The Cheerful Oncologist

Abraham Cherrix and the Fallacy of Moderation

Posted by Craig Hildreth on June 21, 2007
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Fellow ScienceBlogger Orac has posted the latest on Abraham Cherrix, the Virginia teenager who rejected conventional medical therapy for his relapsed Hodgkin lymphoma in favor of what we in the business call “spot-weld” radiation therapy, as well as unproven alternative supplements, presumably ingestibles. Since this story has piqued my interest I would like to comment on what appears to be a tragedy in the making.

Mr. Cherrix is back under the care of his radiation oncologist in Mississippi, getting XRT to a “small tumor on his right lung that showed up on a scan taken last week”. He gives the following explanation for his relapse:

“When you consider that I’ve had cancer four or five times, and each time it’s been an aggressive cancer with massive tumors or spreadout small tumors where there wasn’t much we could do for treatment, when you have no cancer in your lymph system and a small tumor somewhere else, it’s not really that big of a deal.”

His mother is quoted as saying: “The cancer’s not on the level that it was before, so what we are doing is working”; and “He’s got a spot in his lung, but hey, look at the big picture here.”

To me this line of reasoning is a good example of a logical fallacy called the Golden Mean Fallacy, or the Fallacy of Moderation.

This fallacy is committed when it is assumed that the middle position between two extremes must be correct simply because it is the middle position. This sort of “reasoning” has the following form:

Position A and B are two extreme positions.
C is a position that rests in the middle between A and B.
Therefore C is the correct position.

Using Mr. Cherrix’s reasoning, then, position A is “The cancer has not returned, therefore my treatments have worked” and position B is “The cancer has relapsed throughout my body, therefore my treatments have failed.” Position C, the middle ground position, would thus be “My cancer has only come back in one area, therefore my treatments have worked on most of my cancer.” Why do I consider this to be fallacious logic?

The answer is because patients with active relapsed Hodgkin lymphoma do not live long; unlike other chronic illnesses Hodgkin disease kills if it is not killed itself. There is no middle ground; no partial credit is given for eliminating some of the tumor.

Now it is documented that patients who relapse after initial chemotherapy can be cured with salvage radiation therapy, but such treatment is only given to highly selected patients:

Patients enrolled in these studies are a highly selected patient population. For instance, in the study from Josting et al., only 100 patients (approximately 2%) eventually underwent this treatment approach out of 4,754 patients enrolled in the German Hodgkin Lymphoma Study Group trials HD4 -HD9. These studies suggest that patients who have early-stage disease with no extranodal sites of involvement, lack of B symptoms, and a good response to first-line therapy are the best candidates for this approach.

So long-term survival has been achieved with just radiation therapy alone. Could Mr. Cherrix be one of these lucky patients?

Of course he could, and I pray that he is one. The problem is that according to the above-mentioned excerpt he has at least two unfavorable prognostic features. The first is his new relapse in the lung, an extranodal site:

On multivariate analysis significant factors for FFS [failure-free survival] were B symptoms at the time of SRT [salvage radiation therapy] (p = 0.003), extranodal involvement (p = 0.011) and histology (p = 0.018)…Our data suggest that patients most suitable for SRT are those with relapse in supradiaphragmatic nodal sites and no B symptoms.

The other discouraging sign is that his initial duration of remission, from his diagnosis in the late summer of 2005 to his relapse in February 2006 is less than one year:

Radical RT [radiation therapy] is an effective salvage regimen for select patients with advanced stage Hodgkin’s disease who relapse following initial treatment with chemotherapy alone provided that relapse is limited to sites which can be encompassed by radical RT fields and the DFI [disease-free interval] is greater than 12 months. Review of other published series supports DFI > 12 months as a favorable prognostic factor.

Even the results of chemotherapy (conventional or standard-dose, that is) after relapse from initial conventional chemotherapy are not great if the first complete remission was short:

If the time of relapse was within 1 year of obtaining a complete response, 49% achieved a second complete response. These remissions were not durable, and at 5 years, only 14% were disease-free. The median overall survival was 2.6 years for this group as a whole. This is in contrast to patients whose first complete remission lasted more than 12 months [my italics].

Thus, my final opinion: Abraham Cherrix should consider high-dose chemotherapy with stem cell support if he wants to cure his Hodgkin lymphoma. However, even this ultra-therapy has no guarantee of success, especially if one factors in his lung disease and his short duration of response to initial therapy:

Moskowitz et al. developed a prognostic model based on 65 consecutively treated patients with relapsed or refractory HD to predict the outcome from an autologous transplant. Three factors (i.e., extranodal sites of disease, complete response of less than 1-year duration or primary refractory disease, and B symptoms) predicted event-free survival. For patients with zero or one factor, the 5-year event-free and overall survivals were 83% and 90%, respectively. If two factors were present, the 5-year event-free and overall survivals were 27% and 57%, respectively, and this decreased to 10% and 25%, respectively, if all factors were present. In a study conducted by Stanford University, B symptoms, stage IV disease involving the bone marrow or lung, and greater-than-minimal residual disease at the time of presentation for transplantation were associated with a poor prognosis. The 3-year failure-from-progression was 85%, 57%, 41%, and <20% for zero, one, two, and three factors, respectively.

Sometimes it’s hard to be cheerful in this line of work. Abraham Cherrix is a good example of why.

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Comments

  1. #1 Ed Yong
    June 22, 2007

    Very interesting post Craig.

    The Fallacy of Moderation rears its ugly head all over the place, particularly in areas of public controversy or misconception. Take global warming – I’ve seen the following argument far too many times: Some people say that global warming isn’t real, some people say that it is real and it’s our fault, so the middle position must be right – it’s real but it’s only kind of our fault and we shouldn’t worry too much.

    I think the problem is especially pertinent in cases where the media seeks to ‘present both sides of the argument’ even when one side is overwhelmingly stronger. This causes a lot of people to automatically seek the halfway position.

  2. #2 Sean T
    June 22, 2007

    Yep, like Ed says, Republicans have been pulling this trick for ages. Take a reasonable Democratic position, and then put yourself into the extreme case of what you want. The public will then look to some sort of “middle ground” which is right of the Democratic positions, which is exactly what they want.

  3. #3 emmy
    June 22, 2007

    Can someone explain to me how a discussion on failed logic in medical situations becomes a political discussion? Just like a liberal to use that kind of failed thinking.

  4. #4 Richard Crawford
    June 22, 2007

    My doctor says my gangrenous foot must be removed; I say it should stay. Therefore, the best situation is to cut it halfway off. Right?

    The Fallacy of Moderation is pernicious just about everywhere as far as I can tell. But now I’m starting to get curious about what other logical fallacies show up in medical thinking; I imagine wishful thinking happens a lot as well.

  5. #5 marcia
    June 22, 2007

    medical failed logic and politics?

    Bush’s veto of stem cell research. He would like to use only those stem cell lines he feels are appropriate, a more “moderate position” between not using any and using those he chooses not to be used. Like I should value the faith-based scientist, Bush, over the scientist working 50 hrs a week for 20 years. Like I should value an embryo more than the health of a child. Like Bush’s middle-ground position = health benefit equivalent to that which can be achieved with embryos.

    What is most interesting is how Republicans care about the beginning of life (abortion, stem cells), the end of life (euthanasia) and Democrats care about everything in between.

  6. #6 HCN
    June 22, 2007

    emmy said “Can someone explain to me how a discussion on failed logic in medical situations becomes a political discussion? Just like a liberal to use that kind of failed thinking.”

    heh, heh, heh… have you not heard of Dan Burton, Orrin Hatch, or Tom Harkin? Meet the friends of the DSHEA… who completely handed over a market to a bunch of crooks:
    http://www.ergogenics.org/214.html

    They also want to muddle with pediatric vaccinations:
    http://www.huffingtonpost.com/arthur-allen/the-powerful-case-against_b_53233.html (Burton invited some folks from the UK who created a scare just to get more money).

    Note that they are both democrats and republicans… idiocy is not limited to one political party.

  7. #7 gpawelski
    June 24, 2007

    A failed attempt at chemotherapy is detrimental to the physical and emotional well being of patients, is financially burdensome, and may promote the onset of clinically acquired multi-drug resistance. Why not identify the right regimen before ever exposing a patient to a single course of chemotherapy?

    If patients treated with a “positive” (sensitive) drug would respond 79% of the time, while patients treated with a “negative” (resistant) drug would respond only 12% of the time, there would be a huge advantage to the patient to receive a “positive/sensitive” drug, compared to a “negative/resistant” drug.

    Cancer is a disease whose hallmark is hetrogeneity. It is well known that drugs which work for one patient often don’t work for another and patients who fail to respond to first line chemothrapy with one regimen often respond to second or third line therapy with alternative drugs.

    In light of the precious little in the way of guidance from clinical trials with respect to best empiric treatment, which is based on medical journal articles, epidemiology and economics, physician’s decisions need to be based on personal experience, clinical insights, and medical training.

  8. #8 Scott S.
    June 29, 2007

    If you believe that killing in the name of research is wrong, and I do, then killing embryos no matter what the ‘goodness’ of the goal is, is wrong.

    Besides embryonic stem cell therapies have a nasty side effect. Tumors. After all, cancer and embryos have rapid growth in common.

    Science will overtake politics and push back the limitations of the adult stem cell and make it as pluripotent as necessary.

    Liberal…’Of course the ends justify the means. It’s just a human life’

  9. #9 Tyler DiPietro
    July 3, 2007

    As with any discussion of ESCR, the cell-colony fetishists are coming out of the woodwork.

    “ZOMGBIES HUMAN LIFE!” Give me a break, what we’re working on are cultures of completely undifferentiated cells that would be discarded anyway in fertility clinics.

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