Effect of false-positive screening mammograms on rescreening in Western Australia.

OBJECTIVES: To quantify the effect of previous false-positive mammogram results on rescreening rates in a population of women participating in the BreastScreen WA (BSWA) program. DESIGN AND PARTICIPANTS: Retrospective cohort study of women aged 50-69 years who received free screening mammograms at BSWA between 1 January 1995 and 31 December 2007. MAIN OUTCOME MEASURES: Percentages of women attending rescreening, and risk ratios for rescreening. RESULTS: A total of 22 396 screening mammograms were falsely reported as positive, and 560 333 mammogram screens were reported as normal (negative). Women with a false-positive index mammogram result were less likely than women with a true-negative index mammogram result to attend rescreening at 27 months (67.6% v 70.7%; risk ratio, 0.96; P < 0.001). A reduced rescreening rate was seen in all subgroups of women except Indigenous women. Rescreening rates were affected by the types of assessment done at the recall visit. CONCLUSION: Mammographic population screening services should keep their false-positive result rates low, to prevent women from being deterred from screening.

BreastScreen-based mammography screening in women with a personal history of breast cancer, Western Australian study.

OBJECTIVE: To evaluate mammography screening outcomes in women with a personal history of breast cancer (PHBC), who have an increased risk of recurrent or new breast cancer, relative to women without PHBC. DESIGN, SETTING AND PARTICIPANTS: Retrospective study of 713,191 screening mammograms from two groups of women - those with versus those without PHBC - who participated in the BreastScreen WA program in Western Australia between 1997 and 2006. MAIN OUTCOME MEASURES: Cancer detection rate (CDR), recall to assessment rate, recall positive predictive value (PPV) for cancer, and distribution of cancer characteristics within and between the two groups. RESULTS: Screening detected 4125 breast cancers: CDR per 10,000 screens was significantly higher in women with PHBC (95.5; 95% CI, 78.3-112.7) than in women without PHBC (57.2; 95% CI, 55.4-58.9). Recall to assessment rate per 10,000 screens was lower in women with PHBC (385.2; 95% CI, 350.6-419.8) than in women without PHBC (504.9; 95% CI, 499.7-510.2). Recall PPV was higher for women with PHBC (24.8%; 95% CI, 21.0%-28.9%) than those without PHBC (11.2%; 95% CI, 10.9%-11.6%). Cancer characteristics were consistent with early detection (most were smaller than 2 cm and node-negative) and were similarly distributed in both groups, except for tumour grade, with PHBC women having fewer low-grade cancers and slightly more high-grade cancers than women without PHBC. CONCLUSIONS: The relative rate of cancer detection between women with PHBC and women without PHBC who attended an Australian population-based breast screening program was similar to estimates from international studies. Recall rates were within national standards. Screen-detected cancers had similar characteristics in both groups, except for tumour grade. These data support national integration of mammography screening for women with PHBC into BreastScreen, although evaluation of interval cancers will be necessary.

Suspicious mammographic parenchymal abnormalities that are occult at ultrasonography.

AIM: The study aims to ascertain the significance of ultrasonically occult but mammographically suspicious parenchymal abnormalities, detected at screening mammography. METHOD: A retrospective analysis was made on BreastScreen Western Australia data from January 2004 to December 2009. The study group included cases with a mammographic parenchymal abnormality, a negative ultrasound scan and a biopsy under stereotactic guidance. A comparable group of ultrasonically visible carcinomas was used as the control to compare with breast carcinomas in the study sample. RESULTS: Study population consisted of 469 cases. Twenty per cent (n = 92) of the cases were breast carcinomas, with invasive ductal carcinoma (non-specified) being the most common histological type. There was a statistically significant increase in ductal carcinoma in situ and mucinous carcinoma within this malignant subgroup. Three per cent (n = 17) of the total cohort were borderline lesions on histology. The other 77% (n = 360) of cases were benign histology on core biopsy; however, one was subsequently diagnosed as an interval breast carcinoma. CONCLUSION: Stereotactic-guided core biopsy of a suspicious mammographic parenchymal abnormality is warranted, regardless of a normal ultrasound scan, as up to 20% of these cases could be breast carcinomas.

Is Step Down Assessment of screen-detected lesions as safe as workup at a metropolitan assessment centre?

OBJECTIVE: BreastScreen WA offers population mammographic screening via fixed clinics in the metropolitan area and mobile clinics that visit country areas every two years. If an abnormality is suspected following mobile clinic screening, women undergo Step Down Assessment; diagnostic further views are performed at the mobile clinic and if a possibly significant abnormality persists, country women are referred to a Perth Metropolitan Breast Assessment Centre. The purpose of this retrospective cohort study was to determine if Step Down Assessment in country Western Australia offered the same diagnostic effectiveness as screening and assessment in the metropolitan area. METHODS: The study included all screening episodes at BreastScreen WA between 1999 and 2008. Screening episodes from metropolitan and mobile clinics were compared according to the primary outcomes of cancer detection rates, recall and further investigations, cancer size, return to screen rates and interval cancers. RESULTS: Cancer detection rate per 1,000 screening episodes was lower for the country program than the metropolitan program (3.07 (2.84-3.31) versus 7.04 (6.82-7.27)). The false negative (interval cancer) rate was lower for Step Down Assessment than for the metropolitan program. The size of cancers detected was similar for both screening services. Return to screen rates were comparable between both groups. CONCLUSION: The results indicate that the current service model is providing appropriate diagnostic effectiveness, as well as comparable client satisfaction, for country and metropolitan women.

Outcome of mammography in women with large breasts.

UNLABELLED: Mammography has been established as an effective screening tool for the early detection of breast cancer. Obesity may lead to increased breast size and has been linked to increased rates of breast cancer. As women with larger breasts may be predisposed to developing cancer, it is important that mammography is an appropriate test in these women. This study investigated the sensitivity and specificity of mammography in women with larger breasts in a population screening program. METHOD: Data was obtained from 848,648 eligible screening episodes of women aged over 40. Of these episodes, 758,860 were eligible for the study, with 7.2% (54,879 screens) deemed to have large breasts. Large breasts were defined as those for whom at least one large cassette was used in the mammographic process. Those women having only four standard cassettes per screen were classified as having average size breasts (703,981 screens, 92.8%). Cancer detection rates, interval cancer rates (false negatives) and recall to assessment rates were compared for women examined on standard sized cassettes versus large cassettes. Chance corrected measures of sensitivity and specificity and 95% confidence intervals (CI) were calculated for women with and without large breasts. RESULTS: The study found that the sensitivity and specificity of mammography was greater for larger breasted woman. The incidence of breast cancer was also found to be higher in woman with larger breasts in the combined population (73.1 per 100,000 (95% CI 65.9-80.2) in large breasted women versus 52.8 (95% CI 51.1-54.5) in other women) and in each of the specific age groups. This study confirms the appropriateness of mammographic screening for women with large breasts.