Abstract
BackgroundManagement advice for women with lobular carcinoma in situ (LCIS) is hampered by the lack of accurate personalised risk estimates for subsequent invasive breast cancer (BC). Prospective validation of the only tool that estimates individual BC risk for a woman with LCIS, the International Breast Cancer Intervention Study Risk Evaluation Tool (IBIS-RET), is lacking.MethodsUsing population-based cancer registry data for 732 women with LCIS, the calibration and discrimination accuracy of IBIS-RET Version 7.2 were assessed.ResultsThe mean observed 10-year risk of invasive BC was 14.1% (95% CI:11.3%-17.5%). IBIS-RET overestimated invasive BC risk (p = 0.0003) and demonstrated poor discriminatory accuracy (AUC 0.54, 95% CI: 0.48 – 0.62).ConclusionsClinicians should understand that IBIS-RET Version 7.2 may overestimate 10-year invasive BC risk for Australian women with LCIS. The newer IBIS-RET Version 8.0, released September 2017, includes mammographic density and may perform better, but validation is needed.
Highlights
Women diagnosed with lobular carcinoma in-situ (LCIS) have an elevated risk of subsequent invasive breast cancer (BC)[1] that increases by about 1% every year after diagnosis to 13% after 10 years, 11%-26% at 15 years[1,2,3] and 21%-26% risk after 20 years.[4, 5]
Most are managed with observation alone,[6] but American Society of Clinical Oncology and Cancer Australia guidelines recommend that risk-reducing medications, selective oestrogen receptor modulators (SERM) or aromatase inhibitors (AI), be discussed with lobular carcinoma in situ (LCIS) patients.[7,8,9,10]
There were 732 eligible women, of whom 73 were diagnosed with invasive BC within 10 years after their LCIS. 10 women died within 10 years without an invasive BC diagnosis, 293 women were invasive BC-free at 10 years and 356 women were last observed without invasive BC with less than 10 years follow-up
Summary
Women diagnosed with lobular carcinoma in-situ (LCIS) have an elevated risk of subsequent invasive breast cancer (BC)[1] that increases by about 1% every year after diagnosis to 13% after 10 years, 11%-26% at 15 years[1,2,3] and 21%-26% risk after 20 years.[4, 5]Most are managed with observation alone,[6] but American Society of Clinical Oncology and Cancer Australia guidelines recommend that risk-reducing medications, selective oestrogen receptor modulators (SERM) or aromatase inhibitors (AI) (the latter only in postmenopausal women), be discussed with LCIS patients.[7,8,9,10] Risk-reducing bilateral mastectomy is pursued by only a minority of LCIS patients.[11]. The International Breast Cancer Intervention Study Risk Evaluation Tool (IBIS-RET) is the only tool available to estimate risk for an individual woman with LCIS. Using population-based data, we prospectively examined the performance of IBIS-RET Version 7.2 for estimating invasive BC risk for women with a history of LCIS. Management advice for women with lobular carcinoma in situ (LCIS) is hampered by the lack of accurate personalised risk estimates for subsequent invasive breast cancer (BC). Prospective validation of the only tool that estimates individual BC risk for a woman with LCIS, the International Breast Cancer Intervention Study Risk Evaluation Tool (IBIS-RET), is lacking. METHODS: Using population-based cancer registry data for 732 women with LCIS, the calibration and discrimination accuracy of IBIS-RET Version 7.2 were assessed. CONCLUSIONS: Clinicians should understand that IBIS-RET Version 7.2 may overestimate 10-year invasive BC risk for Australian women with LCIS. The newer IBIS-RET Version 8.0, released September 2017, includes mammographic density and may perform better, but validation is needed
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