Friday, September 11, 2009
Glenn Reynolds links to the "new rules for skin cancer checks," an article in the New York Times that suggests that regular screenings for skin cancer do not improve outcomes.
Maybe, or maybe not. Read closely, grasshopper:
In updated guidelines issued last February and printed in The Annals of Internal Medicine, the task force found insufficient evidence to justify periodic “screening for skin cancer by primary care clinicians or by patient self-examination.” (emphasis added)
What about exams by dermatologists? Perhaps because I work for a company that caters to medical specialties -- neurosurgeons, and their ilk -- it has never occurred to me to go to my primary care physician for a dermatological exam. I have an appointment for a body exam from an actual dermatologist in about six weeks, and I intend to keep it.
My choice -- the decision to go to a specialist for a body exam -- is exactly the sort of "overutilization" that progressive cost-cutting "reformers" would hope to abolish, political rhetoric notwithstanding. Now, I'm not suggesting for a moment that I should not have to pay for my decision, but I would resent being deprived of the option because it is "not fair" that I can pay my own way or because Barack Obama decrees that we must reduce the cost of health care as a percentage of GDP.
Statistically speaking, screening for breast cancer also doesn't improve outcomes. The billions of dollars we spend on "free" mammograms? A great way to buy female voters, but they don't change 5-year life expectancy at all. That's because the real driver of life expectancy isn't detection, it's how aggressively the cancer grows.
That could not be farther from the truth! Screening mammography and newer digital mammography has downstaged the average tumor size at presentation and has been instrumental in improving long term survival. The overwhelming majority of my breat cancer patients no longer lose a breast to the disease...and more importantly...no longer lose their lives.
Certain things don't change...like the biology of the disease (doubling rate of the tumor), but early detection simplifies treatment and saves lives.
Check out the American Cancer Society website...or the medical literature.
....and if you are a woman over 40...get a mammogram!
Your statement represents, I think, the most prevalent medical opinion but a small subset of researchers thinks the issue is unsettled. Check out Michael Retsky's comments (BMC Med Inform Decis Mak. 2009; 9:20) on a paper by Keen and Keen in the same issue.
Retsky M, Demicheli R, Hrushesky W. Breast cancer screening for women aged 40–49 years: screening may not be the benign process usually thought. J Natl Cancer Inst. 2001;93:1572.
Retsky has a faculty appointment of some kind at Harvard Medical School and has co-authored some papers with the late Judah Folkman.
The most curable cancer is the false positive - screening generates plenty of those! According to the NCI, the death rate from breast cancer has not changed at all for white women since the 50-ies and it increases for blacks.
Screening mammography and newer digital mammography has downstaged the average tumor size at presentation... The overwhelming majority of my breast cancer patients no longer lose a breast to the disease
You're confusing treatment quality with mortality. As Joe notes, mortality numbers haven't changed despite the vast sums of money we spend on early detection. That is especially damning given the higher quality of treatment available today. A sound analysis would conclude that giving away mammograms is wasted money, therefore all such programs should cease. Not a political winner, is it?
Certain things don't change...like the biology of the disease (doubling rate of the tumor)
Exactly. Remember that no known cancer treatment eradicates 100% of cancer cells. An aggressive cancer that doubles every month puts you back where you started in 12-18 months. Because your body can't take chemo and radiation on a schedule like that, you're fighting a battle you can't win no matter when you detected the tumor.
On the other hand, a slow growing cancer takes on the order of 30 years to grow to a threatening (as opposed to a merely detectable) size . That breast cancer you detected at 65 probably started in her 30s, and once treated she'll almost certainly die of old age before the cancer is a problem again. If she makes it to 95, she's probably too frail to give her chemo and radiation. Besides, that's hardly being cheated out of a good long life.
Many medical researchers are not well trained in statistics. This is another example of proving the null hypothesis--assuming that not finding a significant difference means there is no difference.
The problem is there are a million reasons for no significant difference--many of which have nothing to do with the efficacy of treatment.
I learned my lesson this summer, when I ignored an ugly-looking mole on my shoulder, and went to the dermatologist just in time to get big surgery and a summer of no pool time. Go to the dermatologist, who may have mastered the magic of looking at a mole and discerning whether it is a melanoma or benign. I cant tell the difference, but most of them can.
"According to the NCI, the death rate from breast cancer has not changed at all for white women since the 50-ies and it increases for blacks"
Joe, I'd like to see where you got that factoid. It's wrong. Breast cancer deaths have dropped an average of 2.4% between 1990 and 2005 for caucasian women because of better detection/earlier diagnosis. The rates are higher in other groups (African-Americans, for instance)for reasons that may be socioeconomic or cultural...but obviously deserve further analysis.
Screening generates "false positives" ????
I'm not sure what you mean by that. Every abnormality of significance on a screening study should undergo a simple biopsy (usually done without surgery and under local anesthesia) and microscopic pathologic confirmation.
Sure, the screening does generate some biopsies that are negative for tumor...unless it's YOUR biosy that's positive...then the screening saves YOUR LIFE.
How can one be opposed to this??? Trying to save a few bucks?
In any event...this is a public forum, so please check your facts. Anyone who cancels their screening mammogram on the basis of that information is clearly not well served.
The data on this site ends in 1994. You can see the curve beginning to dip down in the last measured quartile, as noted in my post above.
In addition, it has been demonstrated that countries with effective screening programs have a HIGHER incidence of breast cancer...of course reflecting the improved detection of cases.
Since five year survival statistics cover all stages of the disease at diagnosis...there is an expected LAG in the onset of improved 5 year survival after the initiation of an effective screening program.
The data tracking into the current decade clearly reveals this...again as noted in my post above.