• 6/20/2006
  • St. Petersburg, FL
  • V. Upender Rao
  • St. Petersburg Times (www.sptimes.com)

Researchers at the University of Texas M.D. Anderson Cancer Center found a high risk of developing a variety of cancers among parents, siblings and children of lung cancer patients who never smoked cigarettes.

Researchers at the University of Texas M.D. Anderson Cancer Center found a high risk of developing a variety of cancers (melanoma, head and neck, colorectal, prostate, lung and breast) among first-degree relatives (parents, siblings and children) of lung cancer patients who never smoked cigarettes.

Olga Gorlova, PhD, an assistant professor in the department of epidemiology, studied 2,465 first-degree relatives of 316 lung cancer patients who were nonsmokers. She compared the results with 2,442 first-degree relatives of 318 controls who were nonsmokers and who did not have cancer.

She found the following patterns and magnitude of increased risk among first-degree relatives of nonsmoking lung cancer patients:

– Overall risk of cancer was increased by 25 percent.

– First-degree relatives developed cancer 10 years earlier than the index case.

– Risk of developing a cancer at a younger age among relatives was estimated at 44 percent.

– Greater than a sixfold risk especially for lung cancer at a young age.

– A 68 percent risk of developing lung cancer at any age.

A study of patients with lung cancer, published in the Journal of the American Medical Association, showed an increased risk of lung cancer not only for the first-degree but also for the second- and third-degree relatives of nonsmoking lung cancer patients.

The excess risk was thought to be caused by shared environmental factors, but to a greater extent it was due to inherited genetic susceptibility.

A study from Singapore that appeared in the May 20 issue of the Journal of Clinical Oncology examined the role of non-tobacco-related factors in the development of lung cancer.

Thirty-two percent of all lung cancers diagnosed in Singapore were in patients who had never smoked.

Almost 70 percent of these patients were women. Seventy percent had adenocarcinoma as compared to squamous cell carcinoma, which was more prevalent among smokers.

Paradoxically, nonsmokers presented with a more advanced stage but had better survival than smokers.

The authors of this study hypothesized a causal role for cooking fumes, hormones, menstrual cycles and viral infections. Additional and more scientific evidence suggests differences in tumor biology between never-smokers and smokers.

T.J. Lynch, et al, reporting in the New England Journal of Medicine, showed a mutation in the EGFR (Epidermal Growth Factor Receptor) gene among these nonsmoking women with lung cancer. They also showed a dramatic and quick response of these cancers to geftinib, an inhibitor of the tyrosine kinase domain of the EGFR.

Although cigarette smoking is still the major cause of lung and other cancers, non-tobacco-related factors are also surfacing. Lung cancer in never-smokers is emerging as a distinct entity in the West, as well. As greater insight into the biology of these cancers evolves, it will be possible to formulate strategies for counseling, prevention and nontoxic treatments.

V. Upender Rao, MD, FACP, practices at the Cancer and Blood Disease Center in Lecanto.