Norwegian Institute of Public Health, Nydalen, Oslo, Norway. per-henrik.zahl@fh i.no
Lancet Oncol. 2011 Nov;12(12):1118-24. doi: 10.1016/S1470-2045(11)70250-9. Epub 2011 Oct 11.
The natural history of screen-detected breast cancers is not well understood. A previous analysis of the incidence change during the introduction of the Norwegian screening programme in the late 1990s suggested that the natural history of many screen-detected invasive breast cancers is to regress spontaneously but the study was possibly confounded by use of hormone replacement therapy in the population. We did a similar analysis of data collected during an earlier period when few women were exposed to hormone replacement therapy.
We compared cumulative breast cancer incidence in age-matched cohorts of women living in seven Swedish counties before and after the initiation of public mammography screening between 1986 and 1990. Women aged 40-49 years were invited to screening every year and women aged 50-74 years were invited every 2 years. A screened group including all women aged 40-69 years (n=328,927) was followed-up for 6 years after the first invitation to the programme. A control group including all women in the same age range (n=317,404) was also followed-up for 6 years--4 years without screening and 2 years when they entered the screening programme. Screening attendance was much the same in both groups (close to 80%). Counts of incident invasive breast cancers were obtained from the Swedish Cancer Registry (in-situ cancers were excluded).
Before the age-matched controls were invited to be screened at the end of their follow-up period, the 4-year cumulative incidence of invasive breast cancer was significantly higher in the screened group (982 per 100,000) than it was in the control group (658 per 100,000) (relative risk [RR] 1·49, 95% CI 1·41-1·58). Even after prevalence screening in the control group, the screened group had higher 6-year cumulative incidence of invasive breast cancer (1443 per 100,000 vs 1269 per 100,000; RR 1·14, 1·10-1·18).
Because the cumulative incidence among controls did not reach that of the screened group, we believe that many invasive breast cancers detected by repeated mammography screening do not persist to be detected by screening at the end of 6 years, suggesting that the natural course of many of the screen-detected invasive breast cancers is to spontaneously regress.
None.
对筛检发现的乳腺癌的自然病程尚缺乏了解。对 90 年代末挪威筛检项目引入期间发病率变化的一项既往分析提示，许多筛检发现的浸润性乳腺癌的自然病程是自发消退，但该研究可能因人群中使用激素替代疗法而受到混杂。我们对更早时期的数据进行了类似分析，当时很少有女性接触激素替代疗法。
我们比较了 1986 年至 1990 年期间瑞典七个县公共乳房 X 线摄影筛检启动前后，年龄匹配的队列中妇女的累积乳腺癌发病率。40-49 岁的妇女每年接受筛检，50-74 岁的妇女每 2 年接受筛检。包括所有 40-69 岁妇女的筛检组（n=328927）在首次邀请参加该项目后 6 年进行随访。对照组包括相同年龄范围的所有妇女（n=317404），在无筛检的 4 年和进入筛检项目的 2 年期间进行随访。两组的筛检参与率大致相同（接近 80%）。从瑞典癌症登记处获得浸润性乳腺癌发病例数（原位癌除外）。
在年龄匹配的对照组在随访结束时被邀请接受筛检之前，筛检组的 4 年累积浸润性乳腺癌发病率（982/100000）显著高于对照组（658/100000）（相对危险度[RR] 1.49，95%CI 1.41-1.58）。即使在对照组进行了流行筛检后，筛检组的 6 年累积浸润性乳腺癌发病率仍较高（1443/100000 比 1269/100000；RR 1.14，1.10-1.18）。
由于对照组的累积发病率未达到筛检组的水平，我们认为许多通过重复乳房 X 线摄影筛检发现的浸润性乳腺癌不会持续到 6 年后的筛检中被发现，这表明许多筛检发现的浸润性乳腺癌的自然病程是自发消退。
无。
