i’m pretty ignorant on this so i’m hoping the science folks in here will flesh out my thoughts.
if cancer rates are skyrocketing in recent decades, can’t we link it strongly to environmental pollution?
was cancer rare before modern times and modern carcinogens?
why do we make such an effort to “cure” cancer when we generally cause it? are we in a massive state of denial?
when they say people are genetically prone to get cancer, are they destined to get cancer or are they just more likely to develop it when exposed to cancer-causing agents? would they still get cancer if they lived on a pristinely clean desert island not beneath the ozone hole?
please, please, please elaborate if you know more than me on the subject–shouldn’t be hard, right? thanks for reading this tripe…
I’m not too well-informed on this, but what I’ve heard lately is that cancer is primarily a disease of old age (you replicate cells often enough, they’re bound to mutate or something like that). So the increase in cancer rates may in fact be simply because more people are living longer.
Still if this goes to GD, there’s probably something to the idea that we’ve contributed to the problem by environmental pollution. There’s a few more consequences to our pollution than just cancer rates, so even if it’s not related, that’s no reason to forget about pollution.
panama jack
Man thinks 'cause he rules the earth
he can do with it as he pleases
And if things don’t change soon, he will.
- Bob Dylan, “License To Kill”
Furthermore, when someone dies of cancer it is now identified as cancer–I have always had the impression that today’s cancer was yeasterday’s “wasting disease”
IIRC cancer is not a mutated cell but a cell with your correct genetic code, but with certain traits turned on all the time.
It is assumed that it takes at least 2 difrent substances to cause cancer, an initiator and a accelerator. If you are never expesed to the initiator - you won’t get it ( although there are many initiators). Even if you are exposed to the initiator, but not exposed to the accelerator - nothing should happen. Also I think they are looking for a 3rd component but nothing confirmed. I think there are some substances that can serve as both an initator and accelerator.
Another note - unlike toxic substances which have a ‘safe’ dose level- carcinogens have no such limit except, well at least in theory, at the molecular level (you need al least 1 molecule).
As for are we creating cancer through technology. I think we are creating more initiators and accelerators AND people are living longer so people are more likely to be exposed. And once they get cancer, probally live long enough for it to be diagnosed.
No, we can’t. One reason, as has already been pointed out, is that we are living longer. Cancer is more likely to occur the longer you live. If you die at, say, 30, you are a lot less likely to get cancer than if you live to 80.
Um. Huh?
They are more likely to develop it – period. Cancer-causing agents may or may not have anything to do with it.
There is no way to know.
A book you might want to read is Cancer: The Evolutionary Legacy, by Dr. Mel Greaves. He deals with a lot of these issues.
I wrote an article about this book, including an interview with the author. The article is reprinted at themestream.com, but I cannot post the link here because I get paid a small amount per person who reads it (although it is free for the reader). If you are interested, you can either go there and do a search or e-mail me for the link.
quote:
would they still get cancer if they lived on a pristinely clean desert island not beneath the ozone hole?
DaveB: here is no way to know.
I would add that cancer is a grab-bag term to describe uncontrolled cell proliferation and this can occur without external causes.
Humans (and most other species) have genes that are called proto-oncogenes which can be mutated to become oncogenes–genes that can induce cell transformation into cancer cells. In fact, most retroviral oncogenes are acquired from genes present in the normal host genome (the first and classic example being the src gene of Rous Sarcoma Virus); and, if they are part of the genome, they don’t need to be introduced by a cancer causing virus (Stehlin et al, 1976; Nature; 260; pp 170-73).
Simplistically, oncogenes produce proteins that induce DNA replication and cell growth/division–and inappropriate cell growth/division ‘is’ cancer. A lot of these proteins are downstream second messengers or kinases of the normal extracellular growth factors that tell the cell to divide. Being present without the normal extracellular factor is bad news.
These proto-oncogenes can be induced to become oncogenes–“cancer producing genes”–in the absence of external factors via mechanisms for defective DNA repair or replication (point mutations), or chromosomal recombination that activates these genes. And, these processes are always occuring in the normal cell.
As DaveB says, there’s is no way to tell (although I bet some researchers somewhere have gotten money to study this), but it’s a good bet it occurs.
Cancer is obviously a complex disease involving still to be understood molecular pathways, which makes a single cure impossible at present.
I remember hearing about a study which examined historical and current cancer rates on an age adjusted basis.
The conclusion that it reached was that for a person of a given age, the chance that that person would develop cancer was largely the same over the historical period of the study. The thing that changed was that the proportion of the population living to greater ages has increased significantly, causing the overall cancer rate to rise.
Now I remember discussing this survey about a year ago, but I don’t recall any of the details.
“Cancer” is not a single disease, nor does it have a single cause. Off the top of my head, I can think of at least eight contributing and/or predisposing factors. IMHO, most are not “man-made”.
Age - as we age so do our cells, i.e. every time a cell divides its DNA gets a bit altered (lengthened). The more alterations that occur, the greater the chance of a mutation arising that can contribute to the cell becoming cancerous. Bottom line is that aging itself can lead to cancer.
Genetic Tendency - there are numerous examples of cancers arising on a familial or inherited basis. Examples include inherited genetic defects in DNA repair, tumour suppression, and immune response (see below).
Infections - again, there are many prototypes including Ebstein-Barr virus (mono), Herpes Simplex and Hepatitis B viruses. Less obvious than viral causes are parasitic causes. A prime example here is of schistosomiasis which is a major contributor to bladder cancer in North East Africa.
Immunologic Problems - people receiving drugs that modify their immune system develop cancer, as do people with inherited defects in immune function.
Increased Cell Turnover - so, for example, people with inflammation in the bowel, where there is constant turnover of the bowel lining cells are at risk of bowel cancer. Similarly, poorly fitting dentures that lead to repeated injury, and regeneration, of mouth cells promote the development of oral cancers.
Scarring - the repair process to injury can eventually lead to cancer developing at the site of injury, eg. people whose esophagus have been burned by lye (post suicide attempt), eg. cancers arising at site of scars in the lung.
Radiation - much of this is naturally occurring, eg. solar, uranium fission in earth’s crust
Chemical - even chemical carcinogens can arise naturally and are not just man-made, eg. certain molds on nuts, eg. traditional fermented drinks in Iran and Afghanistan
So, while it is clearly true that some cancers arise because of man’s pollution etc., it is equally the case that many have nothing whatsoever to do with our undertakings.
I recall reading that lung cancer has shot up this century because cigarettes were given out free to GIs in WW1 thus hooking alot of people on the evil weed.
This article comes from the ultra-conservative Cato institute. How anyone can take them seriously is beyond me. This is not a thoughtful piece on bad science like you’d expect from a site called “junkscience”, but rather raw right-wing propaganda. I’ve read the site before - it’s like that all the time.
Understanding the mechanisms of cancer helps. Some good sources have been cited. I just happen to be reading a book called ‘Borderlands of Science’ that sweeps across a broad area of science – explaining fertile areas for science fiction writers.
Charles Sheffield (pp. 140-145) treats the biochemistry of cell replication and explains how cancer cells work. Aging and cancer are related by presence of an enzyme called telomerase: too little and cells don’t reproduce, so the organs age; too much and cancer runs wild. Some of the previous posts treat it well and provide good reference links too.
Regarding the “desert island” question, does anybody have statistics for causes of death on Tristan del Cunha? It’s a little island in the South Atlantic which is believed to be the most remote continuously-inhabited spot on the planet, and average lifespan there is something like 85 years.
By the way, puddleglum, great username. I just re-read The Silver Chair a couple of weeks ago.
Well, lung cancer is primarily man made, but not by pollution. Most lung cancer is caused by cigarette smoking.
Pollution levels are dropping, not rising, so if cancer were primarily caused by pollution, cancer would be dropping as well. Since the population of old people is growing, so does the incidence of cancer.
Another factor is increased public awareness of certain forms of cancer. Prostate cancer, for example, is being diagnosed more nowadays, but some doctors consider it a normal part of aging. Chances are good that most 80 year old men will get or have already gotten prostate cancer. If it is the slow-growing kind (as most of it is), it will have little or no effect on life span. Most 80 year old men die of something else before they are effected by prostate cancer. It is a common finding at autopsy of elderly men.
Chronos, I’ve had a fun time running down your query, but I haven’t found much.
The people of Tristan da Cunha were recently studied by a biotech firm looking for–and purportedly identifying–an “asthma gene.” It seems that something like 30-50% of the population develops asthma.
However, according to this site, the people of the island were initially unwilling to participate in the study. They finally submitted, and the Sequana Theraputics Corporation made a boatload of money off of the research. The people of Tristan recieved practically no compensation. That, I think, bodes ill for any cancer research that might be done on them, but you never know. The people of Tristan didn’t even have money until 1942.