nos-trum. pronunciation: \nos'-trum\. noun. Etymology: Latin, neuter of noster our, ours.
1. a medicine of secret composition recommended by its preparer but usually without scientific proof of its effectiveness.
2. a usually questionable remedy or scheme.
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Monday, December 3, 2007


Note: don’t view this in text format. All the columns will be messed up.

Study suggests evening, night-shift workers may have increased risk of cancer.

The CBS Evening News (11/29, story 9, 0:50, Couric) reported that a study "from the World Health Organization (WHO) says working overnights can increase the risk of cancer." The finding is "based on research showing higher rates of breast and prostate cancer among shift workers."

NBC Nightly News (11/29, story 2, 2:05, Williams) added, "Some nine million American workers, one in ten, work the evening or night shifts in places like hospital wards, factories, and behind the counter in late-night restaurants." Anchor Brian Williams pointed out that working at night is "a way of life, and the only way to make a living, for millions of people in this country."

According to the AP (11/30, Cheng), the night shift joins "UV rays and diesel exhaust fumes" as items that are a "'probable' cause of cancer" on the WHO's list of carcinogens. The American Cancer Society is also expected to add night work to its list of cancer risks. Although there is no certainty about what specifically triggers the increased cancer risk, "scientists suspect that overnight work is dangerous because it disrupts" the body's circadian rhythm.

Doc D: Just getting out of bed every morning disrupts my circadian rhythm. Anyway, we now have a lifestyle that is a carcinogen. Are we going to Scare Ourselves To Death (SOTD)?

Can we talk?, as Joan Rivers says. We frequently hear stories about the “rising deaths due to (Blank), which should become a national priority, etc.” Here are the data on cancer over the last several decades:

Data Change

  1. The number of cancer cases, and deaths, is rising. In 1950, about 200K people died of cancer. In 1998, it was over 500K. That’s more than double. +150%
  2. But, there are more people. So a better estimate is “what’s the rate of death…how many per 100,000.” Do the math, and there were 140 per 100K in

1950, and 200 per 100K in 1998. So, the increase is smaller…but still scary. +43%

3. BUT, the population is different now. Fewer people die of the stuff that killed us a long time ago (TB, flu, pneumonia). People live longer and die of

of other things. So the average age of the population is going up (note: not life expectancy, but average age: just add up everybody’s age and divide

by the number of people). In 1998 it was 36. and cancer is primarily a disease of older people. More older people, more cancer. However, to compare

1950 and 1998 you have to correct for age. When you do that, you get the “age-adjusted rate” for cancer, and most of the increase disappears. +1%

4. Additionally, we know that a big chunk of cancer deaths comes from smoking (91% of lung cancer). This is a behavior, not some invisible

ray or chemical that’s going to extinguish all life on the planet. Let’s remove those folks from the total and see what happens: Doing so, the death rate

in 1950 was ~110/100K, and the rate in 1998 was ~75/100K. Wait! The trend has flipped, and the threat has become smaller, by almost a third. -30%

Put it all together, and the data shows that non-smokers have experienced falling risk of death from cancer. So, where’s the fire? Analyses like this show similar results for many of the diseases advocacy groups and the media want to you to support, and SOTD. All the data above is from official statistics, available to all. But the media hardly ever goes beyond item #1 above—because it sells more newspapers.

Two caveats. (1) There ARE diseases that are becoming more of a threat; more on that later. There are too many potentially confounding factors about night shift work to conclude the above, and I’m currently dubious. And finally, (2) the Grim Reaper wants me to include another statistic: the overall lifetime human death rate is 100%, and we’re not going to do much about that.

Doc D

Opinions my own


Anonymous said...

Do Evening and Night Shift workers smoke more often too?

Doc D said...

This doesn't qualify as good research, but, to answer your question, the research hasn't been done on smoking and night shift (to my knowledge). If you are trying to point to other variables that may be involved in this alleged cancer risk, good job. Almost all of these research "associations" turn out to be due to other causes.

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