The Pⁿ Blog is a forum for opinions, questions, controversies, and instructive discussions across the field of pathology and its relevant subspecialties.
Friday, April 04, 2014
When the human genome project announced in 2000 that the 3 billion base pairs of human DNA had been successfully mapped, the thinking was that major breakthroughs in medicine were right in front of us. Surely the cures for Alzheimers, diabetes, all sorts of genetic conditions, and, of course, cancer were just around the corner. Well, as we now know, not quite. Clinical advances based on our knowledge of the human genome have been, at best, modest in the last 14 years. However, we may now be close to an inflection point in our utilization of this knowledge. The original government-funded Human Genome Project cost 3 billion dollars and took 13 years. It is now possible, with automated next generation sequencing to sequence an entire human genome for approximately $1000. At that price, individualized whole genome sequencing becomes a viable clinical tool.
Needless to say a LOT of venture capital is being thrown in this direction. Craig Venter, one of the pioneers in the Human Genome Project has started a company known as Human Longevity with the goal of completely sequencing 40,000 human genomes per year. This capability has considerable promise in a many medical fields. Fetal testing for genetic anomalies, for example, will be far more sensitive and allow the detection of a virtually endless number of anomalies, rather than a select few of the more common ones, as is now the case. Genetic components or predispositions will undoubted be found for many currently enigmatic diseases. Identification of these predispositions will allow for targeted screening and, in many instances, the development of specific therapies.
There will undoubtedly be major inroads in our understanding of cancer predispositions and targetted screenings in high risk populations. The benefits to this approach are likely to be enormous. Many cancers with specific mutations and a relatively stable genome may yield, at least initially, to targetted therapies. Drugs directed at tumors with specific mutations will have great potential as first line therapies with little or no associated toxicity. I remain skeptical, however, that targetted genetic therapy is going to result in dramatic long-term cure rates for many cancers, particularly those high-grade tumors with considerable genetic instability and the ability to "work around" initial genetic road blocks. GI stromal tumors (GISTs) are a case in point. These tumors have dramatic initial responses to Gleevec therapy and yet many (most) ultimately acquire the proper mutations for a biochemical "work around" of the Gleevec road block and Gleevec-resistant recurrences develop several years later. There may well be some biochemical road blocks for which work arounds aren't biologically possible, but cancer is, after all, "chaos" with entropy on its side and to paraphrase Jeff Goldblum in Jurassic Park, "life (even, or perhaps especially, malignant life) will find a way!"
The other looming issue on multiple levels is reimbursement! Will insurance companies pay for whole genome sequencing? Will they pay for enhanced screening based on detected predispositions? Will they pay for the development and utilization of costly drugs to treat rare and in some cases patient-specific diseases? At the moment reimbursement for molecular/genetic testing is in most cases a "loss leader" in medical centers. This has the potential to get much worse as the complexity and expense of the testing increases. Ultimately, market factors (read: patients demanding it), may lead to increased reimbursement in all these arenas, but only time will tell.
There's no doubt about it. We live in interesting times.
Friday, March 21, 2014
Is the Pap test dead? Well, no but there is about to be a radical change in how it is used. Last week an FDA advisory panel voted unanimously that the Pap smear should be replaced or at least supplemented by molecular tests for HPV DNA. The story was reported in a recent issue of the New York Times.
Up until now molecular testing was mainly done when the Pap smear was equivocal. The new recommendations reverse the order, however, and advise the use of a molecular test as the front line screen, with Pap smears or biopsies utilized in HPV+ patients. HPV testing has been widely reported to be more sensitive and more objective than a Pap smear. Opponents note that many young women become infected with HPV but clear the infection and have no residual morphologic sequelae. They fear that molecular testing may subject more women, particularly women under 30 years of age, to unnecessary examinations and biopsies. Roche, a maker of one molecular test, notes that they only test for high-risk HPV types 16 and 18.
The Pap smear is not dead; far from it. But its use as THE primary screening technique for cervical dysplasias and carcinomas is going to undergo considerable change in the next few years. The rapidity with which gynecologists switch from doing primary Pap smears to using HPV testing as their primary screen, or offering patients the choice will depend in large part on how soon their professional societies endorse the new FDA recommendations. Ultimately, though, high-volume Pap screening services looking at primarily low-risk patients are going to see a marked reduction in their volumes as molecular testing becomes the front line screen. Institutions such as my own that see a high percentage of high-risk patients will see less dramatic changes in Pap smear utilization.
The Pap smear has been and still is a fantastic tool for diagnosing pre-malignant cervical disease. In countries where it has been utilized routinely, it has resulted in a marked reduction in cervical cancer mortality. In the United States cervical cancer deaths decreased by 70% between 1955 and 1992. Recently, however, the mortality rate, though remaining low, has stabilized with no further reductions. Primary molecular screening, it is argued, is the next step in further lowering cervical cancer-related deaths. Dr. George Papanicolaou would, I think, approve.
Tuesday, February 25, 2014
In the past I have discussed the problems with overdiagnosis and overtreatment of both mammary carcinoma in situ and prostatic adenocarcinoma. A notable third example is the overdiagnosis and overtreatment of papillary thyroid carcinoma. A recent article from JAMA Otolaryngology - Head & Neck Surgery, entitled "Current Thryoid Cancer Trends in the United States
," and published online on February 20th details this problem.
To review some findings in the article:
Since 1975, the incidence of thyroid cancer has nearly tripled, from 4.9 to 14.3 per 100,000 individuals Virtually the entire increase is attributable to papillary thyroid cancer diagnoses. The absolute increase in thyroid cancer in women was almost 4 times greater than that of men. In spite of this dramatic increase, the mortality rate from thyroid cancer has remained stable between 1975 and 2009 (approximately 0.5 deaths per 100,000).
The authors conclude that there is an ongoing epidemic of thyroid cancer in the United States. The epidemiology of the increased incidence, however, suggests that it is not an epidemic of disease but rather an epidemic of diagnosis. The problem is particularly acute for women, who have lower autopsy prevalence of thyroid cancer than men but higher cancer detection rates by a 3:1 ratio.
That there is an epidemic of overdiagnosis and not of disease is based on the facts that: The increasingly detected cancers are highly unlikely to cause symptoms or death. Despite a more than 2-fold increase in the rate of thyroid cancer detection, thyroid cancer mortality had remained stable. Virtually all of the increase was confined to a type with the least aggressive histologic characteristics, namely papillary thyroid cancer. Finally, the bulk of the increase (87%) was explained by tumors 2 cm or smaller.
It is not surprising that women have bourne the brunt of this phenomenon. Benign thyroid disease is more common in women, leading to fine needle aspirations, and surgical resections that uncover occult and largely harmless lesions. Clinicians, the article suggests, are "looking too hard" for thyroid carcinomas. Because the article is a large review based on SEER data, there is no discussion regarding what culpability pathologists might bear for this "epidemic."
The article does not distinguish between conventional papillary carcinoma, a usually straightforward diagnosis, and the follicular variant, which, as any consultant reviewing such cases will attest, is often anything but straightforward. Indeed, the latter diagnosis is associated with considerable interobserver variability and given the overall excellent prognosis, refining diagnostic criteria would require a huge database with tens of thousands of years of patient follow up.
As mentioned above, a related issue that is discussed is the diagnosis of unequivocal but very small papillary carcinomas; lesions for which the term "microcarcinoma" has been used (and I also follow this practice). The authors raise the issue of whether such lesions should carry a designation other than "carcinoma," with all its associated connotations and emotional baggage. At the very least, clinicians should share with patients the extremely indolent behavior of small papillary carcinomas, and suggest the possibility of watchful waiting as appropriate therapy. After all, this is a tumor for which we have "magic bullet" therapy if needed. The current statistic of 85% total thyroidectomy following a diagnosis of papillary carcinoma (of any type or size) is far too high.
Monday, February 10, 2014
Pathologists and clinicians have been taught for decades that atypical lobular hyperplasia (ALH) and atypical ductal hyperplasia (ADH) of the breast are fundamentally different lesions. ALH has been viewed as a marker for subsequent carcinoma of lesser predictive power than lobular carcinoma in situ (LCIS), and associated with increased risk of carcinoma in either breast (although Page and colleagues did show that 2/3rds of subsequent carcinomas occur in the ipsilateral breast).
ADH has been viewed traditionally as a precursor lesion with more power than ALH to predict subsequent carcinoma, predominantly in the same breast. Surgeons will often do reexcisions when ADH is present at the margin but almost all will ignore margins positive for ALH (or even LCIS).
A recent article published in Cancer Prevention Research
based on a large study from the Mayo Clinic calls these assumptions into question. I recommend reading it and passing it on to your colleagues, both in pathology and the clinical specialties involved in breast disease management. There are a LOT more data in the text than are briefly discussed here.
The study involved almost 700 women with atypical hyperplasias, 330 with ADH, 327 with ALH, and 32 with both. This is by far the largest follow-up study in the literature on atypical hyperplasias of both types. To cut to the chase, the conclusion can be summarized in the following quote from the manuscript, "Our observations do not support present assumptions that ADH and ALH have substantively different behaviors. More DCIS may occur in women with ADH than ALH (25% vs. 13%, p=0.07), but numbers are small and this was not statistically significant."
Both ALH and ADH have features suggestive of precursor lesions and risk indicators. When carcinoma arises (either in-situ or invasive) both are predominantly associated with ductal as opposed to lobular carcinomas (ALH -> 77% ductal, 17% lobular; ADH -> 78% ductal, 8% lobular). Two-thirds of subsequent carcinomas arose in the ipsilateral breast in both ALH and ADH patients. Both ALH and ADH showed a tendency for contralateral carcinomas to develop later in life.
This is an valuable study that is packed with information, presented in a well-written format. Table 2 is especially data dense.
The authors conclude with the following:
"In summary, these findings underscore the importance of both ADH and ALH as premalignant lesions arising in an
altered tissue bed. The affected breast is at especially high risk for breast cancer in the first 5 years after diagnosis of breast cancer, with risk remaining elevated in both breasts long term. Both ADH and ALH portend risk for DCIS and invasive breast cancers, predominantly ductal, with two thirds moderate or high grade. These longitudinal data can help to inform clinical management strategies."
Although I think this is a very good study, I do have concerns that clinicians will interpret it to mean that ALH should treated more aggressively. I would argue that it rather suggests that ADH be treated more like ALH. The other problem(s), of course, are the distinctions between ALH & LCIS, and ADH & DCIS. A topic we've dealt with before.
Monday, January 27, 2014
In the past I have discoursed (ranted) in this blog space about pathologists' sins, primarily relating to the overuse of immunohistochemistry. The result of this practice has been across the board, "draconian" cuts in 83342 reimbursements, following on the heals of last year's cuts in 88305's. It could (and has) been argued that we brought this on ourselves.
However, we can take some perhaps perverse comfort in the fact that pathologists are real pikers when it comes to the occasional practice of procedure padding. I refer you to the following article in a recent issue of the New York Times
dealing with unnecessary procedures and charges in the world of dermatology.
The story focuses on a history professor at the University of Central Arkansas who saw a dermatologist for a small lesion on her cheek which turned out (I think) to be a very small basal cell carcinoma. By the time she had undergone resection with Mohs surgery and a plastic surgery closure the resultant bill topped $25,000! The charge for the plastic surgery closure alone (two stitches) was over $14,000! To say that the article takes a dim view of this approach and the physicians who follow such therapeutic overkill would be a major understatement.
As the article points out, procedures no matter how small are the big money makers in the medical world today. The easier they are and the faster you can perform them, the more likely you are to make large amounts of money. A good cardiac surgeon can perform, at most, two bypass surgeries a day but other specialists can do dozens of small procedures (biopsies, excisions, endoscopies, etc) in the same amount of time, often generating even more revenue than a busy heart surgeon.
Although the article deals in part with the rise and unnecessary use in many cases of Mohs surgery and the dramatic rise in dermatologist incomes in the last decade, they are not the only ones in the "cross hairs." The article notes, for example that oncologists make a substantial part of their income based on their ability to mark up chemotherapy charges. Urologists, the article mentions, often make 50% or more of their income from radiation administering equipment that they own, or from laboratories on their premises.
Those of us who are salaried academic physicians have been rather insulated from this phenomenon. It's undoubtedly true that patients in academic hospitals sometimes get more studies and procedures than they absolutely need due to a variety of causes including system inefficiencies, obsessive compulsive academic clinicians, trainees ordering unnecessary tests, intellectual curiosity, etc. At least phycician greed isn't a motive in the salaried physician model. Hospital administrators may be another story!
The vast majority of physicians of all types are dedicated, ethical, honest individuals who have devoted their life, often at considerable personal sacrifice, to help the sick. It's unfortunate that some really "bad apples" seem to be getting most (or all) of the press these days.