Stopping endocrine therapy is not “failure”—it’s good medicine when biology or tolerance demands it.

Indicators for stopping

  • Radiologic or biochemical progression despite verified suppression.

  • Severe Grade 3–4 toxicity per CTCAE v5.0.

  • Completion of planned adjuvant course (5 or 10 years breast / 2–3 years ADT with RT).

  • Patient-driven cessation for irreversible QoL decline after informed discussion.

De-escalation strategies

  • Intermittent ADT (for prostate): stop when PSA < 0.2 ng/mL × 2, resume at > 4 ng/mL or symptoms. Improves QoL with similar OS if response deep.

  • Extended drug holidays for AIs after 5 years in low-risk breast cancer.

  • SERD continuation until clear radiologic progression; no benefit after.

Post-cessation monitoring

  • PSA q 3 mo for first year then q 6 mo.

  • Estradiol / FSH if ovarian function recovery expected.

  • Bone density re-check 12 mo after stopping AI or ADT.

(Data: PR7 trial, NEJM 2012; SOFT/TEXT trials)

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