Steroidogenesis Inhibitors as Second-Line Treatment After TSS, Primary Treatment of Occult/Metastatic EAS, and Adjunctive to Reduce Cortisol in Adrenocortical Carcinoma

STEP 1 — Gather Information

Confirm diagnosis of Cushing’s syndrome (elevated UFC or late‑night salivary cortisol), determine ACTH dependence (measure plasma ACTH), identify etiology (pituitary MRI for CD, chest/abdominal imaging for occult/metastatic EAS, adrenal CT/MRI for ACC), document prior treatments (TSS, radiation/radiosurgery), assess surgical candidacy, and review comorbidities and concomitant medications. Proceed to rule‑in/rule‑out.

STEP 2 — Rule In / Rule Out

Is the patient ACTH‑dependent Cushing’s syndrome (CD or EAS) or adrenal carcinoma (ACC)? If ACTH‑dependent, go to Step 3A; if ACC, go to Step 3B. This binary fork directs the pathway to the appropriate indication.

STEP 3A — Classify or Stratify (ACTH‑dependent)

Classify as either (i) post‑TSS Cushing’s disease (with or without prior RT/radiosurgery) or (ii) occult/metastatic ectopic ACTH syndrome. Endpoint: decide whether steroidogenesis inhibitors are indicated as second‑line after TSS or as primary therapy for EAS.

STEP 3B — Classify or Stratify (Adrenal Carcinoma)

Classify as adrenocortical carcinoma requiring adjunctive cortisol‑lowering therapy. Endpoint: decide to use steroidogenesis inhibitors to reduce cortisol levels in ACC.

STEP 4 — Decide

Initiate a steroidogenesis inhibitor (ketoconazole, metyrapone, or mitotane) according to the specific condition: second‑line after TSS in CD (with or without RT/radiosurgery); primary treatment of occult/metastatic EAS; adjunctive to reduce cortisol in ACC. Titrate dose based on UFC or late‑night salivary cortisol, monitor for adrenal insufficiency and drug interactions, and reassess every 3–6 months.

Clinical Guardrails / Mimics / Pitfalls

Do not use steroidogenesis inhibitors as first‑line when curative surgery is feasible; avoid ketoconazole in severe hepatic impairment or concomitant CYP3A4 substrates without dose adjustment; watch for QT prolongation with metyrapone/mitotane; monitor for adrenal insufficiency (especially with mitotane) and provide stress‑dose glucocorticoids during illness; do not rely solely on hormonal markers for mifepristone‑like agents; avoid in pregnancy unless benefit outweighs risk.

Concrete Clinical Example

A 42‑year‑old woman with persistent Cushing’s disease after TSS (UFC 620 nmol/L, MRI shows 6 mm residual pituitary lesion, not a surgical candidate) is started on ketoconazole 400 mg twice daily. UFC falls to 150 nmol/L after 4 weeks; dose is maintained with monthly UFC and liver‑function checks. She remains eucortisolemic with no adrenal insufficiency after 6 months.

Source: Treatment of Cushing’s Syndrome: An Endocrine Society Clinical Practice Guideline, Endocrine Society, 2015, DOI:10.1210/jc.2015-1818