Overview of individual estimates of overdiagnosis for invasive breast cancer, excluding cases of carcinoma in situ except for Manitoba, Canada
| Variables | United Kingdom | Manitoba, Canada | New South Wales, Australia | Sweden | Norway (AORH counties) |
|---|---|---|---|---|---|
| Period for estimation of prescreening trend | 1971-84 | 1970-8 | 1972-87 | 1971-85 | 1980-94 |
| Selection method for last prescreening year | Opportunistic screening starts | Opportunistic screening starts | Last year before screening | Last year before screening | Last year before screening |
| Period for estimation of postscreening trend | 1993-9 | 1995-2005 | 1996-2002 | 1998-2006 | 2000-6 |
| Breast cancer incidence in final year of observation (per 100 000 women) | |||||
| Screened age group: | |||||
| Observed (regression analysis) | 278 | 318/375* | 291 | 328 | 303 |
| Expected (regression analysis) | 197 | 236/236* | 211 | 242 | 213 |
| Observed/expected | 1.41 | 1.35/1.59 | 1.38 | 1.35 | 1.42 |
| Exceeded age for screening: | |||||
| Observed (regression analysis) | 278 | 401/442* | 317 | 303 (1998) | 246 |
| Expected (regression analysis) | 277 | 498/522* | 289 | 338 (1998) | 289 |
| Observed/expected | 1.01 | 0.81/0.85 | 1.10 | 0.90 | 0.85 |
| Compensatory drop | No | Yes | No | Yes | Yes |
| Overdiagnosis (%) with CIS | NA | 44 | NA | NA | NA |
| Estimated overdiagnosis (%), assuming 10% CIS | 57 | 53 | 46 | 52 | |
AORH=Akershus, Oslo, Rogaland, and Hordaland; NA=not available; CIS=carcinoma in situ.
*Without/with CIS.