Many members have asked questions about increased risk of lung cancer among family members of people who have developed lung cancer. Overall, I have not highlighted this, partly because we don’t tend to highlight genetics as a major contributor of lung cancer risk. But the fact is that 10-15% of people who develop lung cancer never smoked, and the vast majority of smokers never develop lung cancer. And we see that the never-smoker population with lung cancer is disproportionately female (as covered in a prior post), and that multiple surgical series of show much higher proportions of never-smokers with lung cancer in studies from China (57% never-smokers in article here), and Japan (48% never-smokers in article here). Genetics must be an important modifier, since some people chain smoke for decades without developing lung cancer, while others can develop lung cancer with no obvious risk factors.
First, there have been family clusters of lung cancer described in reports for several decades (abstract here). Since then, many reports have come out that suggest an increased risk of developing lung cancer for people with first-degree relatives with lung cancer (article here; abstract here). This appears to be independent of smoking exposure, which often overlaps with familial genetic traits. However, the familial genetic risk appears to be greatest among family members of never-smokers and those with adenocarcinomas (article here; another article here). There are many studies out there with a wide range of methods to assess risk, in a wide range of populations. Taken together, many of the studies in smokers show an increased risk in the 30-50% range, and the risk for relatives of never-smokers with lung cancer may be in the range of 6x normal. But it’s important to consider that the risk of developing lung cancer for an individual person is still low, so it doesn’t mean that a family member of someone with lung cancer is likely to get it as well.
What can we do with this information? Of course, if we could learn more about preventive approaches that may be effective, whether supplements or other interventions, we could target higher risk ppopulations for treatments to reduce risk. Unfortunately, we haven’t identified any such approaches yet. There are a few screening studies that are enrolling people who may or may not have smoked but have a family history of lung cancer, so this designates them as higher risk even without the smoking history we’re usually focusing on to estimate increased risk for smoking. But smoking status is still a very dominant factor, so my assessment would be that the most important point to take away from the increased risk of lung cancer among immediate family members of people with lung cancer is to reduce the risk by not smoking. If risk is going to be elevated, better to have that increase be for a very, very slight baseline risk. We can’t control genetics, so most of what we can do is reduce the risks associated with behaviors that can be modified.
posted by Dr. West @ 9:25 pm link to this post
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July 23rd, 2007 at 8:38 pm
slcougar,
Practically speaking, it’s unfathomably complex and extraordinarily expensive. There are more than 170,000 new cases of lung cancer in the US alone, and doing detailed studies of everything they’ve ever been exposed to, plus integrating genetic research, which would obviously be involved, would cost more than we could even consider spending when federal research funds are being severely limited. Most of the research in cancer in the US at this time is sponsored by pharmaceutical companies, and the questions you’re asking don’t lead to answers that could justify their investment. I don’t mean to say it’s not worth knowing, but this is incredibly expensive, and even if we had all of the data, there are so many variables (food, chemicals, smoking history, location, genetics, lots more) that we still may not end up with most of the answers.
David,
I’m sorry for what you’re facing, as well as your whole family.
There are clearly many things we still need to learn about risk factors for lung cancer, especially genetics/family history. Tomorrow I’m seeing a new 41 year old female never-smoking Taiwanese woman who was urged to get screened by her father, after her mother developed metastatic NSCLC as a never-smoker. She had a stage IA NSCLC, resected, and is now seeing me to consider if there’s anything to be done to try to reduce risk in the future (my answer is nothing that we know of, I’m afraid). We see many cases that illustrate how central genetics are in risk for developing lung cancer.
-Dr. West
July 23rd, 2007 at 12:23 pm
Interesting thread. A quick rundown of my own family history :My Great grand mother (father’s side) died of stomach cancer. Father is a colon cancer survivor. One nephew that is a skin cancer survivor.One brother that died of nsclc after being staged at 3a. I’m currently in remission from stage 3b nsclc. So far I have undergone the same treatment as my brother. carbo/taxol concurrently with radiation. My father,I are both former smokers as was also a smoker.I have also worked in the pest control industry (3 years) and over 10 years in plastics manufacturing.
As for screening, I had 2 chest x rays in Nov. 06 both were interpreted as bronchitis. Three weeks after the second x ray,I had ct scan and was ultimately staged at 3b T4N3, squamous cell nsclc.I have another brother (never smoker) and a sister (former smoker) who both insisted on and were screened by CT. Both were negative.
Based on my own family history it would appear that genetics does play an important role. But there is also evidence to suggest other environmental factors may have been in play in my case at least.
While the jury may still be out concerning x ray versus ct scan, from my own experience it would seem that at least those folks who may be considered high risk be screened using ct scan.
Interesting thread!
David Barger