by Dr. C.H. Weaver M.D. 11/2018
Quit Smoking - Its Never Too Late
The results of a study published in the British Journal of Cancer indicate that men who quit smoking can significantly reduce their risk of developing lung cancer. The benefit of quitting was found even if the men waited until middle age to do so.(1)
Lung cancer is the most common of all cancers world wide, and smoking can be attributed to 85% of diagnosed cases of lung cancer due to the damage of lungs caused by cigarettes. Factors determining a smoker’s risk include the number of years the person has been smoking, as well as the number of cigarettes smoked each day.
In this study, researchers gathered data from 6,523 patients who had been diagnosed with lung cancer and 9,648 individuals who had not been diagnosed with lung cancer from the United Kingdom, Germany, Italy and Sweden. The risk of developing lung cancer among smokers were between 6%-15% in the UK, Germany, Italy and Sweden. The risk of developing lung cancer was reduced by 80%-91% in men who quit smoking before the age of 40. In further analysis, the risk of developing lung cancer was reduced by 57%-69% in men who quit smoking before the age of 50.(1)
The Environmental Protection Agency Issues Health Advisory on Radon to Prevent Lung Cancer
The US Environmental Protection Agency (EPA) has urged Americans to test for radon gas in their homes to prevent lung cancer.(2) In a separate report, researchers from Europe published the latest analysis of the effects of radon in homes and the risk of lung cancer in the February issue of the British Journal of Medicine .(3,4)
Radon gas is a term used for the short-lived radioactive disintegration products of the chemically inert gas radon-222. Radon occurs naturally from the decay of uranium-238. Radon affects humans by seeping through the soil and into buildings. Some buildings have a high concentration of radon and others a low concentration and the only way to know is by direct testing. The EPA report suggests that radon can accumulate in homes, especially in the winter months, which is the optimal time they suggest for testing. The EPA report suggests that this is a problem for 1 in 15 homes in the US.
The reason to test for radon is that exposure over long periods of time causes lung cancer. The EPA report stated that this translates to 20,000 lung cancer deaths per year in the US. The article in the British Journal of Medicine looked at over 7,000 cases of lung cancer and compared radon exposure to over 14,000 control subjects without lung cancer. This data set came from 13 European countries. They found that the average concentration of radon in homes of lung cancer victims was higher than in control patients. They found an increase in the incidence of lung cancer with an increase in radon concentrations in the home. When they divided the risk of lung cancer by radon concentrations of 0, 100, and 400 Bq/m3, they reported that non-smokers would have a lung cancer incidence of 0.4%, 0.5%, and 0.7%, respectively. For smokers, the increase in lung cancer was 10%, 12% and 16%, respectively, at the three different levels of exposure. These researchers suggest that 2% of all lung cancer deaths from cancer in Europe are caused by radon exposure. In the accompanying commentary, the authors noted that it was difficult to get people to respond to an unseen menace.
The Surgeon General pointed out that “inexpensive do-it-yourself radon test kits are available at local hardware stores. EPA recommends that houses with radon levels of four picocuries or higher of radon should and can be fixed to prevent accumulation of radon gas indoors.” To decrease radon levels, the primary action is to ventilate basements and/areas under living quarters. It would appear that individuals at the highest risk are those who live in single family dwellings. It would appear that radon exposure in upper floors of apartment buildings would be minimal. The BMJ article is of interest as it points out the significant added risk of radon to tobacco exposure.
Cruciferous Vegetables May Reduce Risk of Lung Cancer
According to a study published in Lancet, cruciferous vegetables such as cabbage, broccoli, and brussels sprouts may reduce the risk of lung cancer; the extent of protection appears to vary by genotype.
Studies of diet and lung cancer have consistently reported that eating vegetables-particularly cruciferous vegetables such as cabbage and broccoli-may protect against cancer.
In order to provide additional information about the link between vegetable intake and lung cancer, an international group of researchers assessed whether the anti-lung cancer benefit of eating vegetables varied by a person’s genotype.
Research focused on two genes: GSTM1 and GSTT1. Patients with “null” variants of one or both of these genes have lower levels of glutathione-S-transferase, an enzyme involved in the elimination of isothiocyanates from the body. Because isothiocyanates are thought to be one of the components of vegetables that protect against cancer, people who have less ability to eliminate this compound (as a result of having a null variant of the GSTM1 and/or GSTT1 gene) may derive more of an anticancer effect from vegetables.
The study involved 2141 subjects with lung cancer and a comparison group of 2168 subjects without lung cancer. All patients were enrolled from countries in central and eastern Europe. Information about cruciferous vegetable intake was collected from a questionnaire that asked about cabbage and a combination of brussels sprouts and broccoli.(5)
Overall, people who ate higher levels of cruciferous vegetables were less likely to develop lung cancer. People who ate cruciferous vegetables at least one a week had a 22% lower risk of lung cancer compared to people who ate cruciferous vegetables less than monthly. As expected, the benefit was particularly apparent among people with the null variant of GSTM1, GSTT1, or both. Among those with the highest vegetable intake, risk of lung cancer was reduced by 33% among people who were GSTM1 null, by 37% among people who were GSTT1 null, and by 72% among those who were both GSTM1 null and GSTT1 null. Among subjects who were not null for either gene, there was no significant link between vegetable intake and lung cancer risk.
The researchers conclude, “These data provide strong evidence for a substantial protective effect of cruciferous vegetable consumption on lung cancer.”
- Crispo A, Brennan P, Jockel KH, et al. The cumulative risk of lung cancer among current, ex- and never smokers in European men. British Journal of Cancer. Advanced online publication August 3, 2004; doi: 10.1038/sjc.bjc6602078.
- Hill ADD, Auvinen A, Barros-Dios JM, et al. Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies. British Journal of Medicine . 2005;330:220-225.
- Watts G. Science Commentary: Radon blues. British Journal of Medicine. 2005;330:226-227
- Brennan P, Hsu CC, Moullan N et al. Effect of Cruciferous Vegetables on Lung Cancer in Patients Stratified by Genetic Status: a Mendelian Randomisation Approach. Lancet. 2005;366:1558-60.