OVC) resulted in a reduction of the estimate of the effect of screening, but for W-County the difference between the original trial and the OVC was modest.

Conclusions

The conclusion that invitation to mammography screening reduces breast cancer mortality remains robust. Disagreements were mainly due to study design issues, while disagreements about cause of death were a minority. When secondary research does not adhere to the protocols of the primary research projects, the consequences of such design differences should be investigated and reported. Register linkage of trials can add follow-up information. The precision of trials with modest size is enhanced by individual monitoring of case status and outcome status such as determination of cause of death.

Mammography and breast cancer: the new era

OBJECTIVES

To review the evidence demonstrating that early detection of breast cancer substantially decreases death from the disease, and to demonstrate that the significant change in the outcome of breast cancer patients results from a combination of early detection and surgical removal of breast cancer, as treatment of the late stage disease provides little impact on ultimate outcome.

METHOD

Review results of the randomized controlled trials of mammographic screening and the published results of service screening.

RESULTS

Both randomized controlled trials and service screening, when performed properly, provide unequivocal evidence demonstrating that arresting the disease in its preclinically detectable phase has significant impact on outcome. Primary emphasis should be upon preventing breast cancer from developing to metastatic disease.

CONCLUSIONS

Numerous scientific trials have repeatedly and convincingly confirmed that breast cancer is progressive rather than a systemic disease from its inception. Progression of breast cancer can be arrested through detection and treatment at an early phase. The time at which disease progression is arrested has significant impact on clinical outcome, making mammographic screening a key factor in the control of breast cancer.

Quantifying the potential problem of overdiagnosis of ductal carcinoma in situ in breast cancer screening

The relevance of detection of ductal carcinoma in situ (DCIS) in a breast cancer screening programme, and the extent of overdiagnosis of non-progressive lesions, remains controversial. It was the purpose of this paper to estimate the incidence of non-progressive, 'overdiagnosed' DCIS. We defined non-progressive DCIS (DCIS(0)) as DCIS which could not have progressed to invasive disease if left untreated. Progressive DCIS (DCIS(1)) was defined as DCIS which has the propensity to progress to invasive disease. We fitted a Markov process model of the incidence of progressive and non-progressive DCIS, the transition of the former to preclinical invasive disease and the subsequent progression to clinical symptomatic cancer. We used data from the Swedish Two-County Trial and from service screening programmes in the UK, Netherlands, Australia and the USA to estimate the incidence of progressive and non-progressive DCIS, and the detection rates of each at the first and subsequent screening. Average incidence of non-progressive DCIS was 1.11 per 100000 per year. Average incidence of progressive DCIS was 2.1 per 1000 per year. At prevalence screen, 37% of DCIS cases were estimated to be non-progressive. A woman attending prevalence screen has a 19 times greater chance of having a progressive DCIS or an invasive tumour diagnosed than of having a non-progressive DCIS diagnosed. At incidence screen, only 4% of DCIS cases were estimated to be non-progressive. A woman attending an incidence screen has a 166 times higher probability of having a progressive DCIS or invasive lesion diagnosed than of having a non-progressive DCIS diagnosed. There is an element of overdiagnosis of DCIS in breast cancer screening, but the phenomenon is small in both relative and absolute terms.

Oral contraceptive use and mammographic patterns

High-risk mammographic patterns represent an increased risk of contracting breast cancer and may be used as a surrogate endpoint for the disease. We examined the relationship between oral contraceptive (OC) use and mammographic patterns among 3218 Norwegian women, aged 40-56 years. Information on ever OC use, duration, and age of first OC use and other epidemiological data were obtained through questionnaires. The mammograms were categorized into five groups. Patterns I-III were combined into a low-risk group and patterns IV and V into a high-risk group. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression and adjusted for age, menopausal status, parity, age at first birth, and body mass index. Women who reported ever having used OCs were 20% more likely (OR 1.27, 95% CI 1.0-1.6) to have high-risk mammographic patterns compared with those reporting never having used OCs. There was no dose response between different measures of OC use and high-risk patterns. Among nulliparous women, ever OC users were four times more likely (OR 4.65, 95% CI 2.1-10.3) to have high-risk patterns compared with never users. Our findings suggest that, especially among nulliparous women, ever OC use may exert its effect on breast cancer risk through changes in breast tissue, which can be observed on a mammogram.

A treatment scale for axillary management in breast cancer

BACKGROUND

We have investigated a method, the Kaufman axillary treatment scale (KATS), to help assign patients with a clinically negative axilla to one of three current options of axillary management: standard axillary dissection, sentinel node sampling followed by axillary dissection if the sentinel node is positive, or no axillary surgery at all. The KATS score uses preoperative data to guide the choice of axillary treatment.

METHODS

The KATS score is calculated by adding the preoperative values of tumor size, patient age, and pathologic grade. Values range from 1 to 4 for size (1 to 9 mm, 10 to 14 mm, 15 to 19 mm, and 20 to 30 mm), 1 to 3 for age (70 years and over, 50 to 69 years, less than 50 years), and 1 to 2 for grade (low or not low) to calculate the score. The KATS score ranges from 3 to 9. We have applied this score against the SEER (Surveillance, Epidemiology, and End Results) tumor registry of 529 patients with invasive breast cancer with known pathologic data. We then validated it by applying it to our own set of 190 patients using preoperative data. The chi-square test and logistic regression analysis were used for P values (all two sided), univariate and multivariate analysis, odds ratio and confidence intervals utilizing SPSS statistics software.

RESULTS

In the SEER database using American Joint Committee on Cancer pathologic size alone, no sizable group was identified with a positive node rate neither below 8% (T1a) nor above 48% (T2). KATS scores of 3 and 4 (68 patients, group 1) identify patients with an average node positive rate of 4.4% (P <0.02, group 1 versus 2). Those patients with KATS scores of 5, 6, and 7 (341 patients, group 2) carry an average node positive rate of 22% (P <0.001, group 2 versus 3). KATS scores of 8 and 9 (120 patients, group 3) identify patients with an average node positive rate of 50% (P <0.001, group 3 versus 1). Similar results were found on our own group of 190 patients using preoperative available data. KATS scores of 3 or 4 (11 patients, group 1) had no positive nodes. Group 2 (100 patients, KATS score 5, 6, and 7) had an average 30% node positive rate. Group 3 (79 patients, KATS score 8 and 9) had 61% node positive rate. The KATS score allows the clinician to separate patients into three axillary management groups. Group 1 are those patients who may need no axillary surgery at all. Group 2 are patients who would benefit from sentinel node mapping. Group 3 has a node positive rate (61%) similar to that of clinically palpable nodes (since not all clinically palpable nodes are positive). Group 3 patients may be considered for standard axillary dissection, similar to the palpable node patient. If group 3 patients have sentinel node mapping, more than half of these patients require axillary dissection and the impact of false negative sentinel node procedures may become clinically significant.

CONCLUSIONS

An axillary treatment score has been developed to aid in the triage of patients toward reasonable axillary treatment choices for the benefit of the patient. The KATS score is a guideline and not a mandate. The KATS score attempts to use breakpoints that are both clinically practical and validated by scientific data. Like many other attempts to categorize patients, there is a continuum of data points along any variable. The treating physician utilizing the full array of available data on each patient makes the final clinical decision of axillary management.

Beyond randomized controlled trials: organized mammographic screening substantially reduces breast carcinoma mortality

BACKGROUND

The efficacy of mammographic screening in the reduction of breast carcinoma mortality has been demonstrated in randomized controlled trials. However, the evaluation of organized screening outside of research settings (so-called "service screening") faces unique methodologic and conceptual challenges. The current study describes the evaluation of organized mammography screening in a clinical setting and demonstrates the benefit obtained from service screening in two Swedish counties.

METHODS

In the group of subjects ages 20--69 years, there were 6807 women diagnosed with breast carcinoma over a 29-year period in 2 counties in Sweden and 1863 breast carcinoma deaths. All patients were classified from patient charts based on their screening status (i.e., whether they had been invited to undergo screening and whether they actually had undergone screening). The number of women who lived in the 2 counties during the 29-year study period was provided by the Central Bureau of Statistics. Breast carcinoma-specific mortality was compared across three time periods: 1) 1968--1977, when no screening was taking place because mammography had not been introduced; 2) 1978--1987, the approximate period of the Two-County randomized controlled trial of screening in women ages 40--74 years; and 3) 1988--1996, when all women in the 2 counties ages 40--69 years were invited to undergo screening (service screening). When comparing breast carcinoma mortality in screened women with that in women diagnosed before screening was introduced, a correction for self-selection bias was incorporated to prevent overestimation of the benefit of screening.

RESULTS

The mortality from incident breast carcinoma diagnosed in women ages 40-69 years who actually were screened during the service screening period (1988--1996) declined significantly by 63% (relative risk [RR] = 0.37; 95% CI, 0.30--0.46) compared with breast carcinoma mortality during the time period when no screening was available (1968--1977). The mortality decline was 50% (RR = 0.50; 95% CI, 0.41--0.60) when breast carcinoma mortality among all women who were invited to undergo screening (nonattendees included) was compared with breast cancer mortality during the time period when no screening was available (1968--1977). The reduction in mortality observed during the service screening period, adjusted for selection bias, was 48% (RR = 0.52; 95% CI, 0.43--0.63). No significant change in breast carcinoma mortality was observed over the three time periods in women who did not undergo screening. This group included women ages 20--39 years because these individuals were never invited to undergo screening, and women ages 40--69 years who did not undergo screening (not invited during the randomized trial or invited during the second and third time periods but declined).

CONCLUSIONS

Regular mammographic screening resulted in a 63% reduction in breast carcinoma death among women who actually underwent screening. The policy of invitation to organized screening with mammography appears to have reduced breast carcinoma mortality by 50% in these 2 counties.

The pressing need for better histologic-mammographic correlation of the many variations in normal breast anatomy

Mammography screening calls for a reevaluation of the working relationship between physicians dealing with the diagnosis and treatment of breast diseases. In this new era, histologic-mammographic correlation needs to be extended to correctly describe the deceptive mammographic findings that correspond to variations in normal breast tissue. Progress in histologic-mammographic correlation can only be made by overcoming the limitations inherent to the traditional histologic technique by examining a histologic specimen of greater length, width, and depth. There are several distinct advantages to using the large-section histology technique in the diagnosis of breast diseases. The subgross (three-dimensional) histology technique serves to bridge the gap that separates the pathologist and radiologist, bringing them to a common ground for a better understanding of breast morphology. These improvements in communication between the members of the diagnostic team will serve to optimize the sensitivity and specificity of breast cancer diagnosis.

The Swedish Two-County Trial twenty years later. Updated mortality results and new insights from long-term follow-up

The benefit of invitation to mammographic screening observed in this trial is maintained as a highly significant 32% reduction in breast cancer mortality. Mammographic screening for breast cancer continues to save lives after up to 20 years. Screening derives this benefit by improving the distribution of tumors diagnosed with respect to prognostic categories based on node status, size, and histology of tumors. There is potential for modern screening programs with shorter interscreening intervals to achieve even greater improvements in prognostic category and greater reductions in breast cancer mortality. Mammography can discriminate a subpopulation of high-risk cases, those displaying casting-type calcifications on the mammogram, among very small tumors, with fundamental implications for diagnosis and treatment.

A new era in the diagnosis of breast cancer

The regular use of high-quality mammography on asymptomatic women enables most breast cancers to be detected in the preclinical phase. Earlier detection dramatically rearranges the spectrum of breast cancer outcomes, resulting in better control of breast cancer. The new era requires a shift in thinking and a re-evaluation of the traditional diagnostic and therapeutic approaches to breast diseases. Tumors are smaller, less often node-positive, and have a more favorable malignancy grade. The challenge for diagnosticians is to find as many breast cancers as possible in the preclinical phase. The challenge for therapists is to adapt the treatment guidelines accordingly, in order to avoid over-treatment.

A novel method for prediction of long-term outcome of women with T1a, T1b, and 10-14 mm invasive breast cancers: a prospective study

BACKGROUND

Women with small mammographically detected breast cancers generally have good long-term outcomes, but a few with T1a (1-5 mm) and T1b (6-10 mm) tumours will eventually die from breast cancer. We investigated whether women at high risk of breast-cancer death could be identified with mammographic criteria and differentiated from women with small cancers of the breast and good outcomes.

METHODS

We prospectively applied mammographic classifications of tumour type to a consecutive series of 343 mammograms of invasive breast cancers of size 1-14 mm. Classifications were: stellate (spiculated) mass with no calcifications; circular or oval lesions with no calcifications; spiculated or circular lesions with non-casting-type calcifications; and casting-type calcifications.

FINDINGS

20-year survival for women with 1-14 mm invasive tumours with casting-type calcifications was 55%. 14% of 138 women with 1-9 mm tumours had casting-type calcifications on mammography, which accounted for 73% of all breast-cancer deaths (p<0.001). T1a, T1b, and 10-14 mm tumours with casting-type calcifications behaved as if they were larger lesions, since the rate of death was similar to that for women with advanced high-grade tumours. Most women who died were node-negative. The long-term survival of women who had tumours of 1-9 mm with no casting-type calcifications was about 95%.

INTERPRETATION

Mammographic classification seemed to reliably predict good and bad long-term outcomes for survival in tumours of 14 mm or smaller, and especially for those smaller than 10 mm. The implications for therapy are substantial.

10-Year results after sector resection with or without postoperative radiotherapy for stage I breast cancer: a randomized trial

PURPOSE

To study the long-term effectiveness of postoperative radiotherapy after sector resection for breast cancer in a randomized trial in which mammography is a major pathway to diagnosis.

PATIENTS AND METHODS

Three hundred eighty-one women with a unifocal breast cancer < or = 20 mm in diameter on the preoperative mammogram and without histopathologic signs of axillary metastases were treated by sector resection plus axillary dissection. Of these patients, 184 women were randomized to receive postoperative radiotherapy to the breast (XRT group), and 197 women received no further treatment (non-XRT group).

RESULTS

The local recurrence rate was 8.5% (95% confidence interval [CI], 3.9% to 13.1%) in the XRT group and 24.0% (95% CI, 17.6% to 30.4%) in the non-XRT group (P =.0001). Survival free from regional and distant recurrence was 83. 3% in the XRT group (95% CI, 77.5% to 89.1%) and 80.0% in the non-XRT group (95% CI, 73.9% to 86.1%) (P =.23). Overall survival was 77.5% in the XRT group (95% CI, 70.9% to 84.1%) and 78% in the non-XRT group (95% CI, 71.7% to 84.3%) (P =.99). A subgroup analysis suggested that women older than 55 years of age without comedo or lobular carcinomas had a low risk of local recurrence of 6.1% (95% CI, 0.1% to 9.1%) in the XRT-group and 11.0% (4.0% to 18.0%) in the non-XRT group (P =.16).

CONCLUSION

Sector resection plus radiotherapy resulted in an absolute reduction in local recurrence of 16% at 10 years compared with surgery alone. Women older than 55 years of age without comedo or lobular carcinomas may have a low risk of local recurrence. Postoperative radiotherapy was not shown to reduce distant recurrences or improve overall survival.

Markov models of breast tumor progression: some age-specific results

Researchers have noted that mammographic screening has a reduced effect on breast cancer mortality in women in their forties compared to older women. Explanations for this include poorer sensitivity in younger women due to denser breast tissue, as well as more rapid tumor progression, giving a shorter mean sojourn time (the average duration of the preclinical screen-detectable period). To test these hypotheses, we developed a series of Markov-chain models to estimate tumor progression rates and sensitivity. Parameters were estimated using tumor data from the Swedish two-county trial of mammographic screening for breast cancer. The mean sojourn time was shorter in women aged 40-49 compared to women aged 50-59 and 60-69 (2.44, 3.70, and 4.17 years, respectively). Sensitivity was lower in the 40-49 age group compared to the two older groups (83%, 100%, and 100%, respectively). Thus, both rapid progression and poorer sensitivity are associated with the 40-49 age group. We also modeled tumor size, node status, and malignancy grade together with subsequent breast cancer mortality and found that, to achieve a reduction in mortality commensurate with that in women over 50, the interscreening interval for women in their forties should be less than two years. We conclude that Markov models and the use of tumor size, node status, and malignancy grade as surrogates for mortality can be useful in design and analysis of future studies of breast cancer screening.

Recent results from the Swedish Two-County Trial: the effects of age, histologic type, and mode of detection on the efficacy of breast cancer screening

The effect of mammographic screening in reducing mortality from breast cancer is known to be smaller and more delayed in women aged 40-49 than in women over 50. In this study, we investigated how these phenomena relate to histology-specific breast cancer incidence and mortality. The data are from 2,468 women with breast cancer who participated in the Swedish Two-County Trial. The overall relative breast cancer mortality of invited to noninvited women aged 40-49 was 0.87, and the relative mortality from poorly differentiated (grade 3) ductal carcinoma was 0.95. These results were not statistically significant. The corresponding relative risks for invited women aged 50-74 were a statistically significant 0.65 and 0.61. We conclude that in this trial, with a two-year interscreening interval, the smaller and later effect of invitation to screening on breast cancer mortality in women 40-49 years old is due to the failure of screening to reduce mortality from grade 3 ductal carcinoma in this age group.

Updated overview of the Swedish Randomized Trials on Breast Cancer Screening with Mammography: age group 40-49 at randomization

The purpose of this overview is to estimate more precisely the long-term effect of mammography screening by adding four more years of follow-up to women aged 40-49 years in the four Swedish trials on mammography screening. Data from the four, trials were merged and linked to the Swedish Cancer and Cause of Death Register for 1958-1993 and 1951-1993 respectively to identify date of breast cancer diagnosis and cause and date of death. The invited and control groups comprised 48,569 and 40,247 women respectively. At the December 1993 follow-up, 602 and 482 breast cancer cases were identified in the two groups respectively, of which 104 and 111 had breast cancer as the underlying cause of death. This corresponds to a relative risk (RR) of 0.77 (95% CI: 0.59-1.01) for the two groups. In the 40-44 age group at randomization, 94% of breast cancer patients in the study and 89% in the control group were diagnosed before the age of 50; however, among breast cancer deaths in this age group, only two in the invited and five in the control group died after age 50. At follow-up of women 40-44 years at randomization 208 women in the invited and 184 in the control group were reported to the Cancer registry with breast cancer. Out of these 195 (94%) and 163 (89%) respectively were reported before the age of 50. Further, the relative risk for the age group 40-44 years at randomization by age at follow-up was 1.11, 0.51 and 0.46 for the age groups 45-49, 50-54, and 55-59 at follow-up. This study shows a 23% reduction in the breast cancer mortality in women 40-49 years at randomization achieved from a median trial time of 7.0 years, a median follow-up time of 12.8 years, and a screening interval of 18-24 months. Almost all of the effect in the 40-44 year age group at randomization was due to screening before the age of 50.

Risk factors for local recurrence after conservative treatment in stage I breast cancer. Definition of a subgroup not requiring radiotherapy

BACKGROUND

Risk factors for local recurrence after breast-conserving treatment of early breast cancer have not previously been evaluated in settings where mammography has been a major pathway to diagnosis of both primary tumour and recurrences or in patients treated surgically by a formal sector resection.

PATIENTS AND METHODS

Three hundred eighty-one women with stage 1 primary breast cancer were randomised after a standardised sector resection to either a course of postoperative radiotherapy to 54 Gy to the breast (XRT group) or to surgery alone (non XRT group). At five years, 43 local recurrences, six of them in the XRT group, appeared. Patient characteristics collected from the medical records, histopathological characteristics determined by re-examination of slides, and mammographic characteristics from the pre-operative mammograms were evaluated as risk factors for recurrence by univariate and multivariate Cox proportional hazards models. Results are reported as relative hazards (RH) with 95% confidence intervals (95% CI).

RESULTS

In the univariate analysis comedo cancer, RH 3.5 (95%, CI 18 6.7), lobular cancers RH 2.8 (95% CI 1.1 7.1), mammographic appearance as circular/oval shaped density, RH 2.3 (95% CI 1.1 4.51, and mammographic appearance as a stellate lesion with microcalcifications inside the lesion, RH 3.8 (95% CI 1.1-13.0) were identified as risk factors for local recurrence. Age, with a RH of 0.97 (95% CI 0.94 0.99) for each increasing year was inversely associated with risk. A multivariate analysis, which also took postoperative radiotherapy into account, only showed comedo cancers with a RH 2.6 (95% CI 1.3-5.0) and mammographic appearance of a stellate lesion with microcalcification inside the lesion RH 4.5 (95% CI 1.1-17.6) to be statistically significant. The estimates for age RH 0.98 (95% CI 0.95 1.01 and lobular cancers RH 2.5 (95%, CI 0.98 6.6) were marginally changed, with widened CIs. Patients > 60 years of age, without comedo or lobular carcinomas were found to be at low risk 15.9% at five years in Kaplan Meyer estimate) of local recurrence, even without postoperative radiotherapy.

CONCLUSION

Low age, comedo and lobular cancers and mammographic appearance of the tumour as a stellate lesion with microcalcifications inside the lesion indicate an increased risk for local recurrence after sector resection in stage 1 tumours at five years. Patients > 60 years of age without comedo or lobular cancers are at low risk for local recurrence at five years even without postoperative radiotherapy.

The Tabár classification of mammographic parenchymal patterns

The purpose of this study was to describe one method of classification, based on anatomic-mammographic correlations, developed by Tabár. We also wanted to examine how the mammograms categorized as low- and high-risk according to Tabár and Wolfe criteria related to each other and to three selected risk factors for breast cancer. The study materials are based on questionnaires and mammograms from 3,640 Norwegian women, aged 40-56 years, participating in the third Tromsö study. The mammograms were categorized into five groups. Line drawings and their pathologic correlates of the five patterns are described in detail. The Tabár classification is based on anatomic-mammographic correlations, following three-dimensional (thick slice technique) histopathologic-mammographic comparisons, rather than simple pattern reading (Wolfe classification). For analysis patterns I-III (Tabár) and N1 and P1 (Wolfe) were grouped into low-risk groups and patterns IV and V (Tabár) and P2 and DY Wolfe) into high-risk groups. The overall agreement on high-risk versus low risk for the two classifications was 54% with a kappa-value of 0.22. The study displays that the strength of association between high-risk mammographic patterns and the three selected risk factors parity, number of children and age at first birth is of greater magnitude when the Tabár instead of the Wolfe classification is applied. More patients are needed to compare the classification directly with the risk of cancer. This study indicates that further development of the classification of mammograms may increase the usefulness of mammographic patterns in research and clinical practice.

The Swedish randomised mammography screening trials: analysis of their effect on the breast cancer related excess mortality

OBJECTIVE

To apply an indirect method for estimation of the breast cancer related excess mortality in the Swedish randomised mammography screening trials.

SETTING

Randomised trials on mammography screening have, in Sweden, been performed in the counties of Kopparberg (W) and Ostergötland (E), the so called WE study, and in the three largest cities in Sweden, Stockholm (southern part), Gothenburg, and Malmö. An overview of the trials was presented in the Lancet in 1993 and included 156,911 women in the invited group and 125,866 in the control group.

METHODS

The excess mortality in the breast cancer subgroups was estimated by indirect standardisation using official national cause of death statistics according to Statistics Sweden as a reference.

RESULTS

The estimated reduction of the breast cancer related mortality was 24% for the whole group (40-74 years at randomisation). The corresponding figures for the age groups 40-49, 50-59, and 60-69 years were 6%, 28%, and 34% respectively.

CONCLUSION

The results are very similar to those presented earlier based on the traditional comparison of the breast cancer mortality in the invited and in the control group. This analysis further strengthens previous reports on a beneficial effect of mammography screening, which is especially pronounced in the age group 50-69.

One- versus two-view mammography screening. A prospective population-based study

In order to compare mammography screening with one versus two views, a prospective population-based study was carried out. Mammograms from 12,636 women aged 40 to 54 years were examined first as one-view screening and later as two-view screening. The initial results showed that two-view screening resulted in 349 recalls, 72 surgical biopsies, and 32 breast cancers. One-view screening resulted in 542 recalls, 61 surgical biopsies, and 29 histologically proven breast cancers. The follow-up revealed 2 additional cancers detected by one-view screening. Thus, the use of two-view screening resulted in one more cancer case being detected. The difference in breast cancer detection was not significant.

Control of breast cancer through screening mammography

There are more than 100 different malignancies that may develop in the human body. Unfortunately, very few of them can be controlled. Those we can control are not the most frequently occurring. Clinical research has made significant improvements in the past decades, attacking on all possible fronts: prevention, diagnosis/detection, and therapy. This overview article describes research results of the past 3 decades, demonstrating that early detection of breast cancer alters the natural history of the disease.

The present state of screening for breast cancer

The results to date are convincing enough to justify recommending large scale mammography screening. The International Union Against Cancer (UICC) Workshop on screening for breast cancer in 1986 concluded that "In countries where breast cancer is common and where the necessary resources are available, screening using mammography alone or mammography plus physical examination is applicable as public health policy." The Swedish government has recommended screening with mammography for all women aged 40-74. This recommendation repeatedly emphasizes the necessity of high-quality examinations interpreted by well-trained radiologists. Screening with mammography is bringing breast cancer patients to therapy at a far earlier stage in the development of the disease. This calls for a re-evaluation of therapeutic methods.

The control of breast cancer through mammography screening. What is the evidence?

There are few forms of cancer that can be effectively controlled. Now that there is sufficient evidence demonstrating that mortality from breast cancer can be reduced with the help of mammography screening, we are faced with the challenge of applying this method on a large scale. What are the major practical problems? The medical profession and decision makers must be made familiar with nature of the recent achievements and with their practical implications. The personnel who will be responsible for undertaking screening have to be adequately trained before screening gets under way. Women should understand the benefits that they can gain from mammography screening so that they will be sufficiently motivated to attend. This can be achieved by sincere, periodic information through the mass media. It is important that every woman eligible for screening understand that her risk of dying from breast cancer will be half as much if she participates in screening as it would be if she fails to participate. She should also be aware that the smaller cancers detected at screening can often be removed by breast conserving surgery without the need for mastectomy. Because mammography does not prevent breast cancer, women must be aware of the fact that mammography has to be repeated at regular intervals if the benefits of screening are to be maintained. Additionally, breast self-examination should be practiced in the interval between screens. Finally, decision makers will have to realize that screening with mammography can, in the long run, lead to reduction of health service costs. It is obvious that the expenses involved in taking care of a patient with advanced breast carcinoma can be very high. As it has been clearly demonstrated that properly performed screening will significantly decrease the number of advanced, costly breast carcinomas, a large proportion of these expenses will be saved in the population invited to screening. Because screening itself drains economic resources, the costs of screening outweigh the savings until the number of advanced cancers decreases; however, after this occurs the expenses of screening will be far less than the savings. The savings arise from the smaller number of advanced, costly cases. The results to date are convincing enough to justify recommending large-scale mammographic screening. The Swedish government has recommended screening with mammography for all women aged 40-74. This recommendation repeatedly emphasizes the necessity of high quality examinations interpreted by well-trained radiologists.

What is the optimum interval between mammographic screening examinations? An analysis based on the latest results of the Swedish two-county breast cancer screening trial

Further results are presented from the Swedish two-county breast cancer screening trial. The reduction in the rate of advanced cancers and of breast cancer mortality in the group allocated to screening when compared to the control group has accelerated with a further year of follow-up. Mortality due to other causes and the rate of other cancers remains similar in the two groups. Attention has been focused on the rate at which cancers start re-emerging among women with negative mammograms. Among women over 50 years of age at entry to the study, relatively few interval cancers are seen in the first two years after a screening test; in the third year the rate rises to nearly 50% of the comparable rate in the control group. Among women aged 40-49 years at entry, by contrast, the rate of interval cancers even in the first post screening year is nearly 40% of that in the controls and in the second year nearly 70%. In older women in the group allocated to screening, much of the breast cancer mortality comes from the refusers and little from the interval cancers; in younger women the picture is reversed. The implications for screening policy, including the interscreening interval are discussed.

Reduction in mortality from breast cancer after mass screening with mammography. Randomised trial from the Breast Cancer Screening Working Group of the Swedish National Board of Health and Welfare

A randomised controlled trial to investigate the efficacy of mass screening with single-view mammography in reducing mortality from breast cancer was started in Sweden in 1977. 162 981 women aged 40 years or more and living in the counties of Kopparberg and Ostergötland were enrolled in the study and divided at random into 2 groups. Each woman in the study group was offered screening every 2 or 3 years depending on age. Women in the control group were not offered screening. This report is confined to the 134 867 women aged 40-74 years at date of entry. The results to the end of 1984 show a 31% reduction in mortality from breast cancer and a 25% reduction in the rate of stage II or more advanced breast cancers in the group invited to screening. 7 years after the start of the study the excess of stage I cancers in the study group largely outweighs the deficit of advanced cancers.