Smoking Seems to Make Aromatase Inhibitors Less Effective

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Smoking has been linked to a number of diseases and is associated with a higher risk of breast cancer in younger, premenopausal women. Research also has shown that there may be a link between very heavy secondhand smoke exposure and breast cancer risk in postmenopausal women.

Smoking also may increase complications from breast cancer treatment, including:

  • damage to the lungs from radiation therapy
  • difficulty healing after surgery and breast reconstruction
  • higher risk of blood clots when taking hormonal therapy medicine

Researchers have wondered if smoking before breast cancer surgery affected the outcomes of specific treatments after the surgery.

A study suggests that smoking makes a class of hormonal therapy medicines, the aromatase inhibitors, much less effective.

The research was published online on June 9, 2016 by the British Journal of Cancer. Read the abstract of “Impacts of smoking on endocrine treatment response in a prospective breast cancer cohort.”

After surgery, women diagnosed with hormone-receptor-positive breast cancer usually take hormonal therapy medicine to reduce the risk of the cancer coming back (recurrence). Hormonal therapy medicines work in two ways:

  • by lowering the amount of estrogen in the body
  • by blocking the action of estrogen on breast cancer cells

There are several types of hormonal therapy medicines. Tamoxifen, a selective estrogen receptor modulator (SERM), is one of the most well-known. Tamoxifen can be used to treat both premenopausal and postmenopausal women. In 2005, the aromatase inhibitors:

  • Arimidex (chemical name: anastrozole)
  • Aromasin (chemical name: exemestane)
  • Femara (chemical name: letrozole)

were shown to be more effective at reducing recurrence risk in postmenopausal women and are now used more often than tamoxifen to treat women who’ve gone through menopause.

Aromatase inhibitors aren’t commonly used to reduce recurrence risk in premenopausal women. Still, in some cases a premenopausal woman may take medicine to suppress the function of her ovaries and take an aromatase inhibitor.

To do the study, the researchers followed 1,016 women from southern Sweden who were diagnosed with breast cancer between 2002 and 2012 for about 5 years. When the women scheduled breast cancer surgery, they were asked if they smoked:

  • 21% said they were regular or social smokers (206 women)
  • 79% said they were non-smokers (810 women)

Overall, there didn’t seem to be a link between smoking and the risk of recurrence.

Still, when the researchers looked at just the 309 women older than age 50 diagnosed with estrogen-receptor-positive disease who were treated with an aromatase inhibitor after surgery, they found that smoking increased the risk of recurrence as well as the risk of dying from breast cancer.

"Smokers who were treated with aromatase inhibitors had a three times higher risk of recurrence of breast cancer compared with the non-smokers who got the same treatment," said Helena Jernström, associate professor at Lund University and lead author of the study. "The study also showed that the smokers also had an increased risk of dying, either from the breast cancer or from other illnesses, during the time we followed them.

"The treatment with aromatase inhibitors worked significantly better in the non-smoking patients," she continued. "However, we saw little or no difference between smokers and non-smokers among patients treated with the drug tamoxifen, radiotherapy, or chemotherapy. More studies are needed, but our findings are important as many breast cancer patients receive this type of treatment."

The researchers said they were surprised that so few women quit smoking during treatment, even though they were told how important it was to quit. Only 10% of the 206 smokers stopped smoking in the first year after breast cancer surgery. This number was so small that the researchers couldn’t study whether quitting smoking during treatment had any effect.

If you don't smoke, don't start. If you do smoke, use every resource you can find to help you quit. Knowing about all of the problems associated with smoking isn't always enough to make you quit. Smoking is a habit that's very hard to break. Fortunately, if you're serious about trying, you have lots of help:

  • The American Lung Association offers a free online smoking cessation program. The American Cancer Society also has a quit smoking program. You can also call the American Cancer Society at 1-800-ACS-2345 to get support and free advice on how to stop smoking from trained counselors.
  • Medicines to help you quit can be taken as a pill, chewed as gum, or worn as a patch on the skin. Ask your doctor if one of these might be right for you.
  • Acupuncture and meditation may help ease cigarette cravings.
  • It's also easier if you have a friend who's also quitting or who can cheer you on when you're feeling you can't make it on your own.
  • The Discussion Board has a thread titled Stop Smoking Support Thread, where you can meet others to give and receive support to quit smoking.

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