Workplace exposure to secondhand smoke increases women’s lung cancer risk

  Article date: 2002/11/13,Milk And Cheese May Help Protect Against Cancer

A group of German researchers found, not surprisingly, that contact with smoke at work or at home, or working in a place with exposure to known cancer-causing chemicals, may increase women’s chances of developing lung cancer.

The scientists also found that women with some lung diseases or those being treated with radiation may be at increased risk for lung cancer.
Some Dairy Products Beneficial

But they also found several things that might protect some women from developing cancer — eating fruits, fresh vegetables, drinking milk, and especially, eating cheese.

Women who drank at least a cup of milk daily had a reduced risk compared to women who drank milk less than monthly, wrote Michaela Kreuzer, PhD, of the Federal Office for Radiation Protection, Institute of Radiation Hygiene, Neuherberg, Germany.

But women who ate cheese every day had their risk reduced by a factor of three, compared to women who ate it weekly or less, Kreuzer and her colleagues found.

In Europe, lung cancer is the third most common cancer death among women and has been on the rise since the 1970s. According to the American Cancer Society (ACS), lung cancer is the leading cause of cancer death among both men and women in the US. While the number of annual cases in men is declining, in women in the US it has only reached a plateau.

Smoking is blamed on both continents. While other factors may contribute to the development of lung cancer, such as environmental (or second-hand) tobacco smoke, radon in homes, occupational hazards, prior cancer, diet, and hormones, the researchers wanted to see how much each of these contributed to women’s risk.

"Active smoking as the major risk factor for lung cancer has been studied extensively, while other risk factors that might contribute to lung cancer, although to a much lower extent, are not nearly as well quantified," Kreuzer said.

"Since some of the potential risk factors can be avoided or at least reduced — passive smoke, radon in homes, occupational exposure to carcinogens — it is important to investigate their impact," she said.

To do this, Kreuzer looked at women who had smoked less than 400 cigarettes in their lifetimes. They compared information on potential risk factors in a group of women lung cancer patients with that of women without lung cancer .

The first group was made up of 234 East and West German women age 35 to 75 with lung cancer (adenocarcinoma, squamous cell carcinoma, or small cell lung cancer). Their average age was 62. The women came from 15 clinics in the study area.

The second group was 535 East and West German non-smoking women, with an average age of 60. They were chosen at random from the general population.

Both groups were interviewed in person using the same set of questions.
Researchers Weigh Other Cancer-Causing Factors

Looking at the results for each factor, the researchers found that both groups had a about the same rates of prior non-malignant lung disease (tuberculosis, chronic bronchitis, asthma, and emphysema). But, women who had prior pneumonia had a 1.6-fold increased lung cancer risk.

About one-third of each group reported a history of cancer in first-degree relatives (mother, father, sister, or brother). But, a positive family history of lung cancer didn’t appear to increase risk, the authors wrote.

Women highly exposed to smoke from a spouse compared to women with no or low exposure had a 1.7-fold non-significantly increased risk, the authors wrote. But, women highly exposed to smoke at work had a 2.6-fold increased risk.

This difference in risk could be because there are more smokers in the workplace, and therefore more exposure to smoke at work than at home.

When the authors looked at the women’s diets, they found that eating a lot of fruits and fresh vegetables seemed to have a protective effect, as did drinking milk and eating cheese daily.

While eating fresh vegetables and fruits has been shown in other studies to reduce lung cancer risk, Kreuzer said, the protective effect of drinking milk and eating cheese "is a new finding in our study."

While the researchers said they did not know how eating cheese protected the women, they said it contained an ingredient that has been suggested to show anti-cancer effects in other studies.

"But it is also possible that women who ate cheese had an overall healthier diet," said Kreuzer. She cautioned, however, "This finding has to be confirmed in other studies."

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