Abstract
PurposeEstimating risk of late distant recurrence (DR) is an important goal for managing women with hormone receptor–positive breast cancer after 5 years of endocrine treatment without recurrence. We developed and validated a simple clinicopathologic tool (Clinical Treatment Score post–5 years [CTS5]) to estimate residual risk of DR after 5 years of endocrine treatment.Patients and MethodsThe ATAC (Arimidex, Tamoxifen, Alone or in Combination) data set (N = 4,735) was used to create a prognostic score for post–5-year risk of DR. Validity of CTS5 (ATAC) was tested in the BIG 1-98 data set (N = 6,711). Time to late DR, 5 years after finishing scheduled endocrine therapy, was the primary end point. Cox regression models estimated the prognostic performance of CTS5 (ATAC).ResultsCTS5 (ATAC) was significantly prognostic for late DR in the ATAC cohort (hazard ratio, 2.47; 95% CI, 2.24 to 2.73; P < .001) and BIG 1-98 validation cohort (hazard ratio, 2.07; 95% CI, 1.88 to 2.28; P < .001). CTS5 (ATAC) risk stratification defined in the training cohort as low (< 5% DR risk, years 5 to 10), intermediate (5% to 10%), or high (> 10%) identified 43% of the validation cohort as low risk, with an observed DR rate of 3.6% (95% CI, 2.7% to 4.9%) during years 5 to 10. From years 5 to 10, 63% of node-negative patients were low risk, with a DR rate of 3.9% (95% CI, 2.9% to 5.3%), and 24% with one to three positive nodes were low risk, with a DR rate of 1.5% (95% CI, 0.5% to 3.8%). A final CTS5 for future use was derived from pooled data from ATAC and BIG 1-98.ConclusionCTS5 is a simple tool based on information that is readily available to all clinicians. CTS5 was validated as highly prognostic for late DR in the independent BIG 1-98 study. The final CTS5 algorithm identified 42% of women with < 1% per-year risk of DR who could be advised of the limited potential value of extended endocrine therapy.
Highlights
Women with estrogen receptor (ER) –positive primary breast cancer are generally offered adjuvant endocrine therapy for 5 years
Clinical Treatment Score post–5 years (CTS5) (ATAC) risk stratification defined in the training cohort as low (, 5% distant recurrence (DR) risk, years 5 to 10), intermediate (5% to 10%), or high (. 10%) identified 43% of the validation cohort as low risk, with an observed DR rate of 3.6% during years 5 to 10
CTS5 is a simple tool based on information that is readily available to all clinicians
Summary
Women with estrogen receptor (ER) –positive primary breast cancer are generally offered adjuvant endocrine therapy for 5 years. 60,000 women with ER-positive disease, who were scheduled to receive 5 years of endocrine therapy and remained disease free at 5 years, reported the subsequent risk of distant recurrence.[9] Even in patients with T1N0 disease, the estimated risk of distant recurrence between years 5 and 20 was 10% for those with low, 13% for those with intermediate, and 17% for those with high histologic grades, respectively. These data unequivocally demonstrate the importance of these clinicopathologic factors, they include studies from 40 years ago, possibly limiting their relevance for contemporary patients with breast cancer. The largely tamoxifen-treated population did not allow assessment of possible differences between tamoxifen and aromatase inhibitors (AIs) with regard to long-term risk
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