A simple way to measure the burden of interval cancers in breast cancer screening

Abstract

BackgroundThe sensitivity of a mammography program is normally evaluated by comparing the interval cancer rate to the expected breast cancer incidence without screening, i.e. the proportional interval cancer rate (PICR). The expected breast cancer incidence in absence of screening is, however, difficult to estimate when a program has been running for some time. As an alternative to the PICR we propose the interval cancer ratio . We validated this simple measure by comparing it with the traditionally used PICR.MethodWe undertook a systematic review and included studies: 1) covering a service screening program, 2) women aged 50-69 years, 3) observed data, 4) interval cancers, women screened, or interval cancer rate, screen detected cases, or screen detection rate, and 5) estimated breast cancer incidence rate of background population. This resulted in 5 papers describing 12 mammography screening programs.ResultsCovering initial screens only, the ICR varied from 0.10 to 0.28 while the PICR varied from 0.22 to 0.51. For subsequent screens only, the ICR varied from 0.22 to 0.37 and the PICR from 0.28 to 0.51. There was a strong positive correlation between the ICR and the PICR for initial screens (r = 0.81), but less so for subsequent screens (r = 0.65).ConclusionThis alternate measure seems to capture the burden of interval cancers just as well as the traditional PICR, without need for the increasingly difficult estimation of background incidence, making it a more accessible tool when evaluating mammography screening program performance.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2407-14-782) contains supplementary material, which is available to authorized users.

Breast Cancer Screening Program in Lithuania: Interval Cancers and Program Sensitivity After 7 Years of Mammography Screening

“…Usually, the number of screen-detected cancers is higher in initial screens than in subsequent ones 10,28 ; however, it was not the case in our program. The number of screen-detected cancers was lower in the first screening years than in later ones.…”

“…Andersen with colleagues 10 conducted a systematic review of 12 screening programs in Europe and counted ICR for initial and subsequent screening rounds. The ICR varied from 0.10 to 0.28 covering initial screens only.…”

Atrankinės Mamografinės Patikros Vykdymo Patirtis Nacionaliniame Vėžio Institute

“…Intervaliniais navikais laikyti piktybiniai navikai, nustatyti 0-730 dienų laikotarpiu (vieno patikros ciklo laikotarpis) po mamogramos atlikimo, jei mamogramoje nepamatyta jokių pokyčių arba pastebėti pokyčiai vertinti kaip gerybiniai arba galbūt gerybiniai (BIRADS 1, 2 ir 3). Jų dažnis skaičiuotas pagal Andersen su bendraautoriais pasiūlytą metodiką [11]. Atrinkus intervalinius navikus, vertintas jų skaičius, stadija, ryšys su BIRADS kategorija bei krūties audinio tankumu.…”

“…Tačiau toks metodas yra gana sudėtingas ir kai kurių autorių kritikuojamas, kadangi atrankinė mamografinė patikra vykdoma jau daug metų daugelyje šalių ir tikėtiną bazinį sergamumą, jei tokia programa nevykdoma, sunku apskaičiuoti. Tyrėjai iš Danijos [11] pasiūlė paprastesnę intervalinių navikų dažnio apskaičiavimo formulę:…”

Longitudinal fluctuation in mammographic percent density differentiates between interval and screen‐detected breast cancer

“…IC is defined as breast cancer that is detected after a negative screen but before the next regular visit or end of a normal screening interval––which in Sweden has a length of 18–24 months depending on age and county. In a review of 10 different studies, most of them Scandinavian, the proportion of ICs was 22%–37% in the regularly screened women …”