Stage migration due to introduction of the sentinel node procedure: a population-based study

Abstract

International audienceIntroduction of sentinel node biopsy (SNB) as an axillary staging procedure in breast cancer patients could have led to upstaging as well as downstaging of their disease. Intensified pathological processing could have led to upstaging due to presence of micrometastases, whereas the described false negative rate of 5% could be a cause of downstaging. We investigated whether or not the introduction of the sentinel node procedure has changed the incidence of axillary nodal micrometastases and induced stage migration on a population based level. Data from the population based Eindhoven Cancer Registry were used on all ( = 17100) women diagnosed with invasive breast cancer in the South-East region of The Netherlands in the period 1994–2005. The percentage of patients staged with SNB increased from 0% in 1994 to 62% in 2005. The percentage of patients with micrometastases increased from 1.0% in 1994 to 4.3% in 2005 ( < 0.0001), whereas no significant increase was observed of the proportion of patients with positive axillary lymph nodes. After adjustment for tumor size, age at diagnosis and histology the probability of having a positive axillary lymph node status was 10% higher in period 2003–2005, as compared to period 1994–1996. Furthermore, women diagnosed in the period 2003–2005 had a 3.5 times higher risk of having micrometastases compared to women diagnosed in the period 1994–1996 (i.e., before the introduction of SNB). The introduction of SNB in the Southeast region of The Netherlands has led to stage migration, as is reflected by the small but significant increase of the proportion of patients with positive axillary lymph nodes after adjustment for tumor size and age

The impact of mammography screening programmes on incidence of advanced breast cancer in Europe: a literature review

“…Many of the problems also arise from the reliability and validity of incidence data, in particular the unavailability of reliable reference incidence rates for advanced cancer, especially in a historical comparison period, together with the sharp decrease in the proportion of unknown-stage cancers following the introduction of screening. Stage migration bias, caused by the implementation of sentinel lymph node biopsy between the mid-1990s and mid-2000s [18, 19], will also have had an impact.…”

“…Theoretically, the benefit of screening is limited to screen-detected cases, either earlier within the same stage or at an earlier stage. However, using stage in itself has a disadvantage due to the stage migration bias caused by the introduction of sentinel lymph node dissection [18] and by changes in coding and classification practices [19]. In this respect, using only the pT information as a proxy for the diameter of the lesion is the most direct link to radiological detection and less influenced by trends in missing data and changes in coding and classification practices, even though it cannot show within-stage shifts in diameter.…”

“…The pT information alone, which is the most available one, is direct and relatively unaffected by biases due to confounding. Conversely, multiple-stage data are more meaningful, since the effect of screening may differ across different categories of advanced cancers.All studies8Stage migrationThe introduction of sentinel lymph node biopsy between mid-1990s and mid-2000s caused a substantial increase in the registered incidence of node-positive breast cancer (stage migration bias) [18]. The use of pN staging is problematic in studies of trends in ABCR over the last two decades, since changes in the risk of node-positive cancer cannot be adjusted for stage migration.…”

Prognostic impact of isolated tumor cells in breast cancer axillary nodes: single tumor cell(s) versus tumor cell cluster(s) and microanatomic location

“…In eight studies, the presence of isolated tumor cells did not seem to influence prognosis [16][17][18][19][21][22][23][24]. In one of these, however, overall survival was lower in patients who had not undergone an additional axillary lymph node dissection as compared with patients who had undergone an axillary lymph node dissection (P = 0.02) [17].…”

“…Only four studies corrected for use of adjuvant systemic therapy in multivariate analysis [2,19,21]. In eight studies, the presence of isolated tumor cells did not seem to influence prognosis [16][17][18][19][21][22][23][24].…”