Overestimating Overdiagnosis in Breast Cancer Screening

Which type of cancer is detected in breast screening programs? Review of the literature with focus on the most frequent histological features

Breast cancer is the most frequent type of cancer affecting female patients. The introduction of breast cancer screening programs led to a substantial reduction of mortality from breast cancer. Nevertheless, doubts are being raised on the real efficacy of breast screening programs. The aim of the present paper is to review the main pathological type of cancers detected in breast cancer screening programs. Specifically, attention will be given to: in situ carcinoma, invasive carcinoma histotypes and interval cancer.

Patterns of treatment and outcome of ductal carcinoma in situ in the Netherlands

Purpose

To spare DCIS patients from overtreatment, treatment de-escalated over the years. This study evaluates the influence of these developments on the patterns of care in the treatment of DCIS with particular interest in the use of breast conserving surgery (BCS), radiotherapy following BCS and the use and type of axillary staging.

Methods

In this large population-based cohort study all women, aged 50–74 years diagnosed with DCIS from January 1989 until January 2019, were analyzed per two-year cohort.

Results

A total of 30,417 women were diagnosed with DCIS. The proportion of patients undergoing BCS increased from 47.7% in 1995–1996 to 72.7% in 2017–2018 (p < 0.001). Adjuvant radiotherapy following BCS increased from 28.9% (1995–1996) to 89.6% (2011–2012) and subsequently decreased to 74.9% (2017–2018; p < 0.001). Since its introduction, the use of sentinel lymph node biopsy (SLNB) increased to 63.1% in 2013–2014 and subsequently decreased to 52.8% in 2017–2018 (p < 0.001). Axillary surgery is already omitted in 55.8% of the patients undergoing BCS nowadays. The five-year invasive relapse-free survival (iRFS) for BCS with adjuvant radiotherapy in the period 1989–2010, was 98.7% [CI 98.4% – 99.0%], compared to 95.0% [CI 94.1% –95.8%] for BCS only (p < 0.001). In 2011–2018, this was 99.3% [CI 99.1% – 99.5%] and 98.8% [CI 98.2% – 99.4%] respectively (p = 0.01).

Conclusions

This study shows a shift toward less extensive treatment. DCIS is increasingly treated with BCS and less often followed by additional radiotherapy. The absence of radiotherapy still results in excellent iRFS. Axillary surgery is increasingly omitted in DCIS patients.

Higher breast cancer prevalence associated with higher socioeconomic status in the South Korean population; Has it resulted from overdiagnosis?

Recently, breast cancer prevalence has increased in South Korea. In this study, we investigated the correlation between breast cancer prevalence and socioeconomic status. This study enrolled 27,331 people who participated in the Korean National Health and Nutrition Examination Survey (KNHANES) IV–VI (2007–2015). In addition, we obtained data from the Korean Statistical Information Service (KSIS) on the breast cancer age-standardized incidence rate (AIR), the age-standardized mortality rate (AMR), the number of women screened, and the number of newly diagnosed patients. The KHANES data showed that breast cancer prevalence was significantly associated with educational level (odds ratio [OR], 2.02; 95% confidence interval [CI], 1.08–3.77 for 10–12 vs. ≤ 6 years of education, and OR, 2.36; 95% CI, 1.10–5.06 for ≥ 13 vs. ≤ 6 years of education). However, there was no significant association of breast cancer prevalence with monthly household income. In a separate analysis of the AIR, AMR, and number of women screened for breast cancer, the AIR increased with the number of women screened, whereas the AMR did not. Furthermore, the number of newly diagnosed patients in all age groups increased over time. The present results demonstrate that the recently increased breast cancer prevalence documented in South Korea may be attributable to earlier detection rather than to a real increase in prevalence, and that breast cancer may be overdiagnosed.