Air pollution may shorten survival of patients with lung cancer
05 August 2016
Air pollution may shorten the survival of patients with lung cancer, suggests a population-based study by a team from the University of Southern California published in the journal Thorax. The trends were most noticeable for early stage disease, particularly adenocarcinoma—the most common type of non-small cell lung cancer, which accounts for 80% of lung cancer cases—the findings show.
Air pollution has been linked to a higher incidence of lung cancer and death, but little is known about its potential impact on an individual’s chances of survival after diagnosis.
In a bid to clarify this, the researchers tracked the health outcomes up until the end of 2011 of more than 352,000 people newly diagnosed with lung cancer between 1988 and 2009, and whose details had been entered into the US California Cancer Registry.
Their average age at diagnosis was 69. More than half (53%) of the cancers were diagnosed at an advanced stage (distant spread); and the average survival time for localized (early stage) disease was 3.6 years, falling to 1.3 years for regional spread, and just 4 months for distant spread.
For patients with early stage disease, average survival time was shortest for those with small and large cell cancers (around 1.5 years) and longest for those with adenocarcinoma (around 5 years).
Participants’ average exposure to nitrogen dioxide (NO2 ), ozone (O3 ), particulate matter of less than 10 um, and less than 2.5 um, in diameter (PM10 and PM2.5 ) was calculated using data from US Environmental Protection Agency air quality monitoring stations, mapped to area of residence.
Almost half of the study participants (45.4%) lived more than 1,500 meters away from a major interstate motorway. Less than 10% lived within a 300 metre radius of one.
Their risk of death from any cause was then estimated, according to disease stage and tumor cell type.
After taking account of these, and other potentially influential factors, the calculations showed that higher exposures to each of the four pollutants were associated with a correspondingly heightened risk of death and shorter average and 5-year survivals.
The magnitude of heightened risk was greatest for patients with early stage disease, among whom average survival was 2.4 years for those with high PM2.5 exposure (at least 16 ug/m3) and 5.7 years for those with low exposure (less than 10 ug/m3), for example.
Overall, for patients with early stage disease, risk of death from any cause was 30% greater for NO2 ; 26% greater for PM10; and 38% greater for PM2.5.5. The impact of exposure to O3 was small (4%).
These trends were particularly evident among patients with early stage adenocarcinoma.
As might be expected, survival for patients with advanced disease was poor, irrespective of exposure to pollutants.
This was an observational study—no firm conclusions can be drawn about cause and effect. And the researchers point to several caveats, including a lack of data on potentially important risk factors, such as an individual’s lifestyle, smoking status, and alcohol intake; and the inability to capture road traffic pollution.
Nevertheless, there are plausible biological mechanisms for the associations found, they say, as ambient air pollution has been classified as a cancer causing agent by the International Agency for Research on Cancer (IARC).
Our observed associations were clinically significant ([less than or equal to 38%] increased risk of death depending on stage and pollutant), suggesting that reductions in exposure have the potential to improve lung cancer survival.
—Eckel et al.
In a linked editorial, Dr Jaime Hart, of the Channing Division of Network Medicine, Brigham and Women’s Hospital and Harvard Medical School, points out that survival rates for lung cancer are poor, having improved only slightly in recent decades despite advances in treatment.
The most recent figures from the World Health Organization estimate that 1.8 million new cases of cancer were diagnosed in 2012 alone.
This study, along with two other previously published analyses on the impact of air pollution on cancer survival, provide compelling initial evidence that air pollution may be a potential target for future prevention and intervention studies to increase cancer survival.
—Jaime Hart
The findings underline the importance of the imposition of regulations on air pollution levels, Hart suggests.
Resources
Sandrah P Eckel, Myles Cockburn, Yu-Hsiang Shu, Huiyu Deng, Frederick W Lurmann, Lihua Liu, Frank D Gilliland (2016) “Air pollution affects lung cancer survival” Thorax doi: 10.1136/thoraxjnl-2015-207927
Jaime E Hart (2016) “Editorial: Air pollution affects lung cancer survival” Thorax doi: 10.1136/thoraxjnl-2016-208967
also smoking
Posted by: mahonj | 05 August 2016 at 06:55 AM
Well known facts. About the same findings were noted in France many years ago. Many schools were moved further away from highways to reduce risks to children.
We are smart enough to knowingly kill many of us with manmade pollution and then try to cure those cancers at very high cost. That keeps the pharma, doctors, hospitals and associates very happy.
The industries should have to pay for what they created via a health fund ($1,000 per ICEV should help)
Posted by: HarveyD | 05 August 2016 at 07:24 AM
What, and diminish GDP? Cleaning the air would be bad for jobs. Just listen to every "conservative" politician.
Posted by: JMartin | 05 August 2016 at 09:02 AM
@JM: That's a real growing problem. Too many of us earn their living by polluting the air/atmosphere, earth and water we use. Many get rich doing it on a very large scale. Others are employed to try to fix damages. It is a vicious circle.
Healthier people would perform better, live longer, need less health care, less prescribed drugs etc but how would you keep everybody busy and working without a good 5 to 20 years (China like) plans?
Building 200,000+ Km of very high speed electric rails, fixing all roads and bridges, upgrade all houses and building to reduce energy consumption, replace CPPs with clean REs, replace the 240,000,000 ICEVs with electrified vehicles, install 200,000+ quick charge charging e-facilities, install 20,000+ H2 stations, repair and/or replace many public schools, upgrade city streets, sewage and water lines. Find better ways to dispose of garbage, etc.,etc.,
Posted by: HarveyD | 05 August 2016 at 10:48 AM
I looks like you will live longer moving out of the big city. Hard to find work, but worth your life. Let someone else live in the city and enjoy their shorter life!
Posted by: Big Al | 05 August 2016 at 02:46 PM
Recent research into human evolution have shown some very interesting insights.
1: Homo sapiens sapiens are unique amongst apes in their ability to clear smoke pollution from the lungs.
No other surviving ape relatives have such resilience.
2: All Homo sapiens (out of Africa )) have Neanderthal genes the exception applies only to unmixed African races.
3:At the same time as Homo spp were learning to control fire for cooking and much later farming, Neanderthals became extinct.
4: This coincides with the appearance of tuberculosis in the fossil records.
It is suggested that the compromised lungs were the ideal breeding grounds for the tuberculosis bacilli.
Thought might as well throw that in.
Posted by: Arnold | 06 August 2016 at 02:39 PM
@HarveyD: Of course you are right, and that is what will happen eventually, even without a 5 or 20 year plan. But there are a lot of people and institutions that will resist those changes. Just as they resist renewable energy in spite of the fact that it has many advantages, including cost.
Posted by: JMartin | 06 August 2016 at 03:29 PM
http://www.abc.net.au/news/2016-07-26/did-early-campfires-trigger-the-emergence-of-tuberculosis/7658818
Posted by: Arnold | 06 August 2016 at 04:04 PM