Tuesday, October 11, 2011

Cancer Screening-Overused for Older Individuals

Cancer is one of the most frightening diseases out there. Many forms are difficult to treat, particularly if they are not caught early. The routine use of many screening tests to catch cancer in its early, more treatable phases over the last few decades has allowed many individuals to be cured before their disease progressed into its later stages. However, the overriding fear of cancer in public consciousness may have led to an unintended effect. Many older adults, long past the age when they should be receiving screening for some forms of cancer, are still receiving these tests on a regular basis. A recent report reveals that Medicare spent $1.9 billion between 2003 and 2008 on cancer screening for adults who were older than government recommended age guidelines for cancer screenings.


On the plus side, all this spending does create jobs that let people look at breasts all day.

Why do these age guidelines exist?
One of the reasons why cancer screenings eventually lose efficacy is that life is finite. Eventually heart disease, strokes, or other conditions are going to end it. If someone is ninety years old and has severe heart disease, they are going to be dead before a newly discovered case of prostate cancer becomes a problem. Cancer has become a rather potent fear in society so it's hard to just believe that letting it go on and grow is the best option, but sometimes it simply is. There's no reason to put a person with a host of other health problems through chemotherapy and surgery for a tumor that isn't going to cause any problems before the individual is likely to die.


Although it does give a good excuse for wearing a Hawaiian shirt.

Why are excessive screenings harmful?
There's a basic idea that more screenings and tests must be better than less. After all, if it can potentially locate something that can be treated early, why not do it? The problem with this thinking is that these tests and screenings are expensive and they are not always accurate.

Every screening test has the risk of false negatives and false positives. A false negative means that a case of cancer was missed by the test. A false positive means that a case of cancer was falsely identified as being present. A false negative means that cancer isn't being treated and may even result in early cancer symptoms being ignored because, hey, the screening last year didn't show any problems. A false positive is extremely frightening for a patient and may result in unnecessary biopsies and surgical procedures, which also pose their own risks.


Wait... it was benign?

An additional problem is that screening tests should also be shown to have some sort of benefit on survival of patients. For example, let's say there's a new screening test for metastatic pancreatic cancer. It detects it successfully 100% of the time. Unfortunately, there isn't anything at all that can really be done to treat metastatic pancreatic cancer, the median survival is between 6-10 months. At best, treatment will give a patient a couple months of extra life. This means that there is no point in using this screening test for the general population-it will not cause any improvements in survival and is thus just a waste of money.

It's actually pretty difficult to create screening tests that do not have too many false negatives or positives and are shown to improve survival rates for patients. Even some formerly routine tests are more controversial lately as research results have come back.

A good example is the Prostate-Specific Antigen test for prostate cancer in men. It used to be done routinely for men after age 50, but now the evidence reviewed by the United States Preventive Services Task Force suggests that Prostate-specific antigen–based screening results in small or no reduction in prostate cancer–specific mortality and is associated with harms related to subsequent evaluation and treatments, some of which may be unnecessary. Many physicians are still debating whether to continue performing the test or not, but it's certainly an example of a potentially gigantic waste of money.

Conclusion
Cancer screenings are a great tool to reduce cancer-associated mortality when they are used appropriately. However, they have become over-utilized in inappropriate groups of people, particularly the elderly. In many cases cancer may simply be able to be ignored in older adults because they are likely to die from something else first. As one example, many older men die WITH prostate cancer, but very few die FROM prostate cancer.

Perhaps the best way to view this information is to take a look at the overall health status of the person in question. If they are an extremely healthy eighty year old, maybe it's worth doing a screening because they may get a decade or more of life out of an early identification and treatment of cancer. If they have severe heart damage, Alzheimer's disease, and other problems, maybe it's a better idea to avoid doing the screening.

Thursday, October 6, 2011

Deus ex Machina Ruins Another Novel-Out of the Dark

A few months ago I read the book Out of the Dark by David Weber. It caught my eye in the library for two reasons. One was that the cover featured a passing interest of mine, an alien invasion of present-day Earth.


Although I wonder how that floating city stays in the air.

The other reason was that it was a stand-alone novel. I figured this meant I could get a satisfying ending without having to read four or five other books afterward. It's a rare thing to find a single fantasy or science fiction novel anymore. I suppose the trilogy or series is something of a standard of the genres now, but most authors just pad their books with trivial details and conflicts just so they can get three books out of one big idea. Unfortunately, my expectations for a good ending were betrayed by Mr. Weber. Let's go through the book and see what the problem was.

The Plot
The basic plot is that a group of aliens invade the Earth hoping to colonize it and use us as a client species for their own future conquests. They were dispatched because of a scouting expedition that witnessed the battle of Agincourt and were apparently horrified by the barbarity of man in that fight. Unfortunately for the aliens, humanity advanced at a much faster rate than any other species that they had previously encountered. They expected humans to stay at a Medieval level of technical development, so when they arrived to find assault rifles, Abrams tanks, and the internet they were taken aback. However, the aliens had the ability to bombard the Earth with meteorites so they went ahead with their invasion, destroying most major cities, military bases, and armies with their orbital bombardment.

At this point, the story got quite interesting. Although the aliens had impressive looking technology, such as hover tanks, spacecraft, and drones, their tactics and equipment were inferior to modern weaponry. Their ground based vehicles did not have enough armor to withstand handheld anti-tank weapons or even small arms fire in some instances. Additionally, their infantry were mostly unarmored with weapons inferior in range and power to modern firearms. They also used appalling tactics to fight against human forces.

The explanation given for this was that the aliens were accustomed to fighting technologically inferior foes so all of their equipment was developed with subduing primitive societies in mind. Armor that blocks a spear isn't very difficult to design while armor that stops a high explosive shell is quite a bit more challenging. The result of this imbalance in power was that the only superior force the aliens could offer was their ability to send in meteorites to destroy anyone resisting them. This is a rather indiscriminate way to eliminate enemies which limits its viability since the aliens wished to colonize, not destroy, Earth.

Mr. Weber did an excellent job through the beginning and middle of his book by describing the improvised efforts that local forces throughout the world used to battle the aliens. In the United States, national guard forces who grabbed equipment from their armories and civilians with personal firearms inflicted a heavy toll on the aliens. Similar events occurred in Russia and Romania. The aliens, in reaction to this, tried to build trust and rapport with humanity by working with some of the few remaining human authority figures to get the remaining rebels to stand down.

The building drama was that the aliens realized that they were going to lose way too many of their soldiers and vehicles trying to fight this war so they decided that they had to find a way to end it. Since they still wanted Earth, an asteroid bombardment was out of the question. That left them to decide that a virus was a good idea, which they decided to develop on the surface using human test subjects. Some information on this leaked out to the resistance forces, who realized that they needed to do something about this.

The Problem
At this point, I had about fifty pages left in the novel and wondered how the hell David Weber was going to end this book successfully. I figured maybe he would have a resistance group break into one of the virus manufacturing facilities and retool it to kill the aliens. This wouldn't be very creative, as it is only a slight twist on War of the Worlds, but it would have been a plausible ending.

Instead, Mr. Weber came up with a "brilliant" idea. Remember how one of the areas featured resisting the aliens was Romania? Weber brought them into the picture by having a soldier returning from Afghanistan have his C-130 plane crash in the area, leaving him and a few other Americans stranded in the area. They were found by a local group of backwoods Romanians, who led the American soldiers back to their camp. They fought a few times against the aliens alongside the U.S. soldiers. The Romanians were represented by Weber as being extremely stealthy guys able to sneak up and slit the throats of alien soldiers. The climax of this portion of the novel was that the aliens decided to send a large force to attack the Romanian camp, prompting a large fight that eventually killed most of the Americans.

This pissed the Romanians off quite a bit, so they revealed their true nature by turning into gas clouds and slaughtering all the aliens with their vampiric powers. They then flew up to the alien ships in orbit and killed all of them up there as well. Apparently their stealthy nature was supposed to foreshadow that the Romanian leader was Dracula and his companions were vampires hiding out for all these centuries in the Romanian backwoods.

Wait what?


I guess David Weber feels like he might have a good reason to keep that cross handy around his neck.

Why this is a Bad Ending
Besides the fact that vampires are massively overused in books right now as it is, there was absolutely no hint that this was going to happen anywhere before the end of the book. David Weber did a great job building up a somewhat plausible story where resistance forces acquired weapons and figured out how to fight an enemy capable of throwing meteors down on top of anyone putting up too much resistance. He then threw all of that away in the final couple of chapters by throwing in invulnerable vampires with godlike powers to easily slaughter every single one of the aliens and save humanity. As an author, if you're going to have some crazy shit like that happen at the end of your novel, you really need to foreshadow it, not spring it up out of nowhere because you only have a few pages left to end the book.

About the only positive thing I have to say about the vampires is that at least they didn't sparkle.