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Lifetime Second-hand Smoke Exposure Impacts NSCLC Survival: Presented at AACR

By Charlene Laino

WASHINGTON, D.C. -- April 6, 2006 -- Early-stage non-small cell lung cancer (NSCLC) patients who are exposed to high levels of second-hand smoke over their lifetimes do not live as long, on average, as those with low levels of exposure, a new study suggests.

"We know that second-hand smoking increases the risk of lung cancer, and studies have suggested that it is associated with lung cancer mortality," said lead author Wei Zhou, MD, PhD, Research Scientist, Harvard School of Public Health, Boston, Massachusetts, United States.

"But this is the first study to show that second-hand smoking also is associated with lung cancer survival," Dr. Zhou reported here on April 4^th at the 97^th Annual Meeting of the American Association for Cancer Research (AACR).

The researchers examined the association between passive smoke exposure and overall survival in 393 patients with early-stage NSCLC who underwent surgical resection. Additionally, 32 (8%) patients received post-operative radiation and 5 (1%) patients received adjuvant chemotherapy.

The mean age of patients was 69 years and 49% of them were women. Eight percent had never smoked, 57% were former smokers, and 35% still smoked.

Nearly half suffered from adenocarcinoma, 28% had squamous cell carcinoma, 5% had large cell carcinoma, and 13% had bronchioloalveolar carcinoma. Fifty-three percent were Stage IA, 29% were Stage IB, and 18%, Stage IIA/IIB.

The researchers collected information on exposure to passive smoke at work, home, and leisure-time locations, such as restaurants. The questionnaire, administered by an interviewer, asked about length of exposure at each location over the patient's lifetime, before the diagnosis of lung cancer.

At a median follow-up of 66 months, 135 patients had relapsed and 213 had died.

Results showed that the overall 5-year survival rate decreased with increasing exposure: 71% of patients in the lowest quartile of exposure -- corresponding to less than 28 years on average -- were alive at 5 years, compared with 61% in the next highest quartile, and 49% in the third highest. In the highest quartile -- corresponding to more than 48 years of exposure -- 47% survived 5 years (P <.001, logrank test).

After adjustment for age, gender, stage of cancer, and the patients' own cigarette smoking over their lifetimes, those in the highest quartile for second-hand smoke exposure were 57% more likely to die than those in the lowest quartile (P trend =. 04).
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Workplace exposure appeared to be the most important factor. A statistically significant association was found for such exposures (adjusted hazards ratio [AHR], 1.71, 95% confidence interval [CI], 1.12-2.61), but not for exposure at home (AHR, 1.26, 95% CI, 0.86-1.86) or at leisure-time locations (AHR, 1.28; 95% CI, 0.83-1.95).

"The reason for the strong association with workplace exposure may be due both to the length of time people spend at work and the higher levels of smoke they could be exposed to there," Dr. Zhou said.

The researchers now plan to look at survival differences among lung cancer patients who are exposed to second-hand smoke after their diagnosis and at the genetic factors associated with second-hand smoking, smoking, and survival, he said.


[Presentation title: Second Hand Smoke Exposure and Survival in Early Stage Non-Small Cell Lung Cancer Patients. Abstract LB-345]

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