Study Links Smoking To Higher Risk Of Death From Breast Cancer And Other Causes

Smokers with breast cancer were more likely to die of breast cancer, heart disease and diseases of organs in the chest according to recent study
Breast Cancer News
August 18, 2016
By: 
Eric Fitzsimmons, Copy Editor and Content Coordinator
Reviewed By: 
Lillie D. Shockney, RN, BS, MAS

A new study published in the Journal of Clinicalinfo-icon Oncologyinfo-icon looked at how smoking may affect women diagnosed with breast cancer. The study found women diagnosed with breast cancer who said they were active or recent smokers had a greater risk of dying from breast cancer than women who have never smoked or have quit before diagnosisinfo-icon.

Background and Goals

Earlier studies, including a 2014 report from the Surgeoninfo-icon General, have suggested a link between smoking and breast cancer, but there has not been enough evidence to say that smoking causes breast cancer.

Smokers are more likely to die of lung cancer and other diseases related to organs in the chest and throat. Studies of women with breast cancer have found those who had been smokers before diagnosis were more likely to die of breast cancer than women who had never smoked. Researchers in this study wanted to learn more about that link and what happens when women continue to smoke after diagnosis.

Design

Researchers looked at data from the Collaborative Breast Cancer Study (CBCS) in which women between the ages of 20 and 79, with a history of early-stage breast cancerinfo-icon, participated through phone interviews. The women were asked about their health histories and about how much they smoked and drank alcohol before diagnosis. A total of 20,691 women participated in this study.

Researchers also used data from the Collaborative Women’s Longevity Study (CWLS), which sent surveys through the mail to women who had participated in the CBCS. The survey asked each woman about her health and behaviors since being diagnosed with breast cancer. Questionnaires were completed a medianinfo-icon of 6 years after diagnosis. The researchers used responses from 4,562 women after excluding some who had a recurrenceinfo-icon between the two studies or were in poor health at the time of the CWLS.

Results

Women who smoked, especially those who said they were regularly smoking around the time of their diagnosis or had smoked for a long period even if they quit before diagnosis, showed a higher risk of dying from breast cancer in the time covered by the study. Those who said they were still active smokers less than a year before they were diagnosed were 25 percent more likely to die of breast cancer than women who had never smoked, according to the study.

The risk of death from breast cancer was highest for:

  • People who had smoked for 30 or more years
  • Those with the greatest exposure to tobacco (which counts how many packs a day are smoked over the years smoked. For example, one pack smoked every day over 5 years would be considered 5 pack-years)
  • Former smokers who quit within the 5 years before diagnosis

These factors were related to higher risk individually but had a greater effect when more than one was true for one person. Someone who smoked for over 30 years had a greater risk if she was still smoking around the time of her diagnosis.

The overall chance of dying from breast cancer was still less than 20 percent for most groups in this study, even with the higher risk with smoking. The difference between groups was larger when all causes of death were included.

Smoking has long been linked to higher rates of lung cancer and other diseases related to breathing and heart diseases. Former and recent smokers in this study were more likely to die of these diseases than people who had never smoked.

In the survey about women’s habits after diagnosis, women who had been smoking but quit after their breast cancer diagnosis had a lower risk of death by breast cancer than those who continued to smoke. But the difference was not statistically significantinfo-icon and how quitting after diagnosis impacts breast cancer outcomes is still unclear.

Limitations

Researchers noted participants could have misreported how much they smoked. But the researchers found the number of women in the study who said they were actively smoking after treatment for breast cancer to be consistent with previous reports. There was only one survey for post-diagnosis smoking habits, so researchers could not know if participants quit after that point. Information about exposure to secondhand smoke was not included in the survey.

The survey did not ask about the hormone receptorinfo-icon status of breast tumors. Researchers noted other studies have looked into the effect of smoking on hormone receptor-positive breast cancer but those results have been mixed.

What This Means for You

A history of smoking was shown to raise the chance of dying from breast cancer, but this higher risk was slight overall. Even so, smoking comes with a number of health risks. Results here suggest quitting even after diagnosis may lessen the risk of dying of breast cancer, but that is one area that calls for more study.

If you are a long-term smoker, remember that you cannot change choices made in the past. It may seem hopeless to think that past behavior can impact your breast cancer experience. Try not to focus on the past; you can improve your overall health now by making healthier choices in your diet, lifestyle and habits. If you’re still in treatment, being in better general health can help you copeinfo-icon with breast cancer treatment and its side effects.

You can find more information and resources at smokefree.gov from the U.S. Department of Health and Human Services. The site provides support, tips, programs and even apps to help smokers quit. You may also find counselinginfo-icon through your treatment center or by talking with people who have had similar experiences, either in your community or through resources such as LBBC’s Breast Cancer Helpline, available toll-free at (888) 753-LBBC (5222).

Passarelli, M, Newcomb, P, Hampton, J, et al. Cigarette Smoking Before and After Breast Cancer Diagnosis: Mortality From Breast Cancer and Smoking-Related Diseases. Journal of Clinical Oncology. 2016;34(12):1315-1322. April 20, 2016; doi:10.1200/jco.2015.63.9328.

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