Shades of Grey……..

(Don’t worry, this isn’t about S&M…although please feel free to read on in your Gimp mask, if that’s your thing.)

An interesting weekend for cancer stories.

First, on Saturday we had a rather downbeat assessment of the effectiveness of chemotherapy drugs.   “Many modern cancer drugs are of very little benefit to patients, according to a group of leading European experts…,”

Then, this morning, we had the triumphant announcement of a major breakthrough in immunotherapy.  “Prof Roy Herbst, chief of medical oncology at Yale Cancer Centre in the US, said the treatment, which uses the body’s immune system to attack cancerous cells, as potentially replacing chemotherapy as the standard cancer treatment within five years.”:

Now, the first thing to say is that neither of these stories is 100% correct.  The efficacy of chemotherapy treatments is not as bad as the first makes out, and the promise of immunotherapy is not as spectacular as the second story implies.   You get this sort of story all the time.  The media, especially the newspapers, just love a nice, simple cancer story.  But the truth is a bit more complicated.  If you dig into the stories a bit more, you start to realise that things are not as black & white as they first appear.

First off, let’s look at  the assessment of chemotherapy.  The researchers took individual drugs or combined treatments and looked at the average effectiveness in different diseases.  They gave the overall efficacy a score of 1-5.  In their view, any drug or treatment which scored 3 or less was not an effective treatment.  Only those which scored 4 or 5 made the grade.  Now, what you have to realise first of all is that the researchers were not attempting to assess every drug in every disease.  They were trying to develop a tool to help in the critical assessment of clinical trial data.  So, for the media to report this as an investigation into the effectiveness of chemotherapy drugs in general, is misleading.  Also, the results of this study showed that the same drug, used to treat the same disease, can have different effects, depending on the circumstances.  If you’ve read my previous post, No cure for cancer….?, you’ll remember that I explained that, eg. Lung Cancer was not one single disease, but could be split into a variety of different diseases, each with their own sensitivities to treatment.  This same distinction is seen in the chemotherapy study.  So, for example, a Prostate Cancer treatment called Enzalutamide either has a score of 4 (ie. good), or a score of 3 (ie. not good), depending on the specific Prostate Cancer setting.  So the results are not black & white, but shades of grey.

Now, lets look at the triumphant immunotherapy story.  The treatment investigated used a combination of agents to kick-start an anti-cancer immune response by overcoming the MHC self-recognition system I talked about in No cure for cancer….?  This treatment showed efficacy in 58% of patients.  Now that is fantastic.  Seriously.  It’s a really encouraging result and shows that this treatment could be beneficial for a helluva lot of people.  But (you could tell it was coming, right?)  read that stat again.  Effective in 58%.  Therefore, this means it was not effective in 42% of patients.  So, again we see different effects in different patient cohorts.  Also, even in the 58% where the combined immunotherapy worked, the researchers added this caveat, “combining these treatments also increases the likelihood of potentially quite severe side effects.”  So, not quite the triumphant breakthrough proclaimed by Bill Turnbull on the breakfast news this morning.   Again, not black & white, but shades of grey.

So, whenever you see a cancer story in the paper, don’t take it at face value.  The world is more complex than is often reported.

AG McCluskey (2015). Shades of Grey…….. Zongo’s Cancer Diaries


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