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Clinical calculator summary

CTS5 Late Recurrence Calculator

CTS5 is a clinicopathologic score estimating late distant recurrence risk from years 5 to 10 in ER-positive early breast cancer after 5 years of endocrine therapy.

Evidence-based context for fast calculator use

Purpose:
Support extended endocrine therapy risk discussion
Population:
Patients with ER-positive early breast cancer who are distant recurrence-free after 5 years of endocrine therapy
Factors:
Age, Tumor size, Tumor grade, Positive lymph nodes
Reference:
Dowsett et al., J Clin Oncol 2018
HomeCTS5 Late Breast Cancer Recurrence
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CTS5 Late Breast Cancer Recurrence

years
mm

Clinical Context & Background

The Clinical Treatment Score post-5 years (CTS5) estimates late distant recurrence risk after 5 years of endocrine therapy using age, invasive tumor size, grade, and involved lymph nodes. It was developed for patients with ER-positive early breast cancer who are distant recurrence-free at 5 years and is most established in postmenopausal populations.
CTS5 can support extended endocrine therapy discussions, but it does not directly predict treatment benefit and should be interpreted alongside menopausal status, toxicity, bone health, genomic assays when available, patient preference, and oncology guideline context.
Primary Source EvidenceDowsett M, Sestak I, Regan MM, et al. Integration of Clinical Variables for the Prediction of Late Distant Recurrence in Patients With Estrogen Receptor-Positive Breast Cancer Treated With 5 Years of Endocrine Therapy: CTS5. J Clin Oncol. 2018;36(19):1941-1948.
Formula Logic
CTS5 = 0.438 x node group + 0.988 x (0.093 x size - 0.001 x size^2 + 0.375 x grade + 0.017 x age). Tumor size is capped at 30 mm; node group maps 0, 1, 2-3, 4-9, >9 positive nodes to 0-4.

Reference Data

CTS5 Score5-10 Year Late Distant Recurrence Category
< 3.13Low risk (<5%)
3.13 - 3.86Intermediate risk (5-10%)
> 3.86High risk (>10%)

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Frequently Asked Questions

Does CTS5 predict benefit from extended endocrine therapy?

CTS5 estimates late distant recurrence risk. It does not directly predict benefit from extended endocrine therapy, so treatment decisions should also consider toxicity, menopausal status, bone health, genomic assays when available, and patient preference.

When should CTS5 be used?

CTS5 is intended for ER-positive early breast cancer patients who have completed 5 years of endocrine therapy without distant recurrence, especially in postmenopausal populations where the model is most established.

Evidence-based oncology decision support. Verify with clinical guidelines.