Observer Variability in Breast Cancer Diagnosis between Countries with and without Breast Screening.

RATIONAL AND OBJECTIVES: Image reporting is a vital component of patient management depending on individual radiologists' performance. Our objective was to explore mammographic diagnostic efficacy in a country where breast cancer screening does not exist. MATERIALS AND METHODS: Two mammographic test sets were used: a typical screening (TS) and high-difficulty (HD) test set. Nonscreening (NS) radiologists (n = 11) read both test sets, while 52 and 49 screening radiologists read the TS and HD test sets, respectively. The screening radiologists were classified into two groups: a less experienced (LE) group with ≤5 years' experience and a more experienced (ME) group with ≥5 years' experience. A Kruskal-Wallis and Tukey-Kramer post hoc test were used to compare reading performance among reader groups, and the Wilcoxon matched pairs tests was used to compare TS and ND test sets for the NS radiologists. RESULTS: Across the three reader groups, there were significant differences in case sensitivity (χ2 [2] = 9.4, P = .008), specificity (χ2 [2] = 10.3, P = .006), location sensitivity (χ2 [2] = 19.8, P < .001), receiver operating characteristics, area under the curve (χ2 [2] = 19.7, P < .001) and jack-knife free-response receiver operating characteristics (JAFROCs) (χ2 [2] = 18.1, P < .001). NS performance for all measured scores was significantly lower than those for the ME readers (P < .006), while only location sensitivity was lower (χ2 [2] = 17.5, P = .026) for the NS compared to the LE group. No other significant differences were observed. CONCLUSION: Large variations in mammographic performance exist between radiologists from screening and nonscreening countries.

Mammographic detection of breast cancer in a non-screening country.

OBJECTIVE:: To compare the diagnostic accuracy between radiologists' from a country with and without breast cancer screening. METHODS:: All participating radiologists gave informed consent. A test-set involving 60 mammographic cases (20 cancer and 40 non-cancer) were read by 11 radiologists from a non-screening (NS) country during a workshop in July 2016. 52 radiologists from a screening country read the same test-set at the Royal Australian and New Zealand College of Radiologists' meetings in July 2015. The screening radiologists were classified into two groups: those with less than or equal to 5 years of experience; those with more than 5 years of experience, and each group was compared to the group of NS radiologists. A Kruskal-Wallis test followed by post-hoc multiple comparisons test were used to compare measures of diagnostic accuracy among the reader groups. RESULTS:: The diagnostic accuracy of the NS radiologists was significantly lower in terms of sensitivity [mean = 54.0; 95% confidence interval (CI) (40.0-67.0)], location sensitivity [mean = 26.0; 95% CI (16.0-37.0)], receive roperating characteristic area under curve [mean = 73.0; 95% CI (66.5-81.0)] and Jackknifefree-response receiver operating characteristics figure-of-merit [mean = 45.0; 95% CI (40.0-50.0)] when compared with the less and more experienced screening radiologists, whilst no difference in specificity [mean = 75.0; 95% CI (70.0- 81.0)] was found. No significant differences in all measured diagnostic accuracy were found between the two groups of screening radiologists. CONCLUSION:: The mammographic performance of a group of radiologists from a country without screening program was suboptimal compared with radiologists from Australia. ADVANCES IN KNOWLEDGE:: Identifying mammographic performance in developing countries is required to optimize breast cancer diagnosis.