Cushing Syndrome and Small-Cell Lung Cancer

Medically Reviewed by Jennifer Robinson, MD on August 05, 2022
4 min read

Cushing syndrome happens when your body has too much of the hormone cortisol. The most common way people get Cushing syndrome is from taking too many steroids called glucocorticoids. But the condition also can happen if your body makes too much cortisol for other reasons, such as small-cell lung cancer (SCLC).

SCLC starts in your lungs’ neuroendocrine cells. These cells act like nerve cells in some ways. But they also can make hormones, including glucocorticoids. When your body is exposed to constant hormones made by a tumor that started in your lungs, you can form Cushing syndrome.

Most people with SCLC won’t get Cushing syndrome. Only about 1% to 5% do. Cushing syndrome caused by lung tumors is known as ectopic Cushing syndrome (ECS). Up to 20% of ECS cases happen because of SCLC. Cushing syndrome can happen more often from another type of lung tumor called a carcinoid tumor.

Symptoms of Cushing syndrome depend on how high the cortisol levels in your body are. They may include:

  • Weight gain
  • Fatty tissue in your middle, upper back, face, or between your shoulders
  • Thin and easily bruised skin
  • Trouble healing after cuts, bug bites, or infections
  • Acne or skin infections
  • Fatigue
  • Weakness
  • Depression or anxiety
  • Trouble controlling emotions
  • Trouble thinking
  • High blood pressure
  • Headache
  • Infection
  • Dark skin or purple marks on your skin
  • Bone loss or fractures
  • Thirst
  • Peeing more

Women with Cushing syndrome may notice more hair growth on their bodies. Their periods may stop or get less regular. Men may have less interest in sex, low fertility, and erectile dysfunction.

There’s not much information about Cushing syndrome specifically in people with SCLC. A lot of what’s known comes from case reports describing individual people with SCLC and Cushing syndrome. Ectopic Cushing syndrome (ECS) tends to be less severe than “classic Cushing syndrome” that’s caused by taking too much steroid medicine. But your symptoms will depend on how high your cortisol hormones are. ECS more often comes with higher blood pressure and lower levels of potassium in your bloodstream. SCLC may cause you to lose weight instead of gain weight.

Cushing syndrome in SCLC is hard for doctors to catch. One reason is that it’s rare. You’ll also have symptoms related to the cancer itself. You might find out you have Cushing syndrome when you find out you have SCLC or even before you have a lung cancer diagnosis. It’s more often diagnosed when cancer comes back after treatment. Sometimes Cushing syndrome starts during chemotherapy.

ECS often doesn’t have all the classic signs of Cushing syndrome either. Sometimes the tumor that's causing it is hard to find. Because of these reasons, it's harder for doctors to diagnose.

Doctors can confirm Cushing syndrome in SCLC based on:

  • High cortisol levels in your blood or pee
  • Ruling out other causes of Cushing syndrome
  • Looking at your tumor tissue after it’s removed to show it’s making cortisol
  • Noting that signs of Cushing syndrome got somewhat better after chemotherapy

Doctors also may use a test called a dexamethasone suppression test. This test measures whether another hormone lowers the amount of cortisol your body is making.

Your doctor may give you medicine to lower your cortisol levels. These medicines may include:

  • Etomidate
  • Ketoconazole
  • Metyrapone
  • Mifepristone
  • Mitotane

It’s best to remove the tumor. But this often isn’t possible if it has already spread. Chemotherapy to fight the cancer also may help. Reports suggest that people with SCLC and Cushing syndrome live longer when they get their cortisol levels down. You could take multiple medicines if one doesn’t work. Your doctor might treat you to lower your cortisol before you start chemotherapy.

SCLC itself is hard to treat. And when you have ECS with SCLC, it usually means:

  • Your lung cancer is advanced.
  • Your lung cancer isn’t responding well or won’t respond well to chemo.
  • You’ll be more likely to get infections (opportunistic and sepsis).
  • You’ll be prone to blood clots.

Ask your doctor about your prognosis and steps you can take to care for yourself. Survival with Cushing syndrome and SCLC usually is under a year. If your doctor catches Cushing syndrome in SCLC early and gets the cortisol and cancer under control, you may live longer.

If you’ve noticed sudden and unexplained signs of Cushing syndrome when you aren’t taking glucocorticoid medicines, see a doctor. If this happens when you were healthy before, it suggests you may have a tumor somewhere in your body that’s making extra cortisol. It is rarely caused by SCLC and is more likely to be linked to a tumor that can be treated. Catching it early gives you the best prognosis.