Detection Of Small Invasive Cancers Research Articles

Overcoming the limitations of screening mammography in Japan and Korea: a paradigm shift to personalized breast cancer screening based on ultrasonography.

Screening mammography programs have been implemented in numerous Western countries with the aim of reducing breast cancer mortality. However, despite over 20 years of population-based screening mammography, the mortality rates in Japan and Korea continue to rise. This may be due to the fact that screening mammography is not as effective for Japanese and Korean women, who often have dense breasts. This density decreases the sensitivity of mammography due to a masking effect. Therefore, the early detection of small invasive cancers requires more than just mammography, particularly for women in their 40s. This review discusses the limitations and challenges of screening mammography, as well as the keys to successful population-based breast cancer screening in Japan and Korea. This includes a focus on breast ultrasonography techniques, which are based on histopathologic anatomical knowledge, and personalized screening strategies that are based on risk assessments measured by glandular tissue components.

Ductal carcinoma in situ (DCIS): are we overdetecting it?

DCIS constitutes approximately one-quarter of screen-detected cancer. The proportion of screen-detected cancer that is DCIS decreases with the age of the screening population. Whether detecting DCIS at mammographic screening is of benefit depends on the natural history of the DCIS detected at screening and whether DCIS detection enables the detection of invasive foci already present within DCIS lesions. The natural history of DCIS varies according to the grade of the DCIS detected. The natural history of low grade DCIS is that approximately 60% of lesions will become invasive at 40 years follow-up. The natural history of high grade DCIS derived from local recurrence rates within high grade DCIS lesions, which have been inadequately resected and not given radiotherapy, suggests an invasive risk of at least 50% at 7 years follow-up. Given the average life expectancy of women with screen-detected DCIS is 25 years, this suggests high grade DCIS is an obligate precursor of invasive disease. There is a strong correlation between the grading of invasive cancer and the grade of DCIS from which it arose. This suggests that approximately 50% of low grade DCIS detected at screening will represent overdiagnosis while overdiagnosis of high grade DCIS would be rare. The natural history of intermediate grade DCIS is as yet unknown. Only 15% of screen-detected DCIS is low grade, suggesting that overdiagnosis is uncommon. Approximately 60% of screen-detected DCIS is high grade and in the vast majority of these patients adequate treatment will be preventing the occurrence of high grade invasive breast cancer. Approximately one-third of malignant calcification clusters detected at screening mammography already has an invasive focus. These invasive foci are usually small and high grade. Data gathered from all the units in the National Health Service Breast Screening Programme indicate a strong correlation between the detection of DCIS and the detection of small invasive cancers. These data indicate that for every two cases of DCIS detected, one case of a small invasive cancer is also detected. These data indicate that DCIS detection within a mammographic screening programme prevents the occurrence of high grade invasive cancer and aides the detection of small invasive cancers at a size where treatment can be successful. Overdiagnosis will occur in approximately one-half of the cases of low grade DCIS detected. This represents approximately 2% of screen-detected lesions. If one assumes the natural history of intermediate grade DCIS is intermediate between low and high grade disease then overdiagnosis of DCIS within a screening programme may represent 3% of screen-detected lesions.

Contribution of clinical breast examination to mammography screening in the early detection of breast cancer.

As the benefit of clinical breast examination (CBE) over that of screening mammography alone in reducing breast cancer mortality is uncertain, it is informative to monitor its contribution to interim measures of effectiveness of a screening programme. Here, the contribution of CBE to screening mammography in the early detection of breast cancer was evaluated. Four Canadian organised breast cancer screening programmes. Women aged 50-69 receiving dual screening (CBE and mammography) (n = 300,303) between 1996 and 1998 were followed up between screen and diagnosis. Outcomes assessed by mode of detection (CBE alone, mammography alone, or both CBE and mammography) included referral rate, positive predictive value, pathological features of tumours (size, nodal status, morphology), and cancer detection rates overall and for small cancers (< or = 10 mm or node-negative). Heterogeneity in findings across programmes was also assessed. On first versus subsequent screen, CBE alone resulted in 28.5-36.7% of referrals, and 4.6-5.9% of cancers compared with 52.6-60.1% of referrals and 60.0-64.3% of cancers for mammography alone. Among cancers detected by CBE, 83.6-88.6% were also detected by mammography, whereas for mammographically detected cancers only 31.7-37.2% were also detected by CBE. On average, CBE increased the rate of detection of small invasive cancers by 2-6% over rates if mammography was the sole detection method. Without CBE, programmes would be missing three cancers for every 10,000 screens and 3-10 small invasive cancers in every 100,000 screens. Inclusion of CBE in an organised programme contributes minimally to early detection.

Should Breast Screening Programmes Limit their Detection of Ductal Carcinoma In Situ?

OBJECTIVE: Previous research has shown that the detection of ductal carcinoma in situ (DCIS) aids the detection of small invasive cancers at mammographic screening. A correlation may therefore exist between a screening unit's DCIS detection rate and their small invasive cancer detection rate. We have therefore investigated the effect of DCIS detection rate on the detection of small (<15mm) invasive cancers in the 95 units of the U.K. NHS Breast Screening Programme (NHSBSP). MATERIALS AND METHODS: DCIS detection rates were examined against large (⩾15mm) and small (<15mm) invasive cancer detection rates in women aged 50–64 years at prevalent and incident screens over a 3-year period. RESULTS: After adjusting for background incidence, screening units with the highest DCIS detection of ⩾1.3/1000 detected over 20% more small invasive cancers than units with DCIS detection rates within the NHSBSP guidelines of 0.5–1/1000 (P<0.001). Sixty percent of units had DCIS detection rates above the guidelines. There was no correlation between DCIS detection and ⩾15mm invasive cancer detection. The results suggest that over the range of DCIS rates studied, that for every two extra DCIS cancers detected, an additional small invasive cancer (<15mm) is detected that may otherwise not have been. The results therefore provide supporting evidence that the detection of DCIS aids the detection of small invasive cancers. CONCLUSION: Units with DCIS detection above the NHSBSP guidelines have significantly better small invasive cancer detection rates. The existence of an upper limit for DCIS detection within the NHSBSP may be preventing the detection of small invasive cancers, because units are not recalling some small clusters of calcification in order to keep DCIS detection rates down. The upper limit may therefore be inappropriate. Evans, A. J. and Blanks, R. G. (2002). Clinical Radiology57, 1086–1089.

Axillary Lymph Node Dissection in Breast Cancer: Current Status and Controversies, Alternative Strategies and Future Perspectives

Axillary lymph node dissection (ALND) has traditionally been considered as a standard procedure in the surgical management of patients with breast cancer. The goals of ALND in breast cancer surgery are: (a) to provide accurate prognostic information, (b) to maintain local control of the disease in the axilla and (c) to provide a rational basis for decisions about adjuvant therapy. Although controversial, ALND may also be associated with a small therapeutic benefit. Recently, the question of whether ALND is needed for every patient with invasive breast cancer has been the subject of ongoing debate in the literature. This is mainly due to the widespread use of adjuvant systemic therapy for patients with node-negative breast cancer and to the increasingly frequent detection of small invasive cancers by mammographic screening; the majority of these patients have negative axillae. Sentinel lymph node (SLN) biopsy is a new, promising, minimally invasive procedure, which accurately predicts nodal status with minimal morbidity, and reserves ALND for patients with positive SLN biopsies. However, this method is still investigational. Partial (levels I and II) ALND remains the gold standard in the surgical management of patients with breast cancer.

Observer variability in cancer detection during routine repeat (incident) mammographic screening in a study of two versus one view mammography.

To examine the reasons for observer variability of cancer detection using one and two view mammography at incident (subsequent) screening and determine whether false negative results (non-recall of a cancer) are due to failure to detect the associated features(s) of the cancer on the mammogram, or misinterpretation of the observed feature(s) as not indicative of malignancy. A random selection of cancers (invasive and in situ) seen as incident cases during the second screening round (January 1994-January 1997) in the South West London Breast Screening Service were used. This service uses two view mammography and double reading with arbitration by a third or further readers for all screens. Mammograms of cases were mixed with those of controls in a 1:2 ratio in two test sets. Eleven experienced film readers, each reading both test sets, took part in the study. Initially the oblique view only was read, then, additionally, the craniocaudal view. Previous films were available to the readers. Data on abnormalities noted on the films and probability of recall were recorded and analysed. 387 valid readings of 36 cancers (30 invasive and six ductal carcinoma in situ) were made by 11 readers. The overall sensitivity increased from 79% with one view to 85% with two views. For invasive cancers < 10 mm the sensitivity was 71% with one view, but increased to 85% with two views. Recall of individual cancers by the readers varied substantially. With one view 15 (50%) of the 30 invasive cancers were recalled by all 11 readers, increasing to 18 (60%) with two views. Of the invasive cancers not recalled by all 11 readers, there was considerable disagreement, particularly for the smaller cancers. With one view 69% of invasive cancers < 10 mm were correctly marked on the proforma compared with 87% with two views. Invasive cancers > 10 mm were almost all marked on the proforma with one or two views. For invasive cancers, the misinterpreted feature that did not lead to recall was most commonly an asymmetry (42%), whereas for in situ cancers it was calcifications (67%). The finding of an irregular mass was the least misinterpreted feature. The study showed that of those invasive cancers detected at routine repeat screening by a programme using two view mammography and double reading with arbitration, at least 50% could be described as "difficult" (for example, "minimal" signs) to recall using the single reading of one view, even under "favourable" study conditions with two normal subjects per case. The finding that at least 87% of invasive cancers < 10 mm are detected (marked on the proforma) with two views, but only 69% with the one view, suggests that for single reading of mammograms with one view the detection of small invasive cancers is a major problem. This problem is helped by the second view. For invasive cancers > or = 10 mm, interpretation (benign or malignant) rather than detection (under these study conditions) was the major cause of recall failure. The most common signs to be misinterpreted were calcifications and asymmetries; once visualised an irregular mass was least likely to be misinterpreted. This study provides evidence that detection and interpretation of most invasive cancers is improved by increasing the number of views, and by increasing the number of readers.

Results from the NHS breast screening programme 1990-1993.

To present results from the NHS breast screening programme (NHSBSP) for the three year period 1990 to 1993, and to examine the extent to which interim targets are being met. Data have been collated from all screening programmes in the United Kingdom on standard "Korner" returns, supplemented for the year 1991/92 by data from the radiology quality assurance programme. Most of the data refer to the prevalent screening round, but some data on rescreening are also available. The total cancer detection rate at prevalent screens was 6.0/1000, 18% being in situ cancers; the detection rate of invasive cancers < or = 10 mm in diameter was 1.3/1000, but data on size were missing for 12% of cancers. Referral rates were significantly lower for programmes using two view mammography at the prevalent screen than for those using single view, and cancer detection rates were significantly higher. For prevalent screens over the three year period, 70% of programmes had a referral rate of < or = 7%, 87% had a benign biopsy rate of < or = 5/1000, and 79% had a cancer detection rate of > or = 5/1000. By contrast, only 30% of programmes appeared to meet the target detection rate of > 1.5/1000 for invasive cancers < or = 10 mm in diameter. While the majority of interim targets are being met by the NHSBSP, the rate of detection of small invasive cancers requires careful monitoring. Collection of more accurate data on size of cancers and interval cancer rates will give a better indication of progress towards the target mortality reduction.

Mammographic film density and detection of small breast cancers

From its inception, the UK National Breast Screening Programme (NHSBSP) has recognized that optimum image quality of the mammographic screening test is a key objective. The overall optical density of the mammography film is one of the factors expected to have a significant effect on the image quality of the mammogram with the potential to influence cancer detection. In a previous review of the performance of mammography equipment in the NHSBSP, it was observed that there was a very wide range in the mammographic film densities used at different breast screening centres. In this study a mammography test object was used to show experimentally that, for a typical mammography system, image quality increased substantially with increased film density. Summary data was therefore requested from radiologists in the NHSBSP on the rate of detection of small invasive cancers (diam. < or = 10 mm) and the typical film density used during that year. Proforma were completed for 61 annual sets of results from 31 screening centres involving over 500,000 women. Where centres reported using film densities of less than 1.2D the average small cancer detection rate was 0.12% +/- 0.01%, as compared to an average of 0.17% +/- 0.01% for centres using higher film densities. The results indicate that there is a need for national guidelines in the setting of film densities, and a range for target film densities of 1.4D to 1.8D has been suggested. Attention to optimizing image quality by increasing film density is of particular importance to any screening centre where film densities of less than 1.2D are used, as there may be the potential to increase the detection of small breast cancers by as much as 50%.