Detection of breast cancer is better in centres performing a high volu
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《英国医生杂志》
Canadian research indicates that the overall performance of screening mammography is improved when screening is done in large centres and when, in those centres, mammograms are read by radiologists who interpret a large number of films.
Isabelle Th閎erge and colleagues examined the relation between the volume of screening mammography and rates of detection of breast cancer and of false positive readings in the Quebec breast cancer screening programme (CMAJ 2005;172:195-9). The study looked at data on 307 314 asymptomatic women aged 50 to 69 years who were screened between May 1998 and December 2000. Each screening included four radiographic views. The screening mammograms were interpreted by 275 radiologists working in 68 accredited facilities. The mean annual screening volume was 581 per radiologist and 2279 per facility. The researchers analysed rates of breast cancer detection by comparing the 1709 women whose cancer was detected by screening with a 10% simple random sample (n=30 560) of women without breast cancer. The authors analysed rates of false positive readings by comparing the 3159 women with a false positive reading with the 27 401 other women in the 10% random sample. The total number of false positive readings among the women in the study was 32 229 (10.5%).
The authors reported that the overall trend in the rate of detection of breast cancer according to the size of the facility was significant (P=0.004). For all types of cancer combined, the adjusted rate ratio of detection for facilities performing 4000 or more screenings a year, compared with those performing fewer than 2000, was 1.28 (95% confidence interval 1.07 to 1.52).
Radiologists who read a relatively high number of mammograms and worked in facilities that performed a large number of screenings a year tended to have higher detection rates than radiologists who did fewer readings and worked in facilities performing fewer screenings.
In contrast, the frequency of false positive readings was unrelated to the facility抯 screening volume but was inversely related to the radiologist抯 screening volume: false positive rates decreased with increasing caseload (P value for trend 0.001). This trend was clearer among radiologists who worked in large centres. The adjusted rate ratio for radiologists who read 1500 or more screening mammograms a year, compared with radiologists who read fewer than 250, was 0.53 (95% confidence interval 0.35 to 0.79).
"Our results support the notion that radiologists?and facilities?screening volumes are independently associated with performance and that their effects may be complementary," concluded the authors.
The authors?conclusions must be tempered by context and pragmatics, said Dr Jean Urbain, chief of nuclear medicine at the St Joseph抯 Health Centre, London, Ontario. "The ultimate goal is to decrease the rate of death from breast cancer," said Dr Urbain. "To achieve this goal, a responsible healthcare policy that implements screening mammography programmes must find a careful balance between service provision and availability, qualification of radiologists, achievable standards for mammography quality, and population demographics."(Calgary Barbara Kermode-Scott)
Isabelle Th閎erge and colleagues examined the relation between the volume of screening mammography and rates of detection of breast cancer and of false positive readings in the Quebec breast cancer screening programme (CMAJ 2005;172:195-9). The study looked at data on 307 314 asymptomatic women aged 50 to 69 years who were screened between May 1998 and December 2000. Each screening included four radiographic views. The screening mammograms were interpreted by 275 radiologists working in 68 accredited facilities. The mean annual screening volume was 581 per radiologist and 2279 per facility. The researchers analysed rates of breast cancer detection by comparing the 1709 women whose cancer was detected by screening with a 10% simple random sample (n=30 560) of women without breast cancer. The authors analysed rates of false positive readings by comparing the 3159 women with a false positive reading with the 27 401 other women in the 10% random sample. The total number of false positive readings among the women in the study was 32 229 (10.5%).
The authors reported that the overall trend in the rate of detection of breast cancer according to the size of the facility was significant (P=0.004). For all types of cancer combined, the adjusted rate ratio of detection for facilities performing 4000 or more screenings a year, compared with those performing fewer than 2000, was 1.28 (95% confidence interval 1.07 to 1.52).
Radiologists who read a relatively high number of mammograms and worked in facilities that performed a large number of screenings a year tended to have higher detection rates than radiologists who did fewer readings and worked in facilities performing fewer screenings.
In contrast, the frequency of false positive readings was unrelated to the facility抯 screening volume but was inversely related to the radiologist抯 screening volume: false positive rates decreased with increasing caseload (P value for trend 0.001). This trend was clearer among radiologists who worked in large centres. The adjusted rate ratio for radiologists who read 1500 or more screening mammograms a year, compared with radiologists who read fewer than 250, was 0.53 (95% confidence interval 0.35 to 0.79).
"Our results support the notion that radiologists?and facilities?screening volumes are independently associated with performance and that their effects may be complementary," concluded the authors.
The authors?conclusions must be tempered by context and pragmatics, said Dr Jean Urbain, chief of nuclear medicine at the St Joseph抯 Health Centre, London, Ontario. "The ultimate goal is to decrease the rate of death from breast cancer," said Dr Urbain. "To achieve this goal, a responsible healthcare policy that implements screening mammography programmes must find a careful balance between service provision and availability, qualification of radiologists, achievable standards for mammography quality, and population demographics."(Calgary Barbara Kermode-Scott)