Based on recommended screening strategies in Western countries (No authors listed 2009; Smith et al. 2003) and screening experiences in other countries (Shetty 2011; Uchida et al. 2008), our current population-based breast cancer screening program conducted in Qibao county of Minhang district in Shanghai, China, was designed to combined use of MAM and US to early detect breast cancer in Chinese women. Considering the large population and limited resources in China, clinical breast examination (CBE) was also used as one of screening methods, which has been suggested as a good candidate for early detecting of breast cancer in developing countries like India and China (Jatoi 2003).
After two rounds of biennial screening, the incidence of breast cancer was much higher in participants than in non-participants. It also appears increase dramatically compared with the age-specific incidence rates in general female population of Shanghai, China (Shanghai Municipal Center for Disease Control and Prevention 2010; Shanghai Municipal Center for Disease Control and Prevention 2011). The incidence pattern by age-groups was greatly changed by the screening program. In non-participants, the incidence remained stable along age with a small peak around 45 years old, which is similar to the patterns observed in Asian women (Lee et al. 2009; Tonelli et al. 2011). In the participants, conversely, the incidence increased with increasing age, which is very close to the patterns in western countries (Lee et al. 2009). Early detection of breast cancer, particularly the 1st round of screening, may be the main reason for the change. That is, some patients who would be diagnosed naturally later were detected ahead, resulting in a temporally elevated incidence rate. However, due to that 2.5% of participants in our population had family history of breast cancer, much higher than 1.4% in the general population of Shanghai (DeRoo et al. 2010), selection bias could not be excluded.
Many factors may influence the accuracy of the screening methods. The performance of CBE mainly depends on the operator’s skills and experience. In this program, the CBE was conducted by several skilled and experienced surgeons, making the overall sensitivity as high as 61.4%. However, the specificity and PPV of CBE were quite lower than other screening methods. MAM alone shows a lower sensitivity in this population than it did in other ethnic populations (Mushlin et al. 1998), possibly due to smaller and denser breasts in Asian women. However, we find that, along with increasing age the sensitivity of MAM increased while that of US decreased, as a result combined use of the two methods greatly improved the overall diagnostic sensitivity, consistently with the findings in communities and in clinical practice (Ji et al. 2013). We also find that the hormone receptor status of breast cancer influence the sensitivity of MAM, but not the accuracy of US, providing further evidence for value of US as complementary tool to MAM in breast cancer screening among Chinese women.
The Qibao screening modality was designed to use different screening methods combinedly and focus on Chinese women possibly at high risk of the disease. Based on the age-specific incidence and age-specific sensitivity of different screening methods in this population, we find that the adjustment in age-group at high risk and the modification of screening methods can save costs for examination without trading off any effectiveness. These results suggest that the Qibao screening modality can be further improved. Cost-effective analysis of the program, however, is warranted to optimize and expand the use of the modality in China.
The strengths of the study included the representative sample of community female residents, large sample size and well-designed screening modality. However, only two rounds of screening have completed, limiting the statistical power in the analysis.
In conclusion, the Qibao modality is an effective strategy for breast cancer screening in Chinese women. The preliminary results of the first two rounds of screening provide implications on how to further improve the effectiveness of screening in Chinese population.